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• C#: Searching through arrays

  - by Jonathan Oberhaus

  I have a dvd app that stores dvds and blu-rays, I want to search the arrays by director. Below is the code for the inventory class I have seen many different ways to do this. There seems to be some debate as the best/most efficient way to accomplish this, any suggestions? Blockquote namespace MovieInventoryApplication { class Inventory { public Bluray[] BlurayMovies; public DVD[] DVDMovies; private int blurayCount; private int dvdCount; public Inventory() { BlurayMovies = new Bluray[5]; DVDMovies = new DVD[5]; blurayCount = 0; dvdCount = 0; } public void AddBluray() { String strTitle; int intReleaseYear; int intRunningTimeMinutes; String strDirector; int intPrice; int intRegionCode; try { Console.Write("Enter a title: "); strTitle = Console.ReadLine(); Console.Write("Enter a release year: "); intReleaseYear = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter the running time in minutes: "); intRunningTimeMinutes = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter the directors name: "); strDirector = Console.ReadLine(); Console.Write("Enter a rental price: "); intPrice = Convert.ToInt32(Console.ReadLine()); BlurayMovies[blurayCount] = new Bluray(strTitle, intReleaseYear, intRunningTimeMinutes, strDirector, intPrice); blurayCount++; Console.Write("Enter the DVD region code: "); intRegionCode = Convert.ToInt32(Console.ReadLine()); DVDMovies[dvdCount] = new DVD(strTitle, intReleaseYear, intRunningTimeMinutes, strDirector, intPrice, intRegionCode); dvdCount++; } catch (FormatException FormatException) { Console.WriteLine(FormatException.Message); Console.WriteLine("Please enter a number in this field."); } } public void AddDVD() { String strTitle; int intReleaseYear; int intRunningTimeMinutes; String strDirector; int intPrice; int intRegionCode; try { Console.Write("Enter a title: "); strTitle = Console.ReadLine(); Console.Write("Enter a release year: "); intReleaseYear = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter the running time in minutes: "); intRunningTimeMinutes = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter the directors name: "); strDirector = Console.ReadLine(); Console.Write("Enter a rental price: "); intPrice = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter the region code: "); intRegionCode = Convert.ToInt32(Console.ReadLine()); DVDMovies[dvdCount] = new DVD(strTitle, intReleaseYear, intRunningTimeMinutes, strDirector, intPrice, intRegionCode); dvdCount++; } catch (FormatException FormatException) { Console.WriteLine(FormatException.Message); Console.WriteLine("Please enter a number in this field."); } } public void ListAllBluray() { int position = 0; while (BlurayMovies[position] != null) { Console.WriteLine(position + " " + BlurayMovies[position].strTitle); position++; } } public void ListAllDVD() { int position = 0; while (DVDMovies[position] != null) { //position + 1 + " " + Console.WriteLine(position + " " + DVDMovies[position].strTitle); position++; } } public void BlurayInfo(int position) { Console.WriteLine("Title: {0}", DVDMovies[position].strTitle); Console.WriteLine("Release Year: {0}", DVDMovies[position].intReleaseYear); Console.WriteLine("Running Time (Minutes): {0}", DVDMovies[position].intRunningTimeMinutes); Console.WriteLine("Director: {0}", DVDMovies[position].strDirector); Console.WriteLine("Price: {0}", DVDMovies[position].intPrice); } public void DVDInfo(int position) { Console.WriteLine("Title: {0}", DVDMovies[position].strTitle); Console.WriteLine("Release Year: {0}", DVDMovies[position].intReleaseYear); Console.WriteLine("Running Time (Minutes): {0}", DVDMovies[position].intRunningTimeMinutes); Console.WriteLine("Director: {0}", DVDMovies[position].strDirector); Console.WriteLine("Price: {0}", DVDMovies[position].intPrice); Console.WriteLine("Region Code: {0}", DVDMovies[position].intRegionCode); } } }

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• E-Business Suite Technology Sessions at OpenWorld 2012

  - by Max Arderius

  Oracle OpenWorld 2012 is almost here! We're looking forward to updating you on our products, strategy, and roadmaps. This year, the E-Business Suite Applications Technology Group (ATG) will participate in 25 speaker sessions, two Meet the Experts round-table discussions, five demoground booths and seven Special Interest Group meetings as guest speakers. We hope to see you at our sessions.  Please join us to hear the latest news and connect with senior ATG development staff. Here's a downloadable listing of all Applications Technology Group-related sessions with times and locations: FOCUS ON Oracle E-Business Suite - Applications Tools and Technology (PDF) General Sessions GEN8474 - Oracle E-Business Suite - Strategy, Update, and RoadmapCliff Godwin, SVP, Oracle Monday, Oct 1, 12:15 PM - 1:15 PM - Moscone West 2002/2004 In this session, hear Oracle E-Business Suite General Manager Cliff Godwin deliver an update on the Oracle E-Business Suite product line. This session covers the value delivered by the current release of Oracle E-Business Suite, the momentum, and how Oracle E-Business Suite applications integrate into Oracle’s overall applications strategy. You’ll come away with an understanding of the value Oracle E-Business Suite applications deliver now and will deliver in the future. GEN9173 - Optimize and Extend Oracle Applications - The Path to Oracle Fusion ApplicationsNadia Bendjedou, Oracle; Corre Curtice, Bhavish Madurai (CSC) Tuesday, Oct 2, 10:15 AM - 11:15 AM - Moscone West 3002/3004 One of the main objectives of this session is to help organizations build their IT roadmap for the next five years and be aligned with the Oracle Applications strategy in general and the Oracle Fusion Applications strategy in particular. Come hear about some of the common sense, practical steps you can take to optimize the performance of your Oracle Applications today and prepare your path to Oracle Fusion Applications for when your organization is ready to embrace them. Each step you take in adopting Oracle Fusion technology gets you partway to Oracle Fusion Applications. Conference Sessions CON9024 - Oracle E-Business Suite Technology: Latest Features and Roadmap Lisa Parekh, Oracle Monday, Oct 1, 10:45 AM - 11:45 AM - Moscone West 2016 This Oracle development session provides a comprehensive overview of Oracle’s product strategy for Oracle E-Business Suite technology, the capabilities and associated business benefits of recent releases, and a review of capabilities on the product roadmap. This is the cornerstone session for the Oracle E-Business Suite technology stack. Come hear about the latest new usability enhancements of the user interface; systems administration and configuration management tools; security-related updates; and tools and options for extending, customizing, and integrating Oracle E-Business Suite with other applications. CON9021 - Oracle E-Business Suite Future Directions: Deployment and System AdministrationMax Arderius, Oracle Monday, Oct 1, 3:15 PM - 4:15 PM - Moscone West 2016  What’s coming in the next major version of Oracle E-Business Suite 12? This Oracle Development session covers the latest technology stack, including the use of Oracle WebLogic Server (Oracle Fusion Middleware 11g) and Oracle Database 11g Release 2 (11.2). Topics include an architectural overview of the latest updates, installation and upgrade options, new configuration options, and new tools for hot cloning and automated “lights-out” cloning. Come learn how online patching (based on the Oracle Database 11g Release 2 Edition-Based Redefinition feature) will reduce your database patching downtimes to however long it takes to bounce your database server. CON9017 - Desktop Integration in Oracle E-Business Suite 12.1 Padmaprabodh Ambale, Gustavo Jimenez, Oracle Monday, Oct 1, 4:45 PM - 5:45 PM - Moscone West 2016 This presentation covers the latest functional enhancements in Oracle Web Applications Desktop Integrator and Oracle Report Manager, enhanced Microsoft Office support, and greater support for building custom desktop integration solutions. The session also presents tips and tricks for upgrading from Oracle Applications Desktop Integrator to Oracle Web Applications Desktop Integrator and Oracle Report Manager. CON9023 - Oracle E-Business Suite Technology Certification Primer and Roadmap Steven Chan, Oracle Tuesday, Oct 2, 10:15 AM - 11:15 AM - Moscone West 2016  Is your Oracle E-Business Suite technology stack up to date? Are you taking advantage of all the latest options and capabilities? This Oracle development session summarizes the latest certifications and roadmap for the Oracle E-Business Suite technology stack, including elements such as database releases and options, Java, Oracle Forms, Oracle Containers for J2EE, desktop operating systems, browsers, JRE releases, development and Web authoring tools, user authentication and management, business intelligence, Oracle Application Management Packs, security options, clouds, Oracle VM, and virtualization. The session also covers the most commonly asked questions about tech stack component support dates and upgrade implications. CON9028 - Minimizing Oracle E-Business Suite Maintenance DowntimesSantiago Bastidas, Elke Phelps, Oracle Tuesday, Oct 2, 11:45 AM - 12:45 PM - Moscone West 2016 This Oracle development session features a survey of the best techniques sysadmins can use to minimize patching downtimes. It starts with an architectural-level review of Oracle E-Business Suite fundamentals and then moves to a practical view of the various tools and approaches for downtimes. Topics include patching shortcuts, merging patches, distributing worker processes across multiple servers, running ADPatch in noninteractive mode, staged APPL_TOPs, shared file systems, deferring systemwide database tasks, avoiding resource bottlenecks, and more. An added bonus: hear about the upcoming Oracle E-Business Suite 12 online patching capabilities based on the groundbreaking Oracle Database 11g Release 2 Edition-Based Redefinition feature. CON9116 - Extending the Use of Oracle E-Business Suite with the Oracle Endeca PlatformOsama Elkady, Muhannad Obeidat, Oracle Tuesday, Oct 2, 11:45 AM - 12:45 PM - Moscone West 2018 The Oracle Endeca platform includes a leading unstructured data correlation and analytics engine, together with a best-in class catalog search and guided navigation solution, to improve the productivity of all types of users in your enterprise. This development session focuses on the details behind the Oracle Endeca platform’s integration into Oracle E-Business Suite. It demonstrates how easily you can extend the use of the Oracle Endeca platform into other areas of Oracle E-Business Suite and how you can bring in your own data and build new Oracle Endeca applications for Oracle E-Business Suite. CON9005 - Oracle E-Business Suite Integration Best PracticesVeshaal Singh, Oracle, Jeffrey Hand, Zebra Technologies Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2018 Oracle is investing across applications and technologies to make the application integration experience easier for customers. Today Oracle has certified Oracle E-Business Suite on Oracle Fusion Middleware 11g and provides a comprehensive set of integration technologies. Learn about Oracle’s integration offering across data- and process-centric integrations. These technologies can be used to address various application integration challenges and styles. In this session, you will get an understanding of how, when, and where you can leverage Oracle’s integration technologies to connect end-to-end business processes across your enterprise, including your Oracle Applications portfolio.  CON9026 - Latest Oracle E-Business Suite 12.1 User Interface and Usability EnhancementsPadmaprabodh Ambale, Oracle Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2016 This Oracle development session details the latest UI enhancements to Oracle Application Framework in Oracle E-Business Suite 12.1. Developers will get a detailed look at new features to enhance usability, offer more capabilities for personalization and extensions, and support the development and use of dashboards and Web services. Topics include new rich UI capabilities such as new home page features, Navigator and Favorites pull-down menus, REST interface, embedded widgets for analytics content, Oracle Application Development Framework (Oracle ADF) task flows, third-party widgets, a look-ahead list of values, inline attachments, pop-ups, personalization and extensibility enhancements, business layer extensions, Oracle ADF integration, and mobile devices. CON8805 - Planning Your Oracle E-Business Suite Upgrade from 11i to Release 12.1 and BeyondAnne Carlson, Oracle Tuesday, Oct 2, 5:00 PM - 6:00 PM - Moscone West 3002/3004 Attend this session to hear the latest Oracle E-Business Suite 12.1 upgrade planning tips from Oracle’s support, consulting, development, and IT organizations. You’ll get specific cross-product advice on how to understand the factors that affect your project’s duration, decide on your project’s scope, develop a robust testing strategy, leverage Oracle Support resources, and more. In a nutshell, this session tells you things you need to know before embarking upon your Release 12.1 upgrade project. CON9053 - Advanced Management of Oracle E-Business Suite with Oracle Enterprise ManagerAngelo Rosado, Oracle Tuesday, Oct 2, 5:00 PM - 6:00 PM - Moscone West 2016 The task of managing and monitoring Oracle E-Business Suite environments can be very challenging. Oracle Enterprise Manager is the only product on the market that is designed to monitor and manage all the different technologies that constitute Oracle E-Business Suite applications, including end user, midtier, configuration, host, and database management—to name just a few. Customers that have implemented Oracle Enterprise Manager have experienced dramatic improvements in system visibility and diagnostic capability as well as administrator productivity. The purpose of this session is to highlight the key features and benefits of Oracle Enterprise Manager and Oracle Application Management Suite for Oracle E-Business Suite. CON8809 - Oracle E-Business Suite 12.1 Upgrade Best Practices: Technical InsightIsam Alyousfi, Udayan Parvate, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 3011 This session is ideal for organizations thinking about upgrading to Oracle E-Business Suite 12.1. It covers the fundamentals of upgrading to Release 12.1, including the technology stack components and supported upgrade paths. Hear from Oracle Development about the set of best practices for patching in general and executing the Release 12.1 technical upgrade, with special considerations for minimizing your downtime. Also get to know about relatively recent upgrade resources. CON9032 - Upgrading Your Customizations of Oracle E-Business Suite 12.1Sara Woodhull, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 2016 Have you personalized Oracle Forms or Oracle Application Framework screens in Oracle E-Business Suite? Have you used mod_plsql in Release 11i? Have you extended or customized your Release 11i environment with other tools? The technical options for upgrading these customizations as part of your Oracle E-Business Suite Release 12.1 upgrade can be bewildering. Come to this Oracle development session to learn about selecting the best upgrade approach for your existing customizations. The session will help you understand customization scenarios and use cases, tools, and technologies to ensure that your Oracle E-Business Suite Release 12.1 environment fits your users’ needs closely and that any future customizations will be easy to upgrade. CON9259 - Oracle E-Business Suite Internationalization and Multilingual FeaturesMaher Al-Nubani, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 2018 Oracle E-Business Suite supports more countries, languages, and regions than ever. Come to this Oracle development session to get an overview of internationalization features and capabilities and see new Release 12 features such as calendar support for Hijra and Thai, new group separators, lightweight multilingual support (MLS) setup, new character sets such as AL32UTF, newly supported languages, Mac certifications, Oracle iSetup support for moving MLS setups, new file export options for Unicode, new MLS number spelling options, and more. CON7188 - Mobile Apps for Oracle E-Business Suite with Oracle ADF Mobile and Oracle SOA SuiteSrikant Subramaniam, Joe Huang, Veshaal Singh, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 3001 Follow your mobile customers, employees, and partners with Oracle Fusion Middleware. See how native iPhone and iPad applications can easily be built for Oracle E-Business Suite with the new Oracle ADF Mobile and Oracle SOA Suite. Using Oracle ADF Mobile, developers can quickly develop native applications for Apple iOS and other mobile platforms. The Oracle SOA Suite/Oracle ADF Mobile combination can execute business transactions on Oracle E-Business Suite. This session includes a demo in which a mobile user approves a business transaction in Oracle E-Business Suite and a demo of the tools used to build a native on-device solution. These concepts for mobile applications also apply to other Oracle applications.CON9029 - Oracle E-Business Suite Directions: Slashing Downtimes with Online PatchingKevin Hudson, Oracle Wednesday, Oct 3, 11:45 AM - 12:45 PM - Moscone West 2016 Oracle E-Business Suite will soon include online patching (based on the Oracle Database 11g Release 2 Edition-Based Redefinition feature), which will reduce your database patching downtimes to however long it takes to bounce your database server. This Oracle development session details how online patching works, with special attention to what’s happening at a database object level when database patches are applied to an Oracle E-Business Suite environment that’s still running. Come learn about the operational and system management implications for minimizing maintenance downtimes when applying database patches with this new technology and the related impact on customizations you might have built on top of Oracle E-Business Suite. CON8806 - Upgrading to Oracle E-Business Suite 12.1: Technical and Functional PanelAndrew Katz, Komori America Corporation; Sandra Vucinic, VLAD Group, Inc. ;Srini Chavali, Cummins Inc.; Amrita Mehrok, Nadia Bendjedou, Anne Carlson Oracle Wednesday, Oct 3, 1:15 PM - 2:15 PM - Moscone West 2018 In this panel discussion, Oracle experts, customers, and partners share their experiences in upgrading to the latest release of Oracle E-Business Suite, Release 12.1. The panelists cover aspects of a typical Release 12 upgrade, technical (upgrading the technical infrastructure) as well as functional (upgrading to the new financial infrastructure). Hear directly from the experts who either develop the product or support, implement, or upgrade it, and find out how to apply their lessons learned to your organization. CON9027 - Personalize and Extend Oracle E-Business Suite Applications with Rich MashupsGustavo Jimenez, Padmaprabodh Ambale, Oracle Wednesday, Oct 3, 1:15 PM - 2:15 PM - Moscone West 2016 This session covers the use of several Oracle Fusion Middleware technologies to personalize and extend your existing Oracle E-Business Suite applications. The Oracle Fusion Middleware technologies covered include Oracle Application Development Framework (Oracle ADF), Oracle WebCenter, Oracle Endeca applications, and Oracle Business Intelligence Enterprise Edition with Oracle E-Business Suite Oracle Application Framework applications. CON9036 - Advanced Oracle E-Business Suite Architectures: Maximum Availability, Security, and MoreElke Phelps, Oracle Wednesday, Oct 3, 3:30 PM - 4:30 PM - Moscone West 2016 This session includes architecture diagrams and configuration instructions for building a maximum availability architecture (MAA) that will help you design a disaster recovery solution that fits the needs of your business. Database and application high-availability features it describes include Oracle Data Guard, Oracle Real Application Clusters (Oracle RAC), Oracle Active Data Guard, load-balancing Web and forms services, parallel concurrent processing, and the use of Oracle Exalogic and Oracle Exadata to provide a highly available environment. The session also covers the latest updates to systems management tools, AutoConfig, cloud computing, virtualization, and Oracle WebLogic Server and provides sneak previews of upcoming functionality. CON9047 - Efficiently Scaling Oracle E-Business Suite on Oracle Exadata and Oracle ExalogicIsam Alyousfi, Nishit Rao, Oracle Wednesday, Oct 3, 5:00 PM - 6:00 PM - Moscone West 2016 Oracle Exadata and Oracle Exalogic are designed from the ground up with optimizations in software and hardware to deliver superfast performance for mission-critical applications such as Oracle E-Business Suite. Oracle E-Business Suite applications run three to eight times as fast on the Oracle Exadata/Oracle Exalogic platform in standard benchmark tests. Besides performance, customers benefit from simplified support, enhanced manageability, and the ability to consolidate multiple Oracle E-Business Suite instances. Attend this session to understand best practices for Oracle E-Business Suite deployment on Oracle Exalogic and Oracle Exadata through customer case studies. Learn how adopting the Exa* platform increases efficiency, simplifies scaling, and boosts performance for peak loads. CON8716 - Web Services and SOA Integration Options for Oracle E-Business SuiteRekha Ayothi, Veshaal Singh, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 2016 This Oracle development session provides a deep dive into a subset of the Web services and SOA-related integration options available to Oracle E-Business Suite systems integrators. It offers a technical look at Oracle E-Business Suite Integrated SOA Gateway, Oracle SOA Suite, Oracle Application Adapters for Data Integration for Oracle E-Business Suite, and other Web services options for integrating Oracle E-Business Suite with other applications. Systems integrators and developers will get an overview of the latest integration capabilities and technologies available out of the box with Oracle E-Business Suite and possibly a sneak preview of upcoming functionality and features. CON9030 - Recommendations for Oracle E-Business Suite Performance TuningIsam Alyousfi, Samer Barakat, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 2018 Need to squeeze more performance out of your existing servers? This packed Oracle development session summarizes practical tips and lessons learned from performance-tuning and benchmarking the world’s largest Oracle E-Business Suite environments. Apps sysadmins will learn concrete tips and techniques for identifying and resolving performance bottlenecks on all layers, with special attention to application- and database-tier servers. Learn about tuning Oracle Forms, Oracle Concurrent Manager, Apache, and Oracle Discoverer. Track down memory leaks and other issues at the Java and JVM layers. The session also covers Oracle E-Business Suite product-level tuning, including Oracle Workflow, Oracle Order Management, Oracle Payroll, and other modules. CON3429 - Using Oracle ADF with Oracle E-Business Suite: The Full Integration ViewSiva Puthurkattil, Lake County; Juan Camilo Ruiz, Sara Woodhull, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 3003 Oracle E-Business Suite delivers functionality for handling the core business of your organization. However, user requirements and new technologies are driving an emerging need to implement new types of user interfaces for these applications. This session provides an overview of how to use Oracle Application Development Framework (Oracle ADF) to deliver cutting-edge Web 2.0 and mobile rich user interfaces that front existing Oracle E-Business Suite processes, and it also explores all the existing types of integration between the two worlds. CON9020 - Integrating Oracle E-Business Suite with Oracle Identity Management SolutionsSunil Ghosh, Elke Phelps, Oracle Thursday, Oct 4, 12:45 PM - 1:45 PM - Moscone West 2016 Need to integrate Oracle E-Business Suite with Microsoft Windows Kerberos, Active Directory, CA Netegrity SiteMinder, or other third-party authentication systems? Want to understand your options when Oracle Premier Support for Oracle Single Sign-On ends in December 2011? This Oracle Development session covers the latest certified integrations with Oracle Access Manager 11g and Oracle Internet Directory 11g, which can be used individually or as bridges for integrating with third-party authentication solutions. The session presents an architectural overview of how Oracle Access Manager, its WebGate and AccessGate components, and Oracle Internet Directory work together, with implications for Oracle Discoverer, Oracle Portal, and other Oracle Fusion identity management products. CON9019 - Troubleshooting, Diagnosing, and Optimizing Oracle E-Business Suite TechnologyGustavo Jimenez, Oracle Thursday, Oct 4, 2:15 PM - 3:15 PM - Moscone West 2016 This session covers how you can proactively diagnose Oracle E-Business Suite applications, including extensions built with Oracle Fusion Middleware technologies such as Oracle Application Development Framework (Oracle ADF) and Oracle WebCenter to catch potential issues in the middle tier before they become more serious. Topics include debugging, logging infrastructure, warning signs, performance tuning, information required when logging service requests, general JVM optimization, and an overall picture of all the moving parts that make it possible for Oracle E-Business Suite to isolate and fix problems. Also learn how Oracle Diagnostics Framework will help prevent downtime caused by failures. CON9031 - The Top 10 Things You Can Do to Secure Your Oracle E-Business Suite InstanceEric Bing, Erik Graversen, Oracle Thursday, Oct 4, 2:15 PM - 3:15 PM - Moscone West 2018 Learn the top 10 things you can do to secure your applications and your sensitive data. This Oracle development session for system administrators and security professionals explores some of the most important and overlooked things you can do to secure your Oracle E-Business Suite instance. It also covers data masking and other mechanisms for protecting sensitive data. Special Interest Groups (SIG) Some of our most senior staff have been invited to participate on the following SIG meetings as guest speakers: SIG10525 - OAUG - Archive & Purge SIGBrian Bent - Pre-Sales Engineer, TierData, Inc. Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3011 The Archive and Purge SIG is an organization in which users can share their experiences and solicit functional and technical advice on archiving and purging data in Oracle E-Business Suite. This session provides an opportunity for users to network and share best practices, tips, and tricks. Guest: Oracle E-Business Suite Database Performance, Archive & Purging - Q&A SessionIsam Alyousfi, Senior Director, Applications Performance, Oracle SIG10547 - OAUG - Oracle E-Business (EBS) Applications Technology SIGSrini Chavali - IT Director, Cummins Inc Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3018 The general purpose of the EBS Applications Technology SIG is to inform and educate its members about current and future components of the tech stack as they relate to Oracle E-Business Suite. Attend this meeting for networking and education and to share best practices. Guest: Oracle E-Business Suite Technology Certification Roadmap - Presentation and Q&ASteven Chan, Sr. Director, Applications Technology Group, Oracle SIG10559 - OAUG - User Management SIGSusan Behn - VP of Oracle Delivery, Infosemantics, Inc. Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3024 The E-Business Suite User Management SIG focuses on the components of user management that enable Oracle E-Business Suite users to define administrative functions and manage users’ access to functions and data based on roles within an organization—rather than the user’s individual identity—which is referred to as role-based access control (RBAC). This meeting includes an introduction to Oracle User Management that covers the Oracle User Management building blocks and presents an example of creating a security policy.Guest: Security and User Management - Q&A SessionEric Bing, Sr. Director, EBS Security, OracleSara Woodhull, Principal Product Manager, Applications Technology Group, Oracle SIG10515 - OAUG – Upgrade SIGBarbara Matthews - Consultant, On Call DBASandra Vucinic, VLAD Group, Inc. Sunday, Sep 30, 12:00 PM - 2:00 PM - Moscone West 3009 This Upgrade SIG session starts with a business meeting and then features a Q&A panel discussion on Oracle E-Business Suite upgrade topics. The session• Reviews Upgrade SIG goals and objectives• Provides answers, during the Q&A session, to questions related to Oracle E-Business Suite upgrades• Shares “real world” experiences, tips, and techniques for Oracle E-Business Suite upgrades to Release 12.1. Guest: Oracle E-Business Suite Upgrade - Q&A SessionAnne Carlson - Sr. Director, Oracle E-Business Suite Product Strategy, OracleUdayan Parvate - Director, EBS Release Engineering, OracleSuzana Ferrari, Sr. Principal Consultant, OracleIsam Alyousfi, Sr. Director, Applications Performance, Oracle SIG10552 - OAUG - Oracle E-Business Suite SIGDonna Rosentrater - Manager, Global Sourcing & Procurement Systems, TJX Sunday, Sep 30, 12:15 PM - 1:45 PM - Moscone West 3020 The E-Business Suite SIG, affiliated with OAUG, supports Oracle E-Business Suite users through networking, education, and sharing of best practices. This SIG meeting will feature a general discussion of Oracle E-Business Suite product strategies in Release 12 and migration to Oracle Fusion Applications. Guest: Oracle E-Business Suite - Q&A SessionJeanne Lowell, Vice President, EBS Product Strategy, OracleNadia Bendjedou, Sr. Director, Product Strategy, Oracle SIG10556 - OAUG - SysAdmin SIGRandy Giefer - Sr Systems and Security Architect, Solution Beacon, LLC Sunday, Sep 30, 12:15 PM - 1:45 PM - Moscone West 3022 The SysAdmin SIG provides a forum in which OAUG members and participants can share updates, tips, and successful practices relating to system administration in an Oracle applications environment. The SysAdmin SIG strives to enable system administrators to become more effective and efficient in their jobs by providing them with access to people and information that can increase their system administration knowledge and experience. Attend this meeting to network, share best practices, and benefit from educational content. Guest: Oracle E-Business Suite 12.2 Online Patching- Presentation and Q&AKevin Hudson, Sr. Director, Applications Technology Group, Oracle SIG10553 - OAUG - Database SIGMichael Brown - Senior DBA, COLIBRI LTD LC Sunday, Sep 30, 2:00 PM - 3:15 PM - Moscone West 3020 The OAUG Database SIG provides an opportunity for applications database administrators to learn from and share their experiences with supporting the various Oracle applications environments. This session will include a brief business meeting followed by a short presentation. It will end with an open discussion among the attendees about items of interest to those present. Guest: Oracle E-Business Suite Database Performance - Presentation and Q&AIsam Alyousfi, Sr. Director, Applications Performance, Oracle Meet the Experts We're planning two round-table discussions where you can review your questions with senior E-Business Suite ATG staff: MTE9648 - Meet the Experts for Oracle E-Business Suite: Planning Your Upgrade Jeanne Lowell - VP, EBS Product Strategy, Oracle John Abraham - Sr. Principal Product Manager, Oracle Nadia Bendjedou - Sr. Director - Product Strategy, Oracle Anne Carlson - Sr. Director, Applications Technology Group, Oracle Udayan Parvate - Director, EBS Release Engineering, Oracle Isam Alyousfi, Sr. Director, Applications Performance, Oracle Monday, Oct 1, 3:15 PM - 4:15 PM - Moscone West 2001A Don’t miss this Oracle Applications Meet the Experts session with experts who specialize in Oracle E-Business Suite upgrade best practices. This is the place where attendees can have informal and semistructured but open one-on-one discussions with Strategy and Development regarding Oracle Applications strategy and your specific business and IT strategy. The experts will be available to discuss the value of the latest releases and share insights into the best path for your enterprise, so come ready with your questions. Space is limited, so make sure you register. MTE9649 - Meet the Oracle E-Business Suite Tools and Technology Experts Lisa Parekh - Vice President, Technology Integration, Oracle Steven Chan - Sr. Director, Oracle Elke Phelps - Sr. Principal Product Manager, Applications Technology Group, Oracle Max Arderius - Manager, Applications Technology Group, Oracle Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2001A Don’t miss this Oracle Applications Meet the Experts session with experts who specialize in Oracle E-Business Suite technology. This is the place where attendees can have informal and semistructured but open one-on-one discussions with Strategy and Development regarding Oracle Applications strategy and your specific business and IT strategy. The experts will be available to discuss the value of the latest releases and share insights into the best path for your enterprise, so come ready with your questions. Space is limited, so make sure you register. Demos We have five booths in the exhibition demogrounds this year, where you can try ATG technologies firsthand and get your questions answered. Please stop by and meet our staff at the following locations: Advanced Architecture and Technology Stack for Oracle E-Business Suite (W-067) New User Productivity Capabilities in Oracle E-Business Suite (W-065) End-to-End Management of Oracle E-Business Suite (W-063) Oracle E-Business Suite 12.1 Technical Upgrade Best Practices (W-066) SOA-Based Integration for Oracle E-Business Suite (W-064)

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• Tools and Utilities for the .NET Developer

  - by mbcrump

  Tweet this list! Add a link to my site to your bookmarks to quickly find this page again! Add me to twitter! This is a list of the tools/utilities that I use to do my job/hobby. I wanted this page to load fast and contain information that only you care about. If I have missed a tool that you like, feel free to contact me and I will add it to the list. Also, this list took a lot of time to complete. Please do not steal my work, if you like the page then please link back to my site. I will keep the links/information updated as new tools/utilities are created.  Windows/.NET Development – This is a list of tools that any Windows/.NET developer should have in his bag. I have used at some point in my career everything listed on this page and below is the tools worth keeping. Name Description License AnkhSVN Subversion support for Visual Studio. It also works with VS2010. Free Aurora XAML Designer One of the best XAML creation tools available. Has a ton of built in templates that you can copy/paste into VS2010. COST/Trial BeyondCompare Beyond Compare 3 is the ideal tool for comparing files and folders on your Windows or Linux system. Visualize changes in your code and carefully reconcile them. COST/Trial BuildIT Automated Task Tool Its main purpose is to automate tasks, whether it is the final packaging of a product, an automated daily build, maybe sending out a mailing list, even backing-up files. Free C Sharper for VB Convert VB to C#. COST CLRProfiler Analyze and improve the behavior of your .NET app. Free CodeRush Direct competitor to ReSharper, contains similar feature. This is one of those decide for yourself. COST/Trial Disk2VHD Disk2vhd is a utility that creates VHD (Virtual Hard Disk - Microsoft's Virtual Machine disk format) versions of physical disks for use in Microsoft Virtual PC or Microsoft Hyper-V virtual machines (VMs). Free Eazfuscator.NET Is a free obfuscator for .NET. The main purpose is to protect intellectual property of software. Free EQATEC Profiler Make your .NET app run faster. No source code changes are needed. Just point the profiler to your app, run the modified code, and get a visual report. COST Expression Studio 3/4 Comes with Web, Blend, Sketch Flow and more. You can create websites, produce beautiful XAML and more. COST/Trial Expresso The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer or web designer with an extensive knowledge of regular expressions. Free Fiddler Fiddler is a web debugging proxy which logs all HTTP(s) traffic between your computer and the internet. Free Firebug Powerful Web development tool. If you build websites, you will need this. Free FxCop FxCop is an application that analyzes managed code assemblies (code that targets the .NET Framework common language runtime) and reports information about the assemblies, such as possible design, localization, performance, and security improvements. Free GAC Browser and Remover Easy way to remove multiple assemblies from the GAC. Assemblies registered by programs like Install Shield can also be removed. Free GAC Util The Global Assembly Cache tool allows you to view and manipulate the contents of the global assembly cache and download cache. Free HelpScribble Help Scribble is a full-featured, easy-to-use help authoring tool for creating help files from start to finish. You can create Win Help (.hlp) files, HTML Help (.chm) files, a printed manual and online documentation (on a web site) all from the same Help Scribble project. COST/Trial IETester IETester is a free Web Browser that allows you to have the rendering and JavaScript engines of IE9 preview, IE8, IE7 IE 6 and IE5.5 on Windows 7, Vista and XP, as well as the installed IE in the same process. Free iTextSharp iText# (iTextSharp) is a port of the iText open source java library for PDF generation written entirely in C# for the .NET platform. Use the iText mailing list to get support. Free Kaxaml Kaxaml is a lightweight XAML editor that gives you a "split view" so you can see both your XAML and your rendered content. Free LINQPad LinqPad lets you interactively query databases in a LINQ. Free Linquer Many programmers are familiar with SQL and will need a help in the transition to LINQ. Sometimes there are complicated queries to be written and Linqer can help by converting SQL scripts to LINQ. COST/Trial LiquidXML Liquid XML Studio 2010 is an advanced XML developers toolkit and IDE, containing all the tools needed for designing and developing XML schema and applications. COST/Trial Log4Net log4net is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent log4j framework to the .NET runtime. We have kept the framework similar in spirit to the original log4j while taking advantage of new features in the .NET runtime. For more information on log4net see the features document. Free Microsoft Web Platform Installer The Microsoft Web Platform Installer 2.0 (Web PI) is a free tool that makes getting the latest components of the Microsoft Web Platform, including Internet Information Services (IIS), SQL Server Express, .NET Framework and Visual Web Developer easy. Free Mono Development Don't have Visual Studio - no problem! This is an open Source C# and .NET development environment for Linux, Windows, and Mac OS X Free Net Mass Downloader While it’s great that Microsoft has released the .NET Reference Source Code, you can only get it one file at a time while you’re debugging. If you’d like to batch download it for reading or to populate the cache, you’d have to write a program that instantiated and called each method in the Framework Class Library. Fortunately, .NET Mass Downloader comes to the rescue! Free nMap Nmap ("Network Mapper") is a free and open source (license) utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Free NoScript (Firefox add-in) The NoScript Firefox extension provides extra protection for Firefox, Flock, Seamonkey and other Mozilla-based browsers: this free, open source add-on allows JavaScript, Java and Flash and other plug-ins to be executed only by trusted web sites of your choice (e.g. your online bank), and provides the most powerful Anti-XSS protection available in a browser. Free NotePad 2 Notepad2, a fast and light-weight Notepad-like text editor with syntax highlighting. This program can be run out of the box without installation, and does not touch your system's registry. Free PageSpy PageSpy is a small add-on for Internet Explorer that allows you to select any element within a webpage, select an option in the context menu, and view detailed information about both the coding behind the page and the element you selected. Free Phrase Express PhraseExpress manages your frequently used text snippets in customizable categories for quick access. Free PowerGui PowerGui is a free community for PowerGUI, a graphical user interface and script editor for Microsoft Windows PowerShell! Free Powershell Comes with Win7, but you can automate tasks by using the .NET Framework. Great for network admins. Free Process Explorer Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded. Also, included in the SysInterals Suite. Free Process Monitor Process Monitor is an advanced monitoring tool for Windows that shows real-time file system, Registry and process/thread activity. Free Reflector Explore and analyze compiled .NET assemblies, viewing them in C#, Visual Basic, and IL. This is an Essential for any .NET developer. Free Regular Expression Library Stuck on a Regular Expression but you think someone has already figured it out? Chances are they have. Free Regulator Regulator makes Regular Expressions easy. This is a must have for a .NET Developer. Free RenameMaestro RenameMaestro is probably the easiest batch file renamer you'll find to instantly rename multiple files COST ReSharper The one program that I cannot live without. Supports VS2010 and offers simple refactoring, code analysis/assistance/cleanup/templates. One of the few applications that is worth the $$$. COST/Trial ScrewTurn Wiki ScrewTurn Wiki allows you to create, manage and share wikis. A wiki is a collaboratively-edited, information-centered website: the most famous is Wikipedia. Free SharpDevelop What is #develop? SharpDevelop is a free IDE for C# and VB.NET projects on Microsoft's .NET platform. Free Show Me The Template Show Me The Template is a tool for exploring the templates, be their data, control or items panel, that comes with the controls built into WPF for all 6 themes. Free SnippetCompiler Compiles code snippets without opening Visual Studio. It does not support .NET 4. Free SQL Prompt SQL Prompt is a plug-in that increases how fast you can work with SQL. It provides code-completion for SQL server, reformatting, db schema information and snippets. Awesome! COST/Trial SQLinForm SQLinForm is an automatic SQL code formatter for all major databases  including ORACLE, SQL Server, DB2, UDB, Sybase, Informix, PostgreSQL, Teradata, MySQL, MS Access etc. with over 70 formatting options. COST/OnlineFree SSMS Tools SSMS Tools Pack is an add-in for Microsoft SQL Server Management Studio (SSMS) including SSMS Express. Free Storm STORM is a free and open source tool for testing web services. Free Telerik Code Convertor Convert code from VB to C Sharp and Vice Versa. Free TurtoiseSVN TortoiseSVN is a really easy to use Revision control / version control / source control software for Windows.Since it's not an integration for a specific IDE you can use it with whatever development tools you like. Free UltraEdit UltraEdit is the ideal text, HTML and hex editor, and an advanced PHP, Perl, Java and JavaScript editor for programmers. UltraEdit is also an XML editor including a tree-style XML parser. An industry-award winner, UltraEdit supports disk-based 64-bit file handling (standard) on 32-bit Windows platforms (Windows 2000 and later). COST/Trial Virtual Windows XP Comes with some W7 version and allows you to run WinXP along side W7. Free VirtualBox Virtualization by Sun Microsystems. You can virtualize Windows, Linux and more. Free Visual Log Parser SQL queries against a variety of log files and other system data sources. Free WinMerge WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle. Free Wireshark Wireshark is one of the best network protocol analyzer's for Unix and windows. This has been used several times to get me out of a bind. Free XML Notepad 07 Old, but still one of my favorite XML viewers. Free Productivity Tools – This is the list of tools that I use to save time or quickly navigate around Windows. Name Description License AutoHotKey Automate almost anything by sending keystrokes and mouse clicks. You can write a mouse or keyboard macro by hand or use the macro recorder. Free CLCL CLCL is clipboard caching utility. Free Ditto Ditto is an extension to the standard windows clipboard. It saves each item placed on the clipboard allowing you access to any of those items at a later time. Ditto allows you to save any type of information that can be put on the clipboard, text, images, html, custom formats, ..... Free Evernote Remember everything from notes to photos. It will synch between computers/devices. Free InfoRapid Inforapid is a search tool that will display all you search results in a html like browser. If you click on a word in that browser, it will start another search to the word you clicked on. Handy if you want to trackback something to it's true origin. The word you looked for will be highlighted in red. Clicking on the red word will open the containing file in a text based viewer. Clicking on any word in the opened document will start another search on that word. Free KatMouse The prime purpose of the KatMouse utility is to enhance the functionality of mice with a scroll wheel, offering 'universal' scrolling: moving the mouse wheel will scroll the window directly beneath the mouse cursor (not the one with the keyboard focus, which is default on Windows OSes). This is a major increase in the usefulness of the mouse wheel. Free ScreenR Instant Screencast with nothing to download. Works with Mac or PC and free. Free Start++ Start++ is an enhancement for the Start Menu in Windows Vista. It also extends the Run box and the command-line with customizable commands.  For example, typing "w Windows Vista" will take you to the Windows Vista page on Wikipedia! Free Synergy Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s). Free Texter Texter lets you define text substitution hot strings that, when triggered, will replace hotstring with a larger piece of text. By entering your most commonly-typed snippets of text into Texter, you can save countless keystrokes in the course of the day. Free Total Commander File handling, FTP, Archive handling and much more. Even works with Win3.11. COST/Trial Available Wizmouse WizMouse is a mouse enhancement utility that makes your mouse wheel work on the window currently under the mouse pointer, instead of the currently focused window. This means you no longer have to click on a window before being able to scroll it with the mouse wheel. This is a far more comfortable and practical way to make use of the mouse wheel. Free Xmarks Bookmark sync and search between computers. Free General Utilities – This is a list for power user users or anyone that wants more out of Windows. I usually install a majority of these whenever I get a new system. Name Description License µTorrent µTorrent is a lightweight and efficient BitTorrent client for Windows or Mac with many features. I use this for downloading LEGAL media. Free Audacity Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. Learn more about Audacity... Also check our Wiki and Forum for more information. Free AVast Free FREE Antivirus. Free CD Burner XP Pro CDBurnerXP is a free application to burn CDs and DVDs, including Blu-Ray and HD-DVDs. It also includes the feature to burn and create ISOs, as well as a multilanguage interface. Free CDEX You can extract digital audio CDs into mp3/wav. Free Combofix Combofix is a freeware (a legitimate spyware remover created by sUBs), Combofix was designed to scan a computer for known malware, spyware (SurfSideKick, QooLogic, and Look2Me as well as any other combination of the mentioned spyware applications) and remove them. Free Cpu-Z Provides information about some of the main devices of your system. Free Cropper Cropper is a screen capture utility written in C#. It makes it fast and easy to grab parts of your screen. Use it to easily crop out sections of vector graphic files such as Fireworks without having to flatten the files or open in a new editor. Use it to easily capture parts of a web site, including text and images. It's also great for writing documentation that needs images of your application or web site. Free DropBox Drag and Drop files to sync between computers. Free DVD-Fab Converts/Copies DVDs/Blu-Ray to different formats. (like mp4, mkv, avi) COST/Trial Available FastStone Capture FastStone Capture is a powerful, lightweight, yet full-featured screen capture tool that allows you to easily capture and annotate anything on the screen including windows, objects, menus, full screen, rectangular/freehand regions and even scrolling windows/web pages. Free ffdshow FFDShow is a DirectShow decoding filter for decompressing DivX, XviD, H.264, FLV1, WMV, MPEG-1 and MPEG-2, MPEG-4 movies. Free Filezilla FileZilla Client is a fast and reliable cross-platform FTP, FTPS and SFTP client with lots of useful features and an intuitive graphical user interface. You can also download a server version. Free FireFox Web Browser, do you really need an explanation? Free FireGestures A customizable mouse gestures extension which enables you to execute various commands and user scripts with five types of gestures. Free FoxIt Reader Light weight PDF viewer. You should install this with the advanced setting or it will install a toolbar and setup some shortcuts. Free gSynchIt Synch Gmail and Outlook. Even supports Outlook 2010 32/64 bit COST/Trial Available Hulu Desktop At home or in a hotel, this has replaced my cable/satellite subscription. Free ImgBurn ImgBurn is a lightweight CD / DVD / HD DVD / Blu-ray burning application that everyone should have in their toolkit! Free Infrarecorder InfraRecorder is a free CD/DVD burning solution for Microsoft Windows. It offers a wide range of powerful features; all through an easy to use application interface and Windows Explorer integration. Free KeePass KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. Free LastPass Another password management, synchronize between browsers, automatic form filling and more. Free Live Essentials One download and lots of programs including Mail, Live Writer, Movie Maker and more! Free Monitores MonitorES is a small windows utility that helps you to turnoff monitor display when you lock down your machine.Also when you lock your machine, it will pause all your running media programs & set your IM status message to "Away" / Custom message(via options) and restore it back to normal when you back. Free mRemote mRemote is a full-featured, multi-tab remote connections manager. Free Open Office OpenOffice.org 3 is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more. It is available in many languages and works on all common computers. It stores all your data in an international open standard format and can also read and write files from other common office software packages. It can be downloaded and used completely free of charge for any purpose. Free Paint.NET Simple, intuitive, and innovative user interface for editing photos. Free Picasa Picasa is free photo editing software from Google that makes your pictures look great. Free Pidgin Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once. Free PING PING is a live Linux ISO, based on the excellent Linux From Scratch (LFS) documentation. It can be burnt on a CD and booted, or integrated into a PXE / RIS environment. Free Putty PuTTY is an SSH and telnet client, developed originally by Simon Tatham for the Windows platform. Free Revo Uninstaller Revo Uninstaller Pro helps you to uninstall software and remove unwanted programs installed on your computer easily! Even if you have problems uninstalling and cannot uninstall them from "Windows Add or Remove Programs" control panel applet.Revo Uninstaller is a much faster and more powerful alternative to "Windows Add or Remove Programs" applet! It has very powerful features to uninstall and remove programs. Free Security Essentials Microsoft Security Essentials is a new, free consumer anti-malware solution for your computer. Free SetupVirtualCloneDrive Virtual CloneDrive works and behaves just like a physical CD/DVD drive, however it exists only virtually. Point to the .ISO file and it appears in Windows Explorer as a Drive. Free Shark 007 Codec Pack Play just about any file format with this download. Also includes my W7 Media Playlist Generator. Free Snagit 9 Screen Capture on steroids. Add arrows, captions, etc to any screenshot. COST/Trial Available SysinternalsSuite Go ahead and download the entire sys internals suite. I have mentioned multiple programs in this suite already. Free TeraCopy TeraCopy is a compact program designed to copy and move files at the maximum possible speed, providing the user with a lot of features. Free for Home TrueCrypt Free open-source disk encryption software for Windows 7/Vista/XP, Mac OS X, and Linux Free TweetDeck Fully featured Twitter client. Free UltraVNC UltraVNC is a powerful, easy to use and free software that can display the screen of another computer (via internet or network) on your own screen. The program allows you to use your mouse and keyboard to control the other PC remotely. It means that you can work on a remote computer, as if you were sitting in front of it, right from your current location. Free Unlocker Unlocks locked files. Pretty simple right? Free VLC Media Player VLC media player is a highly portable multimedia player and multimedia framework capable of reading most audio and video formats Free Windows 7 Media Playlist This program is special to my heart because I wrote it. It has been mentioned on podcast and various websites. It allows you to quickly create wvx video playlist for Windows Media Center. Free WinRAR WinRAR is a powerful archive manager. It can backup your data and reduce the size of email attachments, decompress RAR, ZIP and other files downloaded from Internet and create new archives in RAR and ZIP file format. COST/Trial Available Blogging – I use the following for my blog. Name Description License Insert Code for Windows Live Writer Insert Code for Windows Live Writer will format a snippet of text in a number of programming languages such as C#, HTML, MSH, JavaScript, Visual Basic and TSQL. Free LiveWriter Included in Live Essentials, but the ultimate in Windows Blogging Free PasteAsVSCode Plug-in for Windows Live Writer that pastes clipboard content as Visual Studio code. Preserves syntax highlighting, indentation and background color. Converts RTF, outputted by Visual Studio, into HTML. Free Desktop Management – The list below represent the best in Windows Desktop Management. Name Description License 7 Stacks Allows users to have "stacks" of icons in their taskbar. Free Executor Executor is a multi purpose launcher and a more advanced and customizable version of windows run. Free Fences Fences is a program that helps you organize your desktop and can hide your icons when they are not in use. Free RocketDock Rocket Dock is a smoothly animated, alpha blended application launcher. It provides a nice clean interface to drop shortcuts on for easy access and organization. With each item completely customizable there is no end to what you can add and launch from the dock. Free WindowsTab Tabbing is an essential feature of modern web browsers. Window Tabs brings the productivity of tabbed window management to all of your desktop applications. Free

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• C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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• Diving into OpenStack Network Architecture - Part 1

  - by Ronen Kofman

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} rkofman Normal rkofman 83 3045 2014-05-23T21:11:00Z 2014-05-27T06:58:00Z 3 1883 10739 Oracle Corporation 89 25 12597 12.00 140 Clean Clean false false false false EN-US X-NONE HE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} Before we begin OpenStack networking has very powerful capabilities but at the same time it is quite complicated. In this blog series we will review an existing OpenStack setup using the Oracle OpenStack Tech Preview and explain the different network components through use cases and examples. The goal is to show how the different pieces come together and provide a bigger picture view of the network architecture in OpenStack. This can be very helpful to users making their first steps in OpenStack or anyone wishes to understand how networking works in this environment.  We will go through the basics first and build the examples as we go. According to the recent Icehouse user survey and the one before it, Neutron with Open vSwitch plug-in is the most widely used network setup both in production and in POCs (in terms of number of customers) and so in this blog series we will analyze this specific OpenStack networking setup. As we know there are many options to setup OpenStack networking and while Neturon + Open vSwitch is the most popular setup there is no claim that it is either best or the most efficient option. Neutron + Open vSwitch is an example, one which provides a good starting point for anyone interested in understanding OpenStack networking. Even if you are using different kind of network setup such as different Neutron plug-in or even not using Neutron at all this will still be a good starting point to understand the network architecture in OpenStack. The setup we are using for the examples is the one used in the Oracle OpenStack Tech Preview. Installing it is simple and it would be helpful to have it as reference. In this setup we use eth2 on all servers for VM network, all VM traffic will be flowing through this interface.The Oracle OpenStack Tech Preview is using VLANs for L2 isolation to provide tenant and network isolation. The following diagram shows how we have configured our deployment: This first post is a bit long and will focus on some basic concepts in OpenStack networking. The components we will be discussing are Open vSwitch, network namespaces, Linux bridge and veth pairs. Note that this is not meant to be a comprehensive review of these components, it is meant to describe the component as much as needed to understand OpenStack network architecture. All the components described here can be further explored using other resources. Open vSwitch (OVS) In the Oracle OpenStack Tech Preview OVS is used to connect virtual machines to the physical port (in our case eth2) as shown in the deployment diagram. OVS contains bridges and ports, the OVS bridges are different from the Linux bridge (controlled by the brctl command) which are also used in this setup. To get started let’s view the OVS structure, use the following command: # ovs-vsctl show 7ec51567-ab42-49e8-906d-b854309c9edf     Bridge br-int         Port br-int             Interface br-int type: internal         Port "int-br-eth2"             Interface "int-br-eth2"     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2" ovs_version: "1.11.0" We see a standard post deployment OVS on a compute node with two bridges and several ports hanging off of each of them. The example above is a compute node without any VMs, we can see that the physical port eth2 is connected to a bridge called “br-eth2”. We also see two ports "int-br-eth2" and "phy-br-eth2" which are actually a veth pair and form virtual wire between the two bridges, veth pairs are discussed later in this post. When a virtual machine is created a port is created on one the br-int bridge and this port is eventually connected to the virtual machine (we will discuss the exact connectivity later in the series). Here is how OVS looks after a VM was launched: # ovs-vsctl show efd98c87-dc62-422d-8f73-a68c2a14e73d     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port br-int             Interface br-int type: internal         Port "qvocb64ea96-9f" tag: 1             Interface "qvocb64ea96-9f"     Bridge "br-eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2" ovs_version: "1.11.0" Bridge "br-int" now has a new port "qvocb64ea96-9f" which connects to the VM and tagged with VLAN 1. Every VM which will be launched will add a port on the “br-int” bridge for every network interface the VM has. Another useful command on OVS is dump-flows for example: # ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4): cookie=0x0, duration=735.544s, table=0, n_packets=70, n_bytes=9976, idle_age=17, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL cookie=0x0, duration=76679.786s, table=0, n_packets=0, n_bytes=0, idle_age=65534, hard_age=65534, priority=2,in_port=1 actions=drop cookie=0x0, duration=76681.36s, table=0, n_packets=68, n_bytes=7950, idle_age=17, hard_age=65534, priority=1 actions=NORMAL As we see the port which is connected to the VM has the VLAN tag 1. However the port on the VM network (eth2) will be using tag 1000. OVS is modifying the vlan as the packet flow from the VM to the physical interface. In OpenStack the Open vSwitch agent takes care of programming the flows in Open vSwitch so the users do not have to deal with this at all. If you wish to learn more about how to program the Open vSwitch you can read more about it at http://openvswitch.org looking at the documentation describing the ovs-ofctl command. Network Namespaces (netns) Network namespaces is a very cool Linux feature can be used for many purposes and is heavily used in OpenStack networking. Network namespaces are isolated containers which can hold a network configuration and is not seen from outside of the namespace. A network namespace can be used to encapsulate specific network functionality or provide a network service in isolation as well as simply help to organize a complicated network setup. Using the Oracle OpenStack Tech Preview we are using the latest Unbreakable Enterprise Kernel R3 (UEK3), this kernel provides a complete support for netns. Let's see how namespaces work through couple of examples to control network namespaces we use the ip netns command: Defining a new namespace: # ip netns add my-ns # ip netns list my-ns As mentioned the namespace is an isolated container, we can perform all the normal actions in the namespace context using the exec command for example running the ifconfig command: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:16436 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) We can run every command in the namespace context, this is especially useful for debug using tcpdump command, we can ping or ssh or define iptables all within the namespace. Connecting the namespace to the outside world: There are various ways to connect into a namespaces and between namespaces we will focus on how this is done in OpenStack. OpenStack uses a combination of Open vSwitch and network namespaces. OVS defines the interfaces and then we can add those interfaces to namespace. So first let's add a bridge to OVS: # ovs-vsctl add-br my-bridge Now let's add a port on the OVS and make it internal: # ovs-vsctl add-port my-bridge my-port # ovs-vsctl set Interface my-port type=internal And let's connect it into the namespace: # ip link set my-port netns my-ns Looking inside the namespace: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:65536 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) my-port   Link encap:Ethernet HWaddr 22:04:45:E2:85:21           BROADCAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) Now we can add more ports to the OVS bridge and connect it to other namespaces or other device like physical interfaces. Neutron is using network namespaces to implement network services such as DCHP, routing, gateway, firewall, load balance and more. In the next post we will go into this in further details. Linux Bridge and veth pairs Linux bridge is used to connect the port from OVS to the VM. Every port goes from the OVS bridge to a Linux bridge and from there to the VM. The reason for using regular Linux bridges is for security groups’ enforcement. Security groups are implemented using iptables and iptables can only be applied to Linux bridges and not to OVS bridges. Veth pairs are used extensively throughout the network setup in OpenStack and are also a good tool to debug a network problem. Veth pairs are simply a virtual wire and so veths always come in pairs. Typically one side of the veth pair will connect to a bridge and the other side to another bridge or simply left as a usable interface. In this example we will create some veth pairs, connect them to bridges and test connectivity. This example is using regular Linux server and not an OpenStack node: Creating a veth pair, note that we define names for both ends: # ip link add veth0 type veth peer name veth1 # ifconfig -a . . veth0     Link encap:Ethernet HWaddr 5E:2C:E6:03:D0:17           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) veth1     Link encap:Ethernet HWaddr E6:B6:E2:6D:42:B8           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) . . To make the example more meaningful this we will create the following setup: veth0 => veth1 => br-eth3 => eth3 ======> eth2 on another Linux server br-eth3 – a regular Linux bridge which will be connected to veth1 and eth3 eth3 – a physical interface with no IP on it, connected to a private network eth2 – a physical interface on the remote Linux box connected to the private network and configured with the IP of 50.50.50.1 Once we create the setup we will ping 50.50.50.1 (the remote IP) through veth0 to test that the connection is up: # brctl addbr br-eth3 # brctl addif br-eth3 eth3 # brctl addif br-eth3 veth1 # brctl show bridge name     bridge id               STP enabled     interfaces br-eth3         8000.00505682e7f6       no              eth3                                                         veth1 # ifconfig veth0 50.50.50.50 # ping -I veth0 50.50.50.51 PING 50.50.50.51 (50.50.50.51) from 50.50.50.50 veth0: 56(84) bytes of data. 64 bytes from 50.50.50.51: icmp_seq=1 ttl=64 time=0.454 ms 64 bytes from 50.50.50.51: icmp_seq=2 ttl=64 time=0.298 ms When the naming is not as obvious as the previous example and we don't know who are the paired veth interfaces we can use the ethtool command to figure this out. The ethtool command returns an index we can look up using ip link command, for example: # ethtool -S veth1 NIC statistics: peer_ifindex: 12 # ip link . . 12: veth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 Summary That’s all for now, we quickly reviewed OVS, network namespaces, Linux bridges and veth pairs. These components are heavily used in the OpenStack network architecture we are exploring and understanding them well will be very useful when reviewing the different use cases. In the next post we will look at how the OpenStack network is laid out connecting the virtual machines to each other and to the external world. @RonenKofman

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• How to shoot yourself in the foot (DO NOT Read in the office)

  - by TATWORTH

  Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2013/06/21/how-to-shoot-yourself-in-the-foot-do-not-read.aspxLet me make it absolutely clear - the following is:merely collated by your Geek from http://www.codeproject.com/Lounge.aspx?msg=3917012#xx3917012xxvery, very very funny so you read it in the presence of others at your own riskso here is the list - you have been warned!C You shoot yourself in the foot.   C++ You accidently create a dozen instances of yourself and shoot them all in the foot. Providing emergency medical assistance is impossible since you can't tell which are bitwise copies and which are just pointing at others and saying "That's me, over there."   FORTRAN You shoot yourself in each toe, iteratively, until you run out of toes, then you read in the next foot and repeat. If you run out of bullets, you continue anyway because you have no exception-handling facility.   Modula-2 After realizing that you can't actually accomplish anything in this language, you shoot yourself in the head.   COBOL USEing a COLT 45 HANDGUN, AIM gun at LEG.FOOT, THEN place ARM.HAND.FINGER on HANDGUN.TRIGGER and SQUEEZE. THEN return HANDGUN to HOLSTER. CHECK whether shoelace needs to be retied.   Lisp You shoot yourself in the appendage which holds the gun with which you shoot yourself in the appendage which holds the gun with which you shoot yourself in the appendage which holds...   BASIC Shoot yourself in the foot with a water pistol. On big systems, continue until entire lower body is waterlogged.   Forth Foot yourself in the shoot.   APL You shoot yourself in the foot; then spend all day figuring out how to do it in fewer characters.   Pascal The compiler won't let you shoot yourself in the foot.   Snobol If you succeed, shoot yourself in the left foot. If you fail, shoot yourself in the right foot.   HyperTalk Put the first bullet of the gun into foot left of leg of you. Answer the result.   Prolog You tell your program you want to be shot in the foot. The program figures out how to do it, but the syntax doesn't allow it to explain.   370 JCL You send your foot down to MIS with a 4000-page document explaining how you want it to be shot. Three years later, your foot comes back deep-fried.   FORTRAN-77 You shoot yourself in each toe, iteratively, until you run out of toes, then you read in the next foot and repeat. If you run out of bullets, you continue anyway because you still can't do exception-processing.   Modula-2 (alternative) You perform a shooting on what might be currently a foot with what might be currently a bullet shot by what might currently be a gun.   BASIC (compiled) You shoot yourself in the foot with a BB using a SCUD missile launcher.   Visual Basic You'll really only appear to have shot yourself in the foot, but you'll have so much fun doing it that you won't care.   Forth (alternative) BULLET DUP3 * GUN LOAD FOOT AIM TRIGGER PULL BANG! EMIT DEAD IF DROP ROT THEN (This takes about five bytes of memory, executes in two to ten clock cycles on any processor and can be used to replace any existing function of the language as well as in any future words). (Welcome to bottom up programming - where you, too, can perform compiler pre-processing instead of writing code)   APL (alternative) You hear a gunshot and there's a hole in your foot, but you don't remember enough linear algebra to understand what happened. or @#&^$%&%^ foot   Pascal (alternative) Same as Modula-2 except that the bullet is not the right type for the gun and your hand is blown off.   Snobol (alternative) You grab your foot with your hand, then rewrite your hand to be a bullet. The act of shooting the original foot then changes your hand/bullet into yet another foot (a left foot).   Prolog (alternative) You attempt to shoot yourself in the foot, but the bullet, failing to find its mark, backtracks to the gun, which then explodes in your face.   COMAL You attempt to shoot yourself in the foot with a water pistol, but the bore is clogged, and the pressure build-up blows apart both the pistol and your hand. or draw_pistol aim_at_foot(left) pull_trigger hop(swearing)   Scheme As Lisp, but none of the other appendages are aware of this happening.   Algol You shoot yourself in the foot with a musket. The musket is aesthetically fascinating and the wound baffles the adolescent medic in the emergency room.   Ada If you are dumb enough to actually use this language, the United States Department of Defense will kidnap you, stand you up in front of a firing squad and tell the soldiers, "Shoot at the feet." or The Department of Defense shoots you in the foot after offering you a blindfold and a last cigarette. or After correctly packaging your foot, you attempt to concurrently load the gun, pull the trigger, scream and shoot yourself in the foot. When you try, however, you discover that your foot is of the wrong type. or After correctly packing your foot, you attempt to concurrently load the gun, pull the trigger, scream, and confidently aim at your foot knowing it is safe. However the cordite in the round does an Unchecked Conversion, fires and shoots you in the foot anyway.   Eiffel   You create a GUN object, two FOOT objects and a BULLET object. The GUN passes both the FOOT objects a reference to the BULLET. The FOOT objects increment their hole counts and forget about the BULLET. A little demon then drives a garbage truck over your feet and grabs the bullet (both of it) on the way. Smalltalk You spend so much time playing with the graphics and windowing system that your boss shoots you in the foot, takes away your workstation and makes you develop in COBOL on a character terminal. or You send the message shoot to gun, with selectors bullet and myFoot. A window pops up saying Gunpowder doesNotUnderstand: spark. After several fruitless hours spent browsing the methods for Trigger, FiringPin and IdealGas, you take the easy way out and create ShotFoot, a subclass of Foot with an additional instance variable bulletHole. Object Oriented Pascal You perform a shooting on what might currently be a foot with what might currently be a bullet fired from what might currently be a gun.   PL/I You consume all available system resources, including all the offline bullets. The Data Processing & Payroll Department doubles its size, triples its budget, acquires four new mainframes and drops the original one on your foot. Postscript foot bullets 6 locate loadgun aim gun shoot showpage or It takes the bullet ten minutes to travel from the gun to your foot, by which time you're long since gone out to lunch. The text comes out great, though.   PERL You stab yourself in the foot repeatedly with an incredibly large and very heavy Swiss Army knife. or You pick up the gun and begin to load it. The gun and your foot begin to grow to huge proportions and the world around you slows down, until the gun fires. It makes a tiny hole, which you don't feel. Assembly Language You crash the OS and overwrite the root disk. The system administrator arrives and shoots you in the foot. After a moment of contemplation, the administrator shoots himself in the foot and then hops around the room rabidly shooting at everyone in sight. or You try to shoot yourself in the foot only to discover you must first reinvent the gun, the bullet, and your foot.or The bullet travels to your foot instantly, but it took you three weeks to load the round and aim the gun.   BCPL You shoot yourself somewhere in the leg -- you can't get any finer resolution than that. Concurrent Euclid You shoot yourself in somebody else's foot.   Motif You spend days writing a UIL description of your foot, the trajectory, the bullet and the intricate scrollwork on the ivory handles of the gun. When you finally get around to pulling the trigger, the gun jams.   Powerbuilder While attempting to load the gun you discover that the LoadGun system function is buggy; as a work around you tape the bullet to the outside of the gun and unsuccessfully attempt to fire it with a nail. In frustration you club your foot with the butt of the gun and explain to your client that this approximates the functionality of shooting yourself in the foot and that the next version of Powerbuilder will fix it.   Standard ML By the time you get your code to typecheck, you're using a shoot to foot yourself in the gun.   MUMPS You shoot 583149 AK-47 teflon-tipped, hollow-point, armour-piercing bullets into even-numbered toes on odd-numbered feet of everyone in the building -- with one line of code. Three weeks later you shoot yourself in the head rather than try to modify that line.   Java You locate the Gun class, but discover that the Bullet class is abstract, so you extend it and write the missing part of the implementation. Then you implement the ShootAble interface for your foot, and recompile the Foot class. The interface lets the bullet call the doDamage method on the Foot, so the Foot can damage itself in the most effective way. Now you run the program, and call the doShoot method on the instance of the Gun class. First the Gun creates an instance of Bullet, which calls the doFire method on the Gun. The Gun calls the hit(Bullet) method on the Foot, and the instance of Bullet is passed to the Foot. But this causes an IllegalHitByBullet exception to be thrown, and you die.   Unix You shoot yourself in the foot or % ls foot.c foot.h foot.o toe.c toe.o % rm * .o rm: .o: No such file or directory % ls %   370 JCL (alternative) You shoot yourself in the head just thinking about it.   DOS JCL You first find the building you're in in the phone book, then find your office number in the corporate phone book. Then you have to write this down, then describe, in cubits, your exact location, in relation to the door (right hand side thereof). Then you need to write down the location of the gun (loading it is a proprietary utility), then you load it, and the COBOL program, and run them, and, with luck, it may be run tonight.   VMS   $ MOUNT/DENSITY=.45/LABEL=BULLET/MESSAGE="BYE" BULLET::BULLET$GUN SYS$BULLET $ SET GUN/LOAD/SAFETY=OFF/SIGHT=NONE/HAND=LEFT/CHAMBER=1/ACTION=AUTOMATIC/ LOG/ALL/FULL SYS$GUN_3$DUA3:[000000]GUN.GNU $ SHOOT/LOG/AUTO SYS$GUN SYS$SYSTEM:[FOOT]FOOT.FOOT   %DCL-W-ACTIMAGE, error activating image GUN -CLI-E-IMGNAME, image file $3$DUA240:[GUN]GUN.EXE;1 -IMGACT-F-NOTNATIVE, image is not an OpenVMS Alpha AXP image or %SYS-F-FTSHT, foot shot (fifty lines of traceback omitted) sh,csh, etc You can't remember the syntax for anything, so you spend five hours reading manual pages, then your foot falls asleep. You shoot the computer and switch to C.   Apple System 7 Double click the gun icon and a window giving a selection for guns, target areas, plus balloon help with medical remedies, and assorted sound effects. Click "shoot" button and a small bomb appears with note "Error of Type 1 has occurred."   Windows 3.1 Double click the gun icon and wait. Eventually a window opens giving a selection for guns, target areas, plus balloon help with medical remedies, and assorted sound effects. Click "shoot" button and a small box appears with note "Unable to open Shoot.dll, check that path is correct."   Windows 95 Your gun is not compatible with this OS and you must buy an upgrade and install it before you can continue. Then you will be informed that you don't have enough memory.   CP/M I remember when shooting yourself in the foot with a BB gun was a big deal.   DOS You finally found the gun, but can't locate the file with the foot for the life of you.   MSDOS You shoot yourself in the foot, but can unshoot yourself with add-on software.   Access You try to point the gun at your foot, but it shoots holes in all your Borland distribution diskettes instead.   Paradox Not only can you shoot yourself in the foot, your users can too.   dBase You squeeze the trigger, but the bullet moves so slowly that by the time your foot feels the pain, you've forgotten why you shot yourself anyway. or You buy a gun. Bullets are only available from another company and are promised to work so you buy them. Then you find out that the next version of the gun is the one scheduled to actually shoot bullets.   DBase IV, V1.0 You pull the trigger, but it turns out that the gun was a poorly designed hand grenade and the whole building blows up.   SQL You cut your foot off, send it out to a service bureau and when it returns, it has a hole in it but will no longer fit the attachment at the end of your leg. or Insert into Foot Select Bullet >From Gun.Hand Where Chamber = 'LOADED' And Trigger = 'PULLED'   Clipper You grab a bullet, get ready to insert it in the gun so that you can shoot yourself in the foot and discover that the gun that the bullets fits has not yet been built, but should be arriving in the mail _REAL_SOON_NOW_. Oracle The menus for coding foot_shooting have not been implemented yet and you can't do foot shooting in SQL.   English You put your foot in your mouth, then bite it off. (For those who don't know, English is a McDonnell Douglas/PICK query language which allegedly requires 110% of system resources to run happily.) Revelation [an implementation of the PICK Operating System] You'll be able to shoot yourself in the foot just as soon as you figure out what all these bullets are for.   FlagShip Starting at the top of your head, you aim the gun at yourself repeatedly until, half an hour later, the gun is finally pointing at your foot and you pull the trigger. A new foot with a hole in it appears but you can't work out how to get rid of the old one and your gun doesn't work anymore.   FidoNet You put your foot in your mouth, then echo it internationally.   PicoSpan [a UNIX-based computer conferencing system] You can't shoot yourself in the foot because you're not a host. or (host variation) Whenever you shoot yourself in the foot, someone opens a topic in policy about it.   Internet You put your foot in your mouth, shoot it, then spam the bullet so that everybody gets shot in the foot.   troff rmtroff -ms -Hdrwp | lpr -Pwp2 & .*place bullet in footer .B .NR FT +3i .in 4 .bu Shoot! .br .sp .in -4 .br .bp NR HD -2i .*   Genetic Algorithms You create 10,000 strings describing the best way to shoot yourself in the foot. By the time the program produces the optimal solution, humans have evolved wings and the problem is moot.   CSP (Communicating Sequential Processes) You only fail to shoot everything that isn't your foot.   MS-SQL Server MS-SQL Server’s gun comes pre-loaded with an unlimited supply of Teflon coated bullets, and it only has two discernible features: the muzzle and the trigger. If that wasn't enough, MS-SQL Server also puts the gun in your hand, applies local anesthetic to the skin of your forefinger and stitches it to the gun's trigger. Meanwhile, another process has set up a spinal block to numb your lower body. It will then proceeded to surgically remove your foot, cryogenically freeze it for preservation, and attach it to the muzzle of the gun so that no matter where you aim, you will shoot your foot. In order to avoid shooting yourself in the foot, you need to unstitch your trigger finger, remove your foot from the muzzle of the gun, and have it surgically reattached. Then you probably want to get some crutches and go out to buy a book on SQL Server Performance Tuning.   Sybase Sybase's gun requires assembly, and you need to go out and purchase your own clip and bullets to load the gun. Assembly is complicated by the fact that Sybase has hidden the gun behind a big stack of reference manuals, but it hasn't told you where that stack is. While you were off finding the gun, assembling it, buying bullets, etc., Sybase was also busy surgically removing your foot and cryogenically freezing it for preservation. Instead of attaching it to the muzzle of the gun, though, it packed your foot on dry ice and sent it UPS-Ground to an unnamed hookah bar somewhere in the middle east. In order to shoot your foot, you must modify your gun with a GPS system for targeting and hire some guy named "Indy" to find the hookah bar and wire the coordinates back to you. By this time, you've probably become so daunted at the tasks stand between you and shooting your foot that you hire a guy who's read all the books on Sybase to help you shoot your foot. If you're lucky, he'll be smart enough both to find your foot and to stop you from shooting it.   Magic software You spend 1 week looking up the correct syntax for GUN. When you find it, you realise that GUN will not let you shoot in your own foot. It will allow you to shoot almost anything but your foot. You then decide to build your own gun. You can't use the standard barrel since this will only allow for standard bullets, which will not fire if the barrel is pointed at your foot. After four weeks, you have created your own custom gun. It blows up in your hand without warning, because you failed to initialise the safety catch and it doesn't know whether the initial state is "0", 0, NULL, "ZERO", 0.0, 0,0, "0.0", or "0,00". You fix the problem with your remaining hand by nesting 12 safety catches, and then decide to build the gun without safety catch. You then shoot the management and retire to a happy life where you code in languages that will allow you to shoot your foot in under 10 days.FirefoxLets you shoot yourself in as many feet as you'd like, while using multiple great addons! IEA moving target in terms of standard ammunition size and doesn't always work properly with non-Microsoft ammunition, so sometimes you shoot something other than your foot. However, it's the corporate world's standard foot-shooting apparatus. Hackers seem to enjoy rigging websites up to trigger cascading foot-shooting failures. Windows 98 About the same as Windows 95 in terms of overall bullet capacity and triggering mechanisms. Includes updated DirectShot API. A new version was released later on to support USB guns, Windows 98 SE.WPF:You get your baseball glove and a ball and you head out to your backyard, where you throw balls to your pitchback. Then your unkempt-haired-cargo-shorts-and-sandals-with-white-socks-wearing neighbor uses XAML to sculpt your arm into a gun, the ball into a bullet and the pitchback into your foot. By now, however, only the neighbor can get it to work and he's only around from 6:30 PM - 3:30 AM. LOGO: You very carefully lay out the trajectory of the bullet. Then you start the gun, which fires very slowly. You walk precisely to the point where the bullet will travel and wait, but just before it gets to you, your class time is up and one of the other kids has already used the system to hack into Sony's PS3 network. Flash: Someone has designed a beautiful-looking gun that anyone can shoot their feet with for free. It weighs six hundred pounds. All kinds of people are shooting themselves in the feet, and sending the link to everyone else so that they can too. That is, except for the criminals, who are all stealing iOS devices that the gun won't work with.APL: Its (mostly) all greek to me. Lisp: Place ((gun in ((hand sight (foot then shoot))))) (Lots of Insipid Stupid Parentheses)Apple OS/X and iOS Once a year, Steve Jobs returns from sick leave to tell millions of unwavering fans how they will be able to shoot themselves in the foot differently this year. They retweet and blog about it ad nauseam, and wait in line to be the first to experience "shoot different".Windows ME Usually fails, even at shooting you in the foot. Yo dawg, I heard you like shooting yourself in the foot. So I put a gun in your gun, so you can shoot yourself in the foot while you shoot yourself in the foot. (Okay, I'm not especially proud of this joke.) Windows 2000 Now you really do have to log in, before you are allowed to shoot yourself in the foot.Windows XPYou thought you learned your lesson: Don't use Windows ME. Then, along came this new creature, built on top of Windows NT! So you spend the next couple days installing antivirus software, patches and service packs, just so you can get that driver to install, and then proceed to shoot yourself in the foot. Windows Vista Newer! Glossier! Shootier! Windows 7 The bullets come out a lot smoother. Active Directory Each bullet now has an attached Bullet Identifier, and can be uniquely identified. Policies can be applied to dictate fragmentation, and the gun will occasionally have a confusing delay after the trigger has been pulled. PythonYou try to use import foot; foot.shoot() only to realize that's only available in 3.0, to which you can't yet upgrade from 2.7 because of all those extension libs lacking support. Solaris Shoots best when used on SPARC hardware, but still runs the trigger GUI under Java. After weeks of learning the appropriate STOP command to prevent the trigger from automatically being pressed on boot, you think you've got it under control. Then the one time you ever use dtrace, it hits a bug that fires the gun. MySQL The feature that allows you to shoot yourself in the foot has been in development for about 6 years, and they are adding it into the next version, which is coming out REAL SOON NOW, promise! But you can always check it out of source control and try it yourself (just not in any environment where data integrity is important because it will probably explode.) PostgreSQLAllows you to have a smug look on your face while you shoot yourself in the foot, because those MySQL guys STILL don't have that feature. NoSQL Barrel? Who needs a barrel? Just put the bullet on your foot, and strike it with a hammer. See? It's so much simpler and more efficient that way. You can even strike multiple bullets in one swing if you swing with a good enough arc, because hammers are easy to use. Getting them to synchronize is a little difficult, though.Eclipse There are about a dozen different packages for shooting yourself in the foot, with weird interdependencies on outdated components. Once you finally navigate the morass and get one installed, you then have something to look at while you shoot yourself in the foot with that package: You can watch the screen redraw.Outlook Makes it really easy to let everyone know you shot yourself in the foot!Shooting yourself in the foot using delegates.You really need to shoot yourself in the foot but you hate firearms (you don't want any dependency on the specifics of shooting) so you delegate it to somebody else. You don't care how it is done as long is shooting your foot. You can do it asynchronously in case you know you may faint so you are called back/slapped in the face by your shooter/friend (or background worker) when everything is done.C#You prepare the gun and the bullet, carefully modeling all of the physics of a bullet traveling through a foot. Just before you're about to pull the trigger, you stumble on System.Windows.BodyParts.Foot.ShootAt(System.Windows.Firearms.IGun gun) in the extended framework, realize you just wasted the entire afternoon, and shoot yourself in the head.PHP<?phprequire("foot_safety_check.php");?><!DOCTYPE HTML><html><head> <!--Lower!--><title>Shooting me in the foot</title></head> <body> <!--LOWER!!!--><leg> <!--OK, I made this one up...--><footer><?php echo (dungSift($_SERVER['HTTP_USER_AGENT'], "ie"))?("Your foot is safe, but you might want to wear a hard hat!"):("<div class=\"shot\">BANG!</div>"); ?></footer></leg> </body> </html>

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• Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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• Async ignored on AJAX requests on Nginx server

  - by eComEvo

  Despite sending an async request to the server over AJAX, the server will not respond until the previous unrelated request has finished. The following code is only broken in this way on Nginx, but runs perfectly on Apache. This call will start a background process and it waits for it to complete so it can display the final result. $.ajax({ type: 'GET', async: true, url: $(this).data('route'), data: $('input[name=data]').val(), dataType: 'json', success: function (data) { /* do stuff */} error: function (data) { /* handle errors */} }); The below is called after the above, which on Apache requires 100ms to execute and repeats itself, showing progress for data being written in the background: checkStatusInterval = setInterval(function () { $.ajax({ type: 'GET', async: false, cache: false, url: '/process-status?process=' + currentElement.attr('id'), dataType: 'json', success: function (data) { /* update progress bar and status message */ } }); }, 1000); Unfortunately, when this script is run from nginx, the above progress request never even finishes a single request until the first AJAX request that sent the data is done. If I change the async to TRUE in the above, it executes one every interval, but none of them complete until that very first AJAX request finishes. Here is the main nginx conf file: #user nobody; worker_processes 1; #error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error.log info; #pid logs/nginx.pid; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; server_names_hash_bucket_size 64; # configure temporary paths # nginx is started with param -p, setting nginx path to serverpack installdir fastcgi_temp_path temp/fastcgi; uwsgi_temp_path temp/uwsgi; scgi_temp_path temp/scgi; client_body_temp_path temp/client-body 1 2; proxy_temp_path temp/proxy; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; #access_log logs/access.log main; # Sendfile copies data between one FD and other from within the kernel. # More efficient than read() + write(), since the requires transferring data to and from the user space. sendfile on; # Tcp_nopush causes nginx to attempt to send its HTTP response head in one packet, # instead of using partial frames. This is useful for prepending headers before calling sendfile, # or for throughput optimization. tcp_nopush on; # don't buffer data-sends (disable Nagle algorithm). Good for sending frequent small bursts of data in real time. tcp_nodelay on; types_hash_max_size 2048; # Timeout for keep-alive connections. Server will close connections after this time. keepalive_timeout 90; # Number of requests a client can make over the keep-alive connection. This is set high for testing. keepalive_requests 100000; # allow the server to close the connection after a client stops responding. Frees up socket-associated memory. reset_timedout_connection on; # send the client a "request timed out" if the body is not loaded by this time. Default 60. client_header_timeout 20; client_body_timeout 60; # If the client stops reading data, free up the stale client connection after this much time. Default 60. send_timeout 60; # Size Limits client_body_buffer_size 64k; client_header_buffer_size 4k; client_max_body_size 8M; # FastCGI fastcgi_connect_timeout 60; fastcgi_send_timeout 120; fastcgi_read_timeout 300; # default: 60 secs; when step debugging with XDEBUG, you need to increase this value fastcgi_buffer_size 64k; fastcgi_buffers 4 64k; fastcgi_busy_buffers_size 128k; fastcgi_temp_file_write_size 128k; # Caches information about open FDs, freqently accessed files. open_file_cache max=200000 inactive=20s; open_file_cache_valid 30s; open_file_cache_min_uses 2; open_file_cache_errors on; # Turn on gzip output compression to save bandwidth. # http://wiki.nginx.org/HttpGzipModule gzip on; gzip_disable "MSIE [1-6]\.(?!.*SV1)"; gzip_http_version 1.1; gzip_vary on; gzip_proxied any; #gzip_proxied expired no-cache no-store private auth; gzip_comp_level 6; gzip_buffers 16 8k; gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/javascript; # show all files and folders autoindex on; server { # access from localhost only listen 127.0.0.1:80; server_name localhost; root www; # the following default "catch-all" configuration, allows access to the server from outside. # please ensure your firewall allows access to tcp/port 80. check your "skype" config. # listen 80; # server_name _; log_not_found off; charset utf-8; access_log logs/access.log main; # handle files in the root path /www location / { index index.php index.html index.htm; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root www; } # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 # location ~ \.php$ { try_files $uri =404; fastcgi_pass 127.0.0.1:9100; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } # add expire headers location ~* ^.+.(gif|ico|jpg|jpeg|png|flv|swf|pdf|mp3|mp4|xml|txt|js|css)$ { expires 30d; } # deny access to .htaccess files (if Apache's document root concurs with nginx's one) # deny access to git & svn repositories location ~ /(\.ht|\.git|\.svn) { deny all; } } # include config files of "enabled" domains include domains-enabled/*.conf; } Here is the enabled domain conf file: access_log off; access_log C:/server/www/test.dev/logs/access.log; error_log C:/server/www/test.dev/logs/error.log; # HTTP Server server { listen 127.0.0.1:80; server_name test.dev; root C:/server/www/test.dev/public; index index.php; rewrite_log on; default_type application/octet-stream; #include /etc/nginx/mime.types; # Include common configurations. include domains-common/location.conf; } # HTTPS server server { listen 443 ssl; server_name test.dev; root C:/server/www/test.dev/public; index index.php; rewrite_log on; default_type application/octet-stream; #include /etc/nginx/mime.types; # Include common configurations. include domains-common/location.conf; include domains-common/ssl.conf; } Contents of ssl.conf: # OpenSSL for HTTPS connections. ssl on; ssl_certificate C:/server/bin/openssl/certs/cert.pem; ssl_certificate_key C:/server/bin/openssl/certs/cert.key; ssl_session_timeout 5m; ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers HIGH:!aNULL:!MD5; ssl_prefer_server_ciphers on; # Pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 location ~ \.php$ { try_files $uri =404; fastcgi_param HTTPS on; fastcgi_pass 127.0.0.1:9100; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } Contents of location.conf: # Remove trailing slash to please Laravel routing system. if (!-d $request_filename) { rewrite ^/(.+)/$ /$1 permanent; } location / { try_files $uri $uri/ /index.php?$query_string; } # We don't need .ht files with nginx. location ~ /(\.ht|\.git|\.svn) { deny all; } # Added cache headers for images. location ~* \.(png|jpg|jpeg|gif)$ { expires 30d; log_not_found off; } # Only 3 hours on CSS/JS to allow me to roll out fixes during early weeks. location ~* \.(js|css)$ { expires 3h; log_not_found off; } # Add expire headers. location ~* ^.+.(gif|ico|jpg|jpeg|png|flv|swf|pdf|mp3|mp4|xml|txt)$ { expires 30d; } # Pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 location ~ \.php$ { try_files $uri /index.php =404; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; fastcgi_pass 127.0.0.1:9100; } Any ideas where this is going wrong?

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• Need guidance on a Google Map application that has to show 250 000 polylines.

  - by lucian.jp

  I am looking for advice for an application I am developing that uses Google Map. Summary: A user has a list of criteria for searching a street segment that fulfills the criteria. The street segments will be colored with 3 colors for showing those below average, average and over average. Then the user clicks on the street segment to see an information window showing the properties of that specific segment hiding those not selected until he/she closes the window and other polyline becomes visible again. This looks quite like the Monopoly City Streets game Hasbro made some month ago the difference being I do not use Flash, I can’t use Open Street Map because it doesn’t list street segment (if it does the IDs won’t be the same anyway) and I do not have to show Google sketch building over. Information: I have a database of street segments with IDs, polyline points and centroid. The database has 6,000,000 street segment records in it. To narrow the generated data a bit we focus on city. The largest city we must show has 250,000 street segments. This means 250,000 line segment polyline to show. Our longest polyline uses 9600 characters which is stored in two 8000 varchar columns in SQL Server 2008. We need to use the API v3 because it is faster than the API v2 and the application will be ported to iPhone. For now it's an ASP.NET 3.5 with SQl Server 2008 application. Performance is a priority. Problems: Most of the demo projects that do this are made with API v2. So besides tutorial on the Google API v3 reference page I have nothing to compare performance or technology use to achieve my goal. There is no available .NET wrapper for the API v3 yet. Generating a 250,000 line segment polyline creates a heavy file which takes time to transfer and parse. (I have found a demo of one polyline of 390,000 points. I think the encoder would be far less efficient with more polylines with less points since there will be less rounding.) Since streets segments are shown based on criteria, polylines must be dynamically created and cache can't be used. Some thoughts: KML/KMZ: Pros: Since it is a standard we can easily load Bing maps, Yahoo! maps, Google maps, Google Earth, with the same KML file. The data generation would be the same. Cons: LineString in KML cannot be encoded polyline like the Google map API can handle. So it would probably be bigger and slower to display. Zipping the file at the size it will take more processing time and require the client side to uncompress the data and I am not quite sure with 250,000 data how an iPhone would handle this and how a server would handle 40 users browsing at the same time. JavaScript file: Pros: JavaScript file can have encoded polyline and would significantly reduce the file to transfer. Cons: Have to create my own stripped version of API v3 to add overlays, create polyline, etc. It is more complex than just create a KML file and point to the source. GeoRSS: This option isn't adapted for my needs I think, but I could be wrong. MapServer: I saw some post suggesting using MapServer to generate overlays. Not quite sure for the connection with our database and the performance it would give. Plus it requires a plugin for generating KML. It seems to me that it wouldn't allow me to do better than creating my own KML or JavaScript file. Maintenance would be simpler without. Monopoly City Streets: The game is now over, but for those who know what I am talking about Monopoly City Streets was showing at max zoom level only the streets that the centroid was inside the Bounds of the window. Moving the map was sending request to the server for the new streets to show. While I think this was ingenious, I have no idea how to implement something similar. The only thing I thought about was to compare if the long was inside the bound of map area X and same with Y. While this could improve performance significantly at high zoom level, this would give nothing when showing a whole city. Clustering: While cluster is awesome for marker, it seems we cannot cluster polylines. I would have liked something like MarkerClusterer for polylines and be able to cluster by my 3 polyline colors. This will probably stay as a “would have been freaking awesome but forget it”. Arrow: I will have in a future version to show a direction for the polyline and will have to show an arrow at the centroid. Loading an image or marker will only double my data so creating a custom overlay will probably be my only option. I have found that demo for something similar I would like to achieve. Unfortunately, the demo is very slow, but I only wish to show 1 arrow per polyline and not multiple like the demo. This functionality will depend on the format of data since I don't think KML support custom overlays. Criteria: While the application is done with ASP.NET 3.5, the port to the iPhone won't use the web to show the application and be limited in screen size for selecting the criteria. This is why I was more orienting on a service or page generating the file based on criteria passed in parameters. The service would than generate the file I need to display the polylines on the map. I could also create an aspx page that does this. The aspx page is more documented than the service way. There should be a reason. Questions: Should I create a web service to returns the street segments file or create an aspx page that return the file? Should I create a JavaScript file with encoded polyline or a KML with longitude/latitude based on the fact that maximum longitude/latitude polyline have 9600 characters and I have to render maximum 250,000 line segment polyline. Or should I go with a MapServer that generate the overlay? Will I be able to display simple arrow on the polyline on the next version. In case of KML generation is it faster to create the file with XDocument, XmlDocument, XmlWriter and this manually or just serialize the street segment in the stream? This is more a brainstorming Stack Overflow question than an actual code problem. Any answer helping narrow the possibilities is as good as someone having all the knowledge to point me out a better choice.

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• is this correct use of jquery's document.ready?

  - by Haroldo

  The below file contains all the javascript for a page. Performance is the highest priority. Is this the most efficient way? Do all click/hover events need to to be inside the doc.ready? //DOCUMENT.READY EVENTS //--------------------------------------------------------------------------- $(function(){ // mark events as not loaded $('.event').data({ t1_loaded: false, t2_loaded: false, t3_loaded: false, art_req: false }); //mark no events have been clicked $('#wrap_right').data('first_click_made', false); // cal-block event click $('#cal_blocks div.event, #main_search div.event').live('click', function(){ var id = $(this).attr('id').split('e')[1]; event_click(id); }); // jq history $.historyInit(function(hash){ if(hash) { event_click(hash); } }); // search $('#search_input').typeWatch ({ callback: function(){ var q = $('#search_input').attr('value'); search(q); }, wait : 350, highlight : false, captureLength : 2 }); $('#search_input, #main_search div.close').live('click',function(){ $(this).attr("value",""); reset_srch_res(); }); $('#main_search').easydrag(); $('a.dialog').colorbox(); //TAB CLICK -> AJAX LOAD TAB $('#wrap_right .rs_tabs li').live('click', function(){ $this = $(this); var id = $('#wrap_right').data('curr_event'); var tab = parseInt($this.attr('rel')); //hide other tabs $('#rs_'+id+' .tab_body').hide(); //mark current(clicked) tab $('#rs_'+id+' .rs_tabs li').removeClass('curr_tab'); $this.addClass('curr_tab'); //is the tab already loaded and hidden? var loaded = $('#e'+id).data('t'+tab+'_loaded'); //console.log('id: '+id+', tab: '+tab+', loaded: '+loaded); if(loaded === true) { $('#rs_'+id+' .tab'+tab).show(); if (tab == 2) { art_requested(id); } } else { //ajax load in the tab $('#rs_'+id+' .tab'+tab).load('index_files/tab'+tab+'.php?id='+id, function(){ //after load callback if (tab == 1) { $('#rs_' + id + ' .frame').delay(600).fadeIn(600) }; if (tab == 2) { art_requested(id); } }); //mark tab as loaded $('#e'+id).data('t'+tab+'_loaded', true); //fade in current tab $('#rs_'+id+' .tab'+tab).show(); } }) }); // LOAD RS FUNCTIONS //--------------------------------------------------------------------------- function event_click(id){ window.location.hash = id; //mark current event $('#wrap_right').data('curr_event', id); //hide any other events if($('#wrap_right').data('first_click_made') === true) { $('#wrap_right .event_rs').hide(); } //frame loaded before? var loaded = $('#e'+id).data('t1_loaded'); if(loaded === true) { $('#rs_'+id).show(); } else { create_frame(id); } //open/load the first tab $('#rs_'+id+' .t1').click(); $('#wrap_right').data('first_click_made', true); $('#cal_blocks').scrollTo('#e'+id, 1000, {offset: {top:-220, left:0}}); } function create_frame(id){ var art = ents[id].art; var ven = ents[id].ven; var type = ents[id].gig_club; //select colours for tabs if(type == 1){ var label = 'gig';} else if(type == 2){ var label = 'club';} else if(type == 0){ var label = 'other';} //create rs container for this event var frame = '<div id="rs_'+id+'" class="event_rs">'; frame += '<div class="title_strip"></div>'; frame += '<div class="rs_tabs"><ul class="'+label+'"><li class="t1 nav_tab1 curr_tab hand" rel="1"></li>'; if(art == 1){frame += '<li class="t2 nav_tab2 hand" rel="2"></li>';} if(ven == 1){frame += '<li class="t3 nav_tab2 hand" rel="3"></li>';} frame += '</ul></div>'; frame += '<div id="rs_content"><div class="tab_body tab1" ></div>'; if(art == 1){frame += '<div class="tab_body tab2"></div>';} if(ven == 1){frame += '<div class="tab_body tab3"></div>';} frame += '</div>'; frame += '</div>'; $('#wrap_right').append(frame); //mark current event in cal-blocks $('#cal_blocks .event_sel').removeClass('event_sel'); $('#e'+id).addClass('event_sel'); if($('#wrap_right').data('first_click_made') === false) { $('#wrap_right').delay(500).slideDown(); $('#rs_'+id+' .rs_tabs').delay(800).fadeIn(); } }; // FUNCTIONS //--------------------------------------------------------------------------- //check to see if an artist has been requested function art_requested(id){ var art_req = $('#e'+id).data('art_req'); if(art_req !== false) { //alert(art_req); $('#art_'+art_req).click(); } } //scroll artist panes smoothly (scroll bars cause glitches otherwise) function before (){ if(!IE){$('#art_scrollable .bio_etc').css('overflow','-moz-scrollbars-none');} } function after (){ if(!IE){$('#art_scrollable .bio_etc').css('overflow','auto');} } function prep_media_carousel(){ //youtube and soundcloud player $("#rs_content .yt_scrollable a.yt, #rs_content .yt_scrollable a.sc").colorbox({ overlayClose : false, opacity : 0 }); $("#colorbox").easydrag(true); $('#cboxOverlay').remove(); } function make_carousel_scrollable(unique_id){ $('#scroll_'+unique_id).scrollable({ size:1, clickable:false, nextPage:'#r_'+unique_id, prevPage:'#l_'+unique_id }); } function check_l_r_arrows(total, counter, art_id){ //left arrow if(counter > 0) { $('#l_'+art_id).show(); $('#l_'+art_id+'_inactive').hide(); } else { $('#l_'+art_id).hide(); $('#l_'+art_id+'_inactive').show(); } //right arrow if(counter < total-3) { $('#r_'+art_id).show(); $('#r_'+art_id+'_inactive').hide(); } else { $('#r_'+art_id).hide(); $('#r_'+art_id+'_inactive').show(); } } function reset_srch_res(){ $('#main_search').fadeOut(400).children().remove(); } function search(q){ $.ajax({ type: 'GET', url: 'index_files/srch/search.php?q='+q, success: function(e) { $('#main_search').html(e).show(); } }); }

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• Increase efficiency of a loop with jQuery

  - by Pez Cuckow

  I have a game coded in jQuery where bots are moved around the screen. The below code is a loop that runs every 20ms, currently if you have over 15 bots you start to notice the browser lagging (simply because of all the advanced collision detection going on). Is there any way to reduce the lag, can I make it any more efficient? P.s. sorrry for just posting a block of code, I can't see a way to make my point clear enough without! $.playground().registerCallback(function(){ //Movement Loop if(!pause) { for (var i in bots) { //bots - color, dir, x, y, z, spawned?, spawnerid, prevd var self = $('#b' + i); var current = bots[i]; if(bots[i][5]==1) { var xspeed = 0, yspeed = 0; if(current[1]==0) { yspeed = -D_SPEED; } else if(current[1]==1) { xspeed = D_SPEED; } else if(current[1]==2) { yspeed = D_SPEED; } else if(current[1]==3) { xspeed = -D_SPEED; } var x = current[2] + xspeed; var y = current[3] + yspeed; var z = current[3] + 120; if(current[2]>0&&x>PLAYGROUND_WIDTH||current[2]<0&&x<-GRID_SIZE|| current[3]>0&&y>PLAYGROUND_HEIGHT||current[3]<0&&y<-GRID_SIZE) { remove_bot(i, self); } else { if(current[7]!=current[1]) { self.setAnimation(colors[current[0]][current[1]]); bots[i][7] = current[1]; } if(self.css({"left": ""+(x)+"px", "top": ""+(y)+"px", "z-index": z})) { bots[i][2] = x; bots[i][3] = y; bots[i][4] = z; bots[i][8]++; } } } } $("#debug").html(dump(arrows)); $(".bot").each(function(){ var b_id = $(this).attr("id").substr(1); var collision = false; var c_bot = bots[b_id]; var b_x = c_bot[2]; var b_y = c_bot[3]; var b_d = c_bot[1]; $(this).collision(".arrow,#arrows").each(function(){ //Many thanks to Selim Arsever for this fix! var a_id = $(this).attr("id").substr(1); var piece = arrows[a_id]; var a_v = piece[0]; if(a_v==1) { var a_x = piece[2]; var a_y = piece[3]; var d_x = b_x-a_x; var d_y = b_y-a_y; if(d_x>=4&&d_x<=5&&d_y>=1&&d_y<=2) { //bots - color, dir, x, y, z, spawned?, spawnerid, prevd bots[b_id][7] = c_bot[1]; bots[b_id][1] = piece[1]; collision = true; } } }); if(!collision) { $(this).collision(".wall,#level").each(function(){ var w_id = $(this).attr("id").substr(1); var piece = pieces[w_id]; var w_x = piece[1]; var w_y = piece[2]; d_x = b_x-w_x; d_y = b_y-w_y; if(b_d==0&&d_x>=4&&d_x<=5&&d_y>=27&&d_y<=28) { kill_bot(b_id); collision = true; } //4 // 33 if(b_d==1&&d_x>=-12&&d_x<=-11&&d_y>=21&&d_y<=22) { kill_bot(b_id); collision = true; } //-14 // 21 if(b_d==2&&d_x>=4&&d_x<=5&&d_y>=-9&&d_y<=-8) { kill_bot(b_id); collision = true; } //4 // -9 if(b_d==3&&d_x>=22&&d_x<=23&&d_y>=20&&d_y<=21) { kill_bot(b_id); collision = true; } //22 // 21 }); } if(!collision&&c_bot[8]>GRID_MOVE) { $(this).collision(".spawn,#level").each(function(){ var s_id = $(this).attr("id").substr(1); var piece = pieces[s_id]; var s_x = piece[1]; var s_y = piece[2]; d_x = b_x-s_x; d_y = b_y-s_y; if(b_d==0&&d_x>=4&&d_x<=5&&d_y>=19&&d_y<=20) { kill_bot(b_id); collision = true; } //4 // 33 if(b_d==1&&d_x>=-14&&d_x<=-13&&d_y>=11&&d_y<=12) { kill_bot(b_id); collision = true; } //-14 // 21 if(b_d==2&&d_x>=4&&d_x<=5&&d_y>=-11&&d_y<=-10) { kill_bot(b_id); collision = true; } //4 // -9 if(b_d==3&&d_x>=22&&d_x<=23&&d_y>=11&&d_y<=12) { kill_bot(b_id); collision = true; } //22 // 21*/ }); } if(!collision) { $(this).collision(".exit,#level").each(function(){ var e_id = $(this).attr("id").substr(1); var piece = pieces[e_id]; var e_x = piece[1]; var e_y = piece[2]; d_x = b_x-e_x; d_y = b_y-e_y; if(d_x>=4&&d_x<=5&&d_y>=1&&d_y<=2) { current_bots++; bots[b_id] = false; $("#current_bots").html(current_bots); $("#b" + b_id).setAnimation(exit[2], function(node){$(node).fadeOut(200)}); } }); } if(!collision) { $(this).collision(".bot,#level").each(function(){ var bd_id = $(this).attr("id").substr(1); if(bd_id!=b_id) { var piece = bots[bd_id]; var bd_x = piece[2]; var bd_y = piece[3]; d_x = b_x-bd_x; d_y = b_y-bd_y; if(d_x>=0&&d_x<=2&&d_y>=0&&d_y<=2) { kill_bot(b_id); kill_bot(bd_id); collision = true; } } }); } }); } }, REFRESH_RATE); Many thanks,

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• Optimizing a lot of Scanner.findWithinHorizon(pattern, 0) calls

  - by darvids0n

  I'm building a process which extracts data from 6 csv-style files and two poorly laid out .txt reports and builds output CSVs, and I'm fully aware that there's going to be some overhead searching through all that whitespace thousands of times, but I never anticipated converting about about 50,000 records would take 12 hours. Excerpt of my manual matching code (I know it's horrible that I use lists of tokens like that, but it was the best thing I could think of): public static String lookup(List<String> tokensBefore, List<String> tokensAfter) { String result = null; while(_match(tokensBefore)) { // block until all input is read if(id.hasNext()) { result = id.next(); // capture the next token that matches if(_matchImmediate(tokensAfter)) // try to match tokensAfter to this result return result; } else return null; // end of file; no match } return null; // no matches } private static boolean _match(List<String> tokens) { return _match(tokens, true); } private static boolean _match(List<String> tokens, boolean block) { if(tokens != null && !tokens.isEmpty()) { if(id.findWithinHorizon(tokens.get(0), 0) == null) return false; for(int i = 1; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(id.hasNext() && !id.next().matches(tokens.get(i))) { break; // break to blocking behaviour } } } else { return true; // empty list always matches } if(block) return _match(tokens); // loop until we find something or nothing else return false; // return after just one attempted match } private static boolean _matchImmediate(List<String> tokens) { if(tokens != null) { for(int i = 0; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(!id.hasNext() || !id.next().matches(tokens.get(i))) { return false; // doesn't match, or end of file } } return false; // we have some serious problems if this ever gets called } else { return true; // empty list always matches } } Basically wondering how I would work in an efficient string search (Boyer-Moore or similar). My Scanner id is scanning a java.util.String, figured buffering it to memory would reduce I/O since the search here is being performed thousands of times on a relatively small file. The performance increase compared to scanning a BufferedReader(FileReader(File)) was probably less than 1%, the process still looks to be taking a LONG time. I've also traced execution and the slowness of my overall conversion process is definitely between the first and last like of the lookup method. In fact, so much so that I ran a shortcut process to count the number of occurrences of various identifiers in the .csv-style files (I use 2 lookup methods, this is just one of them) and the process completed indexing approx 4 different identifiers for 50,000 records in less than a minute. Compared to 12 hours, that's instant. Some notes (updated): I don't necessarily need the pattern-matching behaviour, I only get the first field of a line of text so I need to match line breaks or use Scanner.nextLine(). All ID numbers I need start at position 0 of a line and run through til the first block of whitespace, after which is the name of the corresponding object. I would ideally want to return a String, not an int locating the line number or start position of the result, but if it's faster then it will still work just fine. If an int is being returned, however, then I would now have to seek to that line again just to get the ID; storing the ID of every line that is searched sounds like a way around that. Anything to help me out, even if it saves 1ms per search, will help, so all input is appreciated. Thankyou! Usage scenario 1: I have a list of objects in file A, who in the old-style system have an id number which is not in file A. It is, however, POSSIBLY in another csv-style file (file B) or possibly still in a .txt report (file C) which each also contain a bunch of other information which is not useful here, and so file B needs to be searched through for the object's full name (1 token since it would reside within the second column of any given line), and then the first column should be the ID number. If that doesn't work, we then have to split the search token by whitespace into separate tokens before doing a search of file C for those tokens as well. Generalised code: String field; for (/* each record in file A */) { /* construct the rest of this object from file A info */ // now to find the ID, if we can List<String> objectName = new ArrayList<String>(1); objectName.add(Pattern.quote(thisObject.fullName)); field = lookup(objectSearchToken, objectName); // search file B if(field == null) // not found in file B { lookupReset(false); // initialise scanner to check file C objectName.clear(); // not using the full name String[] tokens = thisObject.fullName.split(id.delimiter().pattern()); for(String s : tokens) objectName.add(Pattern.quote(s)); field = lookup(objectSearchToken, objectName); // search file C lookupReset(true); // back to file B } else { /* found it, file B specific processing here */ } if(field != null) // found it in B or C thisObject.ID = field; } The objectName tokens are all uppercase words with possible hyphens or apostrophes in them, separated by spaces. Much like a person's name. As per a comment, I will pre-compile the regex for my objectSearchToken, which is just [\r\n]+. What's ending up happening in file C is, every single line is being checked, even the 95% of lines which don't contain an ID number and object name at the start. Would it be quicker to use ^[\r\n]+.*(objectname) instead of two separate regexes? It may reduce the number of _match executions. The more general case of that would be, concatenate all tokensBefore with all tokensAfter, and put a .* in the middle. It would need to be matching backwards through the file though, otherwise it would match the correct line but with a huge .* block in the middle with lots of lines. The above situation could be resolved if I could get java.util.Scanner to return the token previous to the current one after a call to findWithinHorizon. I have another usage scenario. Will put it up asap.

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• Non recursive way to position a genogram in 2D points for x axis. Descendant are below

  - by Nassign

  I currently was tasked to make a genogram for a family consisting of siblings, parents with aunts and uncles with grandparents and greatgrandparents for only blood relatives. My current algorithm is using recursion. but I am wondering how to do it in non recursive way to make it more efficient. it is programmed in c# using graphics to draw on a bitmap. Current algorithm for calculating x position, the y position is by getting the generation number. public void StartCalculatePosition() { // Search the start node (The only node with targetFlg set to true) Person start = null; foreach (Person p in PersonDic.Values) { if (start == null) start = p; if (p.Targetflg) { start = p; break; } } CalcPositionRecurse(start); // Normalize the position (shift all values to positive value) // Get the minimum value (must be negative) // Then offset the position of all marriage and person with that to make it start from zero float minPosition = float.MaxValue; foreach (Person p in PersonDic.Values) { if (minPosition > p.Position) { minPosition = p.Position; } } if (minPosition < 0) { foreach (Person p in PersonDic.Values) { p.Position -= minPosition; } foreach (Marriage m in MarriageList) { m.ParentsPosition -= minPosition; m.ChildrenPosition -= minPosition; } } } /// <summary> /// Calculate position of genogram using recursion /// </summary> /// <param name="psn"></param> private void CalcPositionRecurse(Person psn) { // End the recursion if (psn.BirthMarriage == null || psn.BirthMarriage.Parents.Count == 0) { psn.Position = 0.0f; if (psn.BirthMarriage != null) { psn.BirthMarriage.ParentsPosition = 0.0f; psn.BirthMarriage.ChildrenPosition = 0.0f; } CalculateSiblingPosition(psn); return; } // Left recurse if (psn.Father != null) { CalcPositionRecurse(psn.Father); } // Right recurse if (psn.Mother != null) { CalcPositionRecurse(psn.Mother); } // Merge Position if (psn.Father != null && psn.Mother != null) { AdjustConflict(psn.Father, psn.Mother); // Position person in center of parent psn.Position = (psn.Father.Position + psn.Mother.Position) / 2; psn.BirthMarriage.ParentsPosition = psn.Position; psn.BirthMarriage.ChildrenPosition = psn.Position; } else { // Single mom or single dad if (psn.Father != null) { psn.Position = psn.Father.Position; psn.BirthMarriage.ParentsPosition = psn.Position; psn.BirthMarriage.ChildrenPosition = psn.Position; } else if (psn.Mother != null) { psn.Position = psn.Mother.Position; psn.BirthMarriage.ParentsPosition = psn.Position; psn.BirthMarriage.ChildrenPosition = psn.Position; } else { // Should not happen, checking in start of function } } // Arrange the siblings base on my position (left younger, right older) CalculateSiblingPosition(psn); } private float GetRightBoundaryAncestor(Person psn) { float rPos = psn.Position; // Get the rightmost position among siblings foreach (Person sibling in psn.Siblings) { if (sibling.Position > rPos) { rPos = sibling.Position; } } if (psn.Father != null) { float rFatherPos = GetRightBoundaryAncestor(psn.Father); if (rFatherPos > rPos) { rPos = rFatherPos; } } if (psn.Mother != null) { float rMotherPos = GetRightBoundaryAncestor(psn.Mother); if (rMotherPos > rPos) { rPos = rMotherPos; } } return rPos; } private float GetLeftBoundaryAncestor(Person psn) { float rPos = psn.Position; // Get the rightmost position among siblings foreach (Person sibling in psn.Siblings) { if (sibling.Position < rPos) { rPos = sibling.Position; } } if (psn.Father != null) { float rFatherPos = GetLeftBoundaryAncestor(psn.Father); if (rFatherPos < rPos) { rPos = rFatherPos; } } if (psn.Mother != null) { float rMotherPos = GetLeftBoundaryAncestor(psn.Mother); if (rMotherPos < rPos) { rPos = rMotherPos; } } return rPos; } /// <summary> /// Check if two parent group has conflict and compensate on the conflict /// </summary> /// <param name="leftGroup"></param> /// <param name="rightGroup"></param> public void AdjustConflict(Person leftGroup, Person rightGroup) { float leftMax = GetRightBoundaryAncestor(leftGroup); leftMax += 0.5f; float rightMin = GetLeftBoundaryAncestor(rightGroup); rightMin -= 0.5f; float diff = leftMax - rightMin; if (diff > 0.0f) { float moveHalf = Math.Abs(diff) / 2; RecurseMoveAncestor(leftGroup, 0 - moveHalf); RecurseMoveAncestor(rightGroup, moveHalf); } } /// <summary> /// Recursively move a person and all his/her ancestor /// </summary> /// <param name="psn"></param> /// <param name="moveUnit"></param> public void RecurseMoveAncestor(Person psn, float moveUnit) { psn.Position += moveUnit; foreach (Person siblings in psn.Siblings) { if (siblings.Id != psn.Id) { siblings.Position += moveUnit; } } if (psn.BirthMarriage != null) { psn.BirthMarriage.ChildrenPosition += moveUnit; psn.BirthMarriage.ParentsPosition += moveUnit; } if (psn.Father != null) { RecurseMoveAncestor(psn.Father, moveUnit); } if (psn.Mother != null) { RecurseMoveAncestor(psn.Mother, moveUnit); } } /// <summary> /// Calculate the position of the siblings /// </summary> /// <param name="psn"></param> /// <param name="anchor"></param> public void CalculateSiblingPosition(Person psn) { if (psn.Siblings.Count == 0) { return; } List<Person> sibling = psn.Siblings; int argidx; for (argidx = 0; argidx < sibling.Count; argidx++) { if (sibling[argidx].Id == psn.Id) { break; } } // Compute position for each brother that is younger that person int idx; for (idx = argidx - 1; idx >= 0; idx--) { sibling[idx].Position = sibling[idx + 1].Position - 1; } for (idx = argidx + 1; idx < sibling.Count; idx++) { sibling[idx].Position = sibling[idx - 1].Position + 1; } }

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• Inserting Records in Ascending Order function- C homework assignment

  - by Aaron McRuer

  Good day, Stack Overflow. I have a homework assignment that I'm working on this weekend that I'm having a bit of a problem with. We have a struct "Record" (which contains information about cars for a dealership) that gets placed in a particular spot in a linked list according to 1) its make and 2) according to its model year. This is done when initially building the list, when a "int insertRecordInAscendingOrder" function is called in Main. In "insertRecordInAscendingOrder", a third function, "createRecord" is called, where the linked list is created. The function then goes to the function "compareCars" to determine what elements get put where. Depending on the value returned by this function, insertRecordInAscendingOrder then places the record where it belongs. The list is then printed out. There's more to the assignment, but I'll cross that bridge when I come to it. Ideally, and for the assignment to be considered correct, the linked list must be ordered as: Chevrolet 2012 25 Chevrolet 2013 10 Ford 2010 5 Ford 2011 3 Ford 2012 15 Honda 2011 9 Honda 2012 3 Honda 2013 12 Toyota 2009 2 Toyota 2011 7 Toyota 2013 20 from the a text file that has the data ordered the following way: Ford 2012 15 Ford 2011 3 Ford 2010 5 Toyota 2011 7 Toyota 2012 20 Toyota 2009 2 Honda 2011 9 Honda 2012 3 Honda 2013 12 Chevrolet 2013 10 Chevrolet 2012 25 Notice that the alphabetical order of the "make" field takes precedence, then, the model year is arranged from oldest to newest. However, the program produces this as the final list: Chevrolet 2012 25 Chevrolet 2013 10 Honda 2011 9 Honda 2012 3 Honda 2013 12 Toyota 2009 2 Toyota 2011 7 Toyota 2012 20 Ford 2010 5 Ford 2011 3 Ford 2012 15 I sat down with a grad student and tried to work out all of this yesterday, but we just couldn't figure out why it was kicking the Ford nodes down to the end of the list. Here's the code. As you'll notice, I included a printList call at each instance of the insertion of a node. This way, you can see just what is happening when the nodes are being put in "order". It is in ANSI C99. All function calls must be made as they are specified, so unfortunately, there's no real way of getting around this problem by creating a more efficient algorithm. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LINE 50 #define MAX_MAKE 20 typedef struct record { char *make; int year; int stock; struct record *next; } Record; int compareCars(Record *car1, Record *car2); void printList(Record *head); Record* createRecord(char *make, int year, int stock); int insertRecordInAscendingOrder(Record **head, char *make, int year, int stock); int main(int argc, char **argv) { FILE *inFile = NULL; char line[MAX_LINE + 1]; char *make, *yearStr, *stockStr; int year, stock, len; Record* headRecord = NULL; /*Input and file diagnostics*/ if (argc!=2) { printf ("Filename not provided.\n"); return 1; } if((inFile=fopen(argv[1], "r"))==NULL) { printf("Can't open the file\n"); return 2; } /*obtain values for linked list*/ while (fgets(line, MAX_LINE, inFile)) { make = strtok(line, " "); yearStr = strtok(NULL, " "); stockStr = strtok(NULL, " "); year = atoi(yearStr); stock = atoi(stockStr); insertRecordInAscendingOrder(&headRecord,make, year, stock); } printf("The original list in ascending order: \n"); printList(headRecord); } /*use strcmp to compare two makes*/ int compareCars(Record *car1, Record *car2) { int compStrResult; compStrResult = strcmp(car1->make, car2->make); int compYearResult = 0; if(car1->year > car2->year) { compYearResult = 1; } else if(car1->year == car2->year) { compYearResult = 0; } else { compYearResult = -1; } if(compStrResult == 0 ) { if(compYearResult == 1) { return 1; } else if(compYearResult == -1) { return -1; } else { return compStrResult; } } else if(compStrResult == 1) { return 1; } else { return -1; } } int insertRecordInAscendingOrder(Record **head, char *make, int year, int stock) { Record *previous = *head; Record *newRecord = createRecord(make, year, stock); Record *current = *head; int compResult; if(*head == NULL) { *head = newRecord; printf("Head is null, list was empty\n"); printList(*head); return 1; } else if ( compareCars(newRecord, *head)==-1) { *head = newRecord; (*head)->next = current; printf("New record was less than the head, replacing\n"); printList(*head); return 1; } else { printf("standard case, searching and inserting\n"); previous = *head; while ( current != NULL &&(compareCars(newRecord, current)==1)) { printList(*head); previous = current; current = current->next; } printList(*head); previous->next = newRecord; previous->next->next = current; } return 1; } /*creates records from info passed in from main via insertRecordInAscendingOrder.*/ Record* createRecord(char *make, int year, int stock) { printf("CreateRecord\n"); Record *theRecord; int len; if(!make) { return NULL; } theRecord = malloc(sizeof(Record)); if(!theRecord) { printf("Unable to allocate memory for the structure.\n"); return NULL; } theRecord->year = year; theRecord->stock = stock; len = strlen(make); theRecord->make = malloc(len + 1); strncpy(theRecord->make, make, len); theRecord->make[len] = '\0'; theRecord->next=NULL; return theRecord; } /*prints list. lists print.*/ void printList(Record *head) { int i; int j = 50; Record *aRecord; aRecord = head; for(i = 0; i < j; i++) { printf("-"); } printf("\n"); printf("%20s%20s%10s\n", "Make", "Year", "Stock"); for(i = 0; i < j; i++) { printf("-"); } printf("\n"); while(aRecord != NULL) { printf("%20s%20d%10d\n", aRecord->make, aRecord->year, aRecord->stock); aRecord = aRecord->next; } printf("\n"); } The text file you'll need for a command line argument can be saved under any name you like; here are the contents you'll need: Ford 2012 15 Ford 2011 3 Ford 2010 5 Toyota 2011 7 Toyota 2012 20 Toyota 2009 2 Honda 2011 9 Honda 2012 3 Honda 2013 12 Chevrolet 2013 10 Chevrolet 2012 25 Thanks in advance for your help. I shall continue to plow away at it myself.

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• Increase efficiency of a loop with jQuery and GameQuery

  - by Pez Cuckow

  I have a game coded in jQuery where bots are moved around the screen. The below code is a loop that runs every 20ms, currently if you have over 15 bots you start to notice the browser lagging (simply because of all the advanced collision detection going on). Is there any way to reduce the lag, can I make it any more efficient? P.s. sorrry for just posting a block of code, I can't see a way to make my point clear enough without! $.playground().registerCallback(function(){ //Movement Loop if(!pause) { for (var i in bots) { //bots - color, dir, x, y, z, spawned?, spawnerid, prevd var self = $('#b' + i); var current = bots[i]; if(bots[i][5]==1) { var xspeed = 0, yspeed = 0; if(current[1]==0) { yspeed = -D_SPEED; } else if(current[1]==1) { xspeed = D_SPEED; } else if(current[1]==2) { yspeed = D_SPEED; } else if(current[1]==3) { xspeed = -D_SPEED; } var x = current[2] + xspeed; var y = current[3] + yspeed; var z = current[3] + 120; if(current[2]>0&&x>PLAYGROUND_WIDTH||current[2]<0&&x<-GRID_SIZE|| current[3]>0&&y>PLAYGROUND_HEIGHT||current[3]<0&&y<-GRID_SIZE) { remove_bot(i, self); } else { if(current[7]!=current[1]) { self.setAnimation(colors[current[0]][current[1]]); bots[i][7] = current[1]; } if(self.css({"left": ""+(x)+"px", "top": ""+(y)+"px", "z-index": z})) { bots[i][2] = x; bots[i][3] = y; bots[i][4] = z; bots[i][8]++; } } } } $("#debug").html(dump(arrows)); $(".bot").each(function(){ var b_id = $(this).attr("id").substr(1); var collision = false; var c_bot = bots[b_id]; var b_x = c_bot[2]; var b_y = c_bot[3]; var b_d = c_bot[1]; $(this).collision(".arrow,#arrows").each(function(){ //Many thanks to Selim Arsever for this fix! var a_id = $(this).attr("id").substr(1); var piece = arrows[a_id]; var a_v = piece[0]; if(a_v==1) { var a_x = piece[2]; var a_y = piece[3]; var d_x = b_x-a_x; var d_y = b_y-a_y; if(d_x>=4&&d_x<=5&&d_y>=1&&d_y<=2) { //bots - color, dir, x, y, z, spawned?, spawnerid, prevd bots[b_id][7] = c_bot[1]; bots[b_id][1] = piece[1]; collision = true; } } }); if(!collision) { $(this).collision(".wall,#level").each(function(){ var w_id = $(this).attr("id").substr(1); var piece = pieces[w_id]; var w_x = piece[1]; var w_y = piece[2]; d_x = b_x-w_x; d_y = b_y-w_y; if(b_d==0&&d_x>=4&&d_x<=5&&d_y>=27&&d_y<=28) { kill_bot(b_id); collision = true; } //4 // 33 if(b_d==1&&d_x>=-12&&d_x<=-11&&d_y>=21&&d_y<=22) { kill_bot(b_id); collision = true; } //-14 // 21 if(b_d==2&&d_x>=4&&d_x<=5&&d_y>=-9&&d_y<=-8) { kill_bot(b_id); collision = true; } //4 // -9 if(b_d==3&&d_x>=22&&d_x<=23&&d_y>=20&&d_y<=21) { kill_bot(b_id); collision = true; } //22 // 21 }); } if(!collision&&c_bot[8]>GRID_MOVE) { $(this).collision(".spawn,#level").each(function(){ var s_id = $(this).attr("id").substr(1); var piece = pieces[s_id]; var s_x = piece[1]; var s_y = piece[2]; d_x = b_x-s_x; d_y = b_y-s_y; if(b_d==0&&d_x>=4&&d_x<=5&&d_y>=19&&d_y<=20) { kill_bot(b_id); collision = true; } //4 // 33 if(b_d==1&&d_x>=-14&&d_x<=-13&&d_y>=11&&d_y<=12) { kill_bot(b_id); collision = true; } //-14 // 21 if(b_d==2&&d_x>=4&&d_x<=5&&d_y>=-11&&d_y<=-10) { kill_bot(b_id); collision = true; } //4 // -9 if(b_d==3&&d_x>=22&&d_x<=23&&d_y>=11&&d_y<=12) { kill_bot(b_id); collision = true; } //22 // 21*/ }); } if(!collision) { $(this).collision(".exit,#level").each(function(){ var e_id = $(this).attr("id").substr(1); var piece = pieces[e_id]; var e_x = piece[1]; var e_y = piece[2]; d_x = b_x-e_x; d_y = b_y-e_y; if(d_x>=4&&d_x<=5&&d_y>=1&&d_y<=2) { current_bots++; bots[b_id] = false; $("#current_bots").html(current_bots); $("#b" + b_id).setAnimation(exit[2], function(node){$(node).fadeOut(200)}); } }); } if(!collision) { $(this).collision(".bot,#level").each(function(){ var bd_id = $(this).attr("id").substr(1); if(bd_id!=b_id) { var piece = bots[bd_id]; var bd_x = piece[2]; var bd_y = piece[3]; d_x = b_x-bd_x; d_y = b_y-bd_y; if(d_x>=0&&d_x<=2&&d_y>=0&&d_y<=2) { kill_bot(b_id); kill_bot(bd_id); collision = true; } } }); } }); } }, REFRESH_RATE); Many thanks,

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• Handling inheritance with overriding efficiently

  - by Fyodor Soikin

  I have the following two data structures. First, a list of properties applied to object triples: Object1 Object2 Object3 Property Value O1 O2 O3 P1 "abc" O1 O2 O3 P2 "xyz" O1 O3 O4 P1 "123" O2 O4 O5 P1 "098" Second, an inheritance tree: O1 O2 O4 O3 O5 Or viewed as a relation: Object Parent O2 O1 O4 O2 O3 O1 O5 O3 O1 null The semantics of this being that O2 inherits properties from O1; O4 - from O2 and O1; O3 - from O1; and O5 - from O3 and O1, in that order of precedence. NOTE 1: I have an efficient way to select all children or all parents of a given object. This is currently implemented with left and right indexes, but hierarchyid could also work. This does not seem important right now. NOTE 2: I have tiggers in place that make sure that the "Object" column always contains all possible objects, even when they do not really have to be there (i.e. have no parent or children defined). This makes it possible to use inner joins rather than severely less effiecient outer joins. The objective is: Given a pair of (Property, Value), return all object triples that have that property with that value either defined explicitly or inherited from a parent. NOTE 1: An object triple (X,Y,Z) is considered a "parent" of triple (A,B,C) when it is true that either X = A or X is a parent of A, and the same is true for (Y,B) and (Z,C). NOTE 2: A property defined on a closer parent "overrides" the same property defined on a more distant parent. NOTE 3: When (A,B,C) has two parents - (X1,Y1,Z1) and (X2,Y2,Z2), then (X1,Y1,Z1) is considered a "closer" parent when: (a) X2 is a parent of X1, or (b) X2 = X1 and Y2 is a parent of Y1, or (c) X2 = X1 and Y2 = Y1 and Z2 is a parent of Z1 In other words, the "closeness" in ancestry for triples is defined based on the first components of the triples first, then on the second components, then on the third components. This rule establishes an unambigous partial order for triples in terms of ancestry. For example, given the pair of (P1, "abc"), the result set of triples will be: O1, O2, O3 -- Defined explicitly O1, O2, O5 -- Because O5 inherits from O3 O1, O4, O3 -- Because O4 inherits from O2 O1, O4, O5 -- Because O4 inherits from O2 and O5 inherits from O3 O2, O2, O3 -- Because O2 inherits from O1 O2, O2, O5 -- Because O2 inherits from O1 and O5 inherits from O3 O2, O4, O3 -- Because O2 inherits from O1 and O4 inherits from O2 O3, O2, O3 -- Because O3 inherits from O1 O3, O2, O5 -- Because O3 inherits from O1 and O5 inherits from O3 O3, O4, O3 -- Because O3 inherits from O1 and O4 inherits from O2 O3, O4, O5 -- Because O3 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 O4, O2, O3 -- Because O4 inherits from O1 O4, O2, O5 -- Because O4 inherits from O1 and O5 inherits from O3 O4, O4, O3 -- Because O4 inherits from O1 and O4 inherits from O2 O5, O2, O3 -- Because O5 inherits from O1 O5, O2, O5 -- Because O5 inherits from O1 and O5 inherits from O3 O5, O4, O3 -- Because O5 inherits from O1 and O4 inherits from O2 O5, O4, O5 -- Because O5 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 Note that the triple (O2, O4, O5) is absent from this list. This is because property P1 is defined explicitly for the triple (O2, O4, O5) and this prevents that triple from inheriting that property from (O1, O2, O3). Also note that the triple (O4, O4, O5) is also absent. This is because that triple inherits its value of P1="098" from (O2, O4, O5), because it is a closer parent than (O1, O2, O3). The straightforward way to do it is the following. First, for every triple that a property is defined on, select all possible child triples: select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value from TriplesAndProperties tp -- Select corresponding objects of the triple inner join Objects as Objects1 on Objects1.Id = tp.O1 inner join Objects as Objects2 on Objects2.Id = tp.O2 inner join Objects as Objects3 on Objects3.Id = tp.O3 -- Then add all possible children of all those objects inner join Objects as Children1 on Objects1.Id [isparentof] Children1.Id inner join Objects as Children2 on Objects2.Id [isparentof] Children2.Id inner join Objects as Children3 on Objects3.Id [isparentof] Children3.Id But this is not the whole story: if some triple inherits the same property from several parents, this query will yield conflicting results. Therefore, second step is to select just one of those conflicting results: select * from ( select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value, row_number() over( partition by Children1.Id, Children2.Id, Children3.Id, tp.Property order by Objects1.[depthInTheTree] descending, Objects2.[depthInTheTree] descending, Objects3.[depthInTheTree] descending ) as InheritancePriority from ... (see above) ) where InheritancePriority = 1 The window function row_number() over( ... ) does the following: for every unique combination of objects triple and property, it sorts all values by the ancestral distance from the triple to the parents that the value is inherited from, and then I only select the very first of the resulting list of values. A similar effect can be achieved with a GROUP BY and ORDER BY statements, but I just find the window function semantically cleaner (the execution plans they yield are identical). The point is, I need to select the closest of contributing ancestors, and for that I need to group and then sort within the group. And finally, now I can simply filter the result set by Property and Value. This scheme works. Very reliably and predictably. It has proven to be very powerful for the business task it implements. The only trouble is, it is awfuly slow. One might point out the join of seven tables might be slowing things down, but that is actually not the bottleneck. According to the actual execution plan I'm getting from the SQL Management Studio (as well as SQL Profiler), the bottleneck is the sorting. The problem is, in order to satisfy my window function, the server has to sort by Children1.Id, Children2.Id, Children3.Id, tp.Property, Parents1.[depthInTheTree] descending, Parents2.[depthInTheTree] descending, Parents3.[depthInTheTree] descending, and there can be no indexes it can use, because the values come from a cross join of several tables. EDIT: Per Michael Buen's suggestion (thank you, Michael), I have posted the whole puzzle to sqlfiddle here. One can see in the execution plan that the Sort operation accounts for 32% of the whole query, and that is going to grow with the number of total rows, because all the other operations use indexes. Usually in such cases I would use an indexed view, but not in this case, because indexed views cannot contain self-joins, of which there are six. The only way that I can think of so far is to create six copies of the Objects table and then use them for the joins, thus enabling an indexed view. Did the time come that I shall be reduced to that kind of hacks? The despair sets in.

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• Numpy zero rank array indexing/broadcasting

  - by Lemming

  I'm trying to write a function that supports broadcasting and is fast at the same time. However, numpy's zero-rank arrays are causing trouble as usual. I couldn't find anything useful on google, or by searching here. So, I'm asking you. How should I implement broadcasting efficiently and handle zero-rank arrays at the same time? This whole post became larger than anticipated, sorry. Details: To clarify what I'm talking about I'll give a simple example: Say I want to implement a Heaviside step-function. I.e. a function that acts on the real axis, which is 0 on the negative side, 1 on the positive side, and from case to case either 0, 0.5, or 1 at the point 0. Implementation Masking The most efficient way I found so far is the following. It uses boolean arrays as masks to assign the correct values to the corresponding slots in the output vector. from numpy import * def step_mask(x, limit=+1): """Heaviside step-function. y = 0 if x < 0 y = 1 if x > 0 See below for x == 0. Arguments: x Evaluate the function at these points. limit Which limit at x == 0? limit > 0: y = 1 limit == 0: y = 0.5 limit < 0: y = 0 Return: The values corresponding to x. """ b = broadcast(x, limit) out = zeros(b.shape) out[x>0] = 1 mask = (limit > 0) & (x == 0) out[mask] = 1 mask = (limit == 0) & (x == 0) out[mask] = 0.5 mask = (limit < 0) & (x == 0) out[mask] = 0 return out List Comprehension The following-the-numpy-docs way is to use a list comprehension on the flat iterator of the broadcast object. However, list comprehensions become absolutely unreadable for such complicated functions. def step_comprehension(x, limit=+1): b = broadcast(x, limit) out = empty(b.shape) out.flat = [ ( 1 if x_ > 0 else ( 0 if x_ < 0 else ( 1 if l_ > 0 else ( 0.5 if l_ ==0 else ( 0 ))))) for x_, l_ in b ] return out For Loop And finally, the most naive way is a for loop. It's probably the most readable option. However, Python for-loops are anything but fast. And hence, a really bad idea in numerics. def step_for(x, limit=+1): b = broadcast(x, limit) out = empty(b.shape) for i, (x_, l_) in enumerate(b): if x_ > 0: out[i] = 1 elif x_ < 0: out[i] = 0 elif l_ > 0: out[i] = 1 elif l_ < 0: out[i] = 0 else: out[i] = 0.5 return out Test First of all a brief test to see if the output is correct. >>> x = array([-1, -0.1, 0, 0.1, 1]) >>> step_mask(x, +1) array([ 0., 0., 1., 1., 1.]) >>> step_mask(x, 0) array([ 0. , 0. , 0.5, 1. , 1. ]) >>> step_mask(x, -1) array([ 0., 0., 0., 1., 1.]) It is correct, and the other two functions give the same output. Performance How about efficiency? These are the timings: In [45]: xl = linspace(-2, 2, 500001) In [46]: %timeit step_mask(xl) 10 loops, best of 3: 19.5 ms per loop In [47]: %timeit step_comprehension(xl) 1 loops, best of 3: 1.17 s per loop In [48]: %timeit step_for(xl) 1 loops, best of 3: 1.15 s per loop The masked version performs best as expected. However, I'm surprised that the comprehension is on the same level as the for loop. Zero Rank Arrays But, 0-rank arrays pose a problem. Sometimes you want to use a function scalar input. And preferably not have to worry about wrapping all scalars in at least 1-D arrays. >>> step_mask(1) Traceback (most recent call last): File "<ipython-input-50-91c06aa4487b>", line 1, in <module> step_mask(1) File "script.py", line 22, in step_mask out[x>0] = 1 IndexError: 0-d arrays can't be indexed. >>> step_for(1) Traceback (most recent call last): File "<ipython-input-51-4e0de4fcb197>", line 1, in <module> step_for(1) File "script.py", line 55, in step_for out[i] = 1 IndexError: 0-d arrays can't be indexed. >>> step_comprehension(1) array(1.0) Only the list comprehension can handle 0-rank arrays. The other two versions would need special case handling for 0-rank arrays. Numpy gets a bit messy when you want to use the same code for arrays and scalars. However, I really like to have functions that work on as arbitrary input as possible. Who knows which parameters I'll want to iterate over at some point. Question: What is the best way to implement a function as the one above? Is there a way to avoid if scalar then like special cases? I'm not looking for a built-in Heaviside. It's just a simplified example. In my code the above pattern appears in many places to make parameter iteration as simple as possible without littering the client code with for loops or comprehensions. Furthermore, I'm aware of Cython, or weave & Co., or implementation directly in C. However, the performance of the masked version above is sufficient for the moment. And for the moment I would like to keep things as simple as possible.

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• How do I search the MediaStore for a specific directory instead of entire external storage?

  - by Nick Lopez

  In my app I have an option that allows users to browse for audio files on their phone to add to the app. I am having trouble however with creating a faster way of processing the query code. Currently it searches the entire external storage and causes the phone to prompt a force close/wait warning. I would like to take the code I have posted below and make it more efficient by either searching in a specific folder on the phone or by streamlining the process to make the file search quicker. I am not sure how to do this however. Thanks! public class BrowseActivity extends DashboardActivity implements OnClickListener, OnItemClickListener { private List<Sound> soundsInDevice = new ArrayList<Sound>(); private List<Sound> checkedList; private ListView browsedList; private BrowserSoundAdapter adapter; private long categoryId; private Category category; private String currentCategoryName; private String description; // private Category newCategory ; private Button doneButton; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.activity_browse); checkedList = new ArrayList<Sound>(); browsedList = (ListView) findViewById(android.R.id.list); doneButton = (Button) findViewById(R.id.doneButton); soundsInDevice = getMediaSounds(); if (soundsInDevice.size() > 0) { adapter = new BrowserSoundAdapter(this, R.id.browseSoundName, soundsInDevice); } else { Toast.makeText(getApplicationContext(), getString(R.string.no_sounds_available), Toast.LENGTH_SHORT) .show(); } browsedList.setAdapter(adapter); browsedList.setOnItemClickListener(this); doneButton.setOnClickListener(this); } private List<Sound> getMediaSounds() { List<Sound> mediaSoundList = new ArrayList<Sound>(); ContentResolver cr = getContentResolver(); String[] projection = {MediaStore.Audio.Media._ID, MediaStore.Audio.Media.DISPLAY_NAME, MediaStore.Audio.Media.TITLE, MediaStore.Audio.Media.DATA, MediaStore.Audio.Media.DURATION}; final Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Log.v("MediaStore.Audio.Media.EXTERNAL_CONTENT_URI", "" + uri); final Cursor cursor = cr.query(uri, projection, null, null, null); int n = cursor.getCount(); Log.v("count", "" + n); if (cursor.moveToFirst()) { do { String soundName = cursor .getString(cursor .getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME)); Log.v("soundName", "" + soundName); String title = cursor .getString(cursor .getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE)); Log.v("title", "" + title); String path = cursor.getString(cursor .getColumnIndexOrThrow(MediaStore.Audio.Media.DATA)); Log.v("path", "" + path); Sound browsedSound = new Sound(title, path, false, false, false, false, 0); Log.v("browsedSound", "" + browsedSound); mediaSoundList.add(browsedSound); Log.v("mediaSoundList", "" + mediaSoundList.toString()); } while (cursor.moveToNext()); } return mediaSoundList; } public class BrowserSoundAdapter extends ArrayAdapter<Sound> { public BrowserSoundAdapter(Context context, int textViewResourceId, List<Sound> objects) { super(context, textViewResourceId, objects); } @Override public View getView(final int position, View convertView, ViewGroup parent) { ViewHolder viewHolder; View view = convertView; LayoutInflater inflater = getLayoutInflater(); if (view == null) { view = inflater.inflate(R.layout.list_item_browse, null); viewHolder = new ViewHolder(); viewHolder.soundNameTextView = (TextView) view .findViewById(R.id.browseSoundName); viewHolder.pathTextView = (TextView) view .findViewById(R.id.browseSoundPath); viewHolder.checkToAddSound = (CheckBox) view .findViewById(R.id.browse_checkbox); view.setTag(viewHolder); } else { viewHolder = (ViewHolder) view.getTag(); } final Sound sound = soundsInDevice.get(position); if (sound.isCheckedState()) { viewHolder.checkToAddSound.setChecked(true); } else { viewHolder.checkToAddSound.setChecked(false); } viewHolder.soundNameTextView.setText(sound.getName()); viewHolder.pathTextView.setText(sound.getUri()); viewHolder.checkToAddSound .setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { CheckBox cb = (CheckBox) v .findViewById(R.id.browse_checkbox); boolean checked = cb.isChecked(); boolean newValue = checked; updateView(position, newValue); doneButtonStatus(checkedList.size()); } }); return view; } } // Adapter view holder class private class ViewHolder { private TextView soundNameTextView; private TextView pathTextView; private CheckBox checkToAddSound; } // done button On Click @Override public void onClick(View view) { boolean status = getIntent().getBooleanExtra("FromAddCat", false); Log.v("for add category","enters in if"); if(status){ Log.v("for add category","enters in if1"); currentCategoryName = getIntent().getStringExtra("categoryName"); description = getIntent().getStringExtra("description"); boolean existCategory = SQLiteHelper.getCategoryStatus(currentCategoryName); if (!existCategory) { category = new Category(currentCategoryName, description, false); category.insert(); category.update(); Log.v("for add category","enters in if2"); } }else{ categoryId = getIntent().getLongExtra("categoryId",-1); category = SQLiteHelper.getCategory(categoryId); } for (Sound checkedsound : checkedList) { checkedsound.setCheckedState(false); checkedsound.insert(); category.getSounds().add(checkedsound); final Intent intent = new Intent(this, CategoriesActivity.class); finish(); startActivity(intent); } } @Override public void onItemClick(AdapterView<?> arg0, View view, int position, long arg3) { boolean checked = true; boolean newValue = false; CheckBox cb = (CheckBox) view.findViewById(R.id.browse_checkbox); if (cb.isChecked()) { cb.setChecked(!checked); newValue = !checked; } else { cb.setChecked(checked); newValue = checked; } updateView(position, newValue); doneButtonStatus(checkedList.size()); } private void doneButtonStatus(int size) { if (size > 0) { doneButton.setEnabled(true); doneButton.setBackgroundResource(R.drawable.done_button_drawable); } else { doneButton.setEnabled(false); doneButton.setBackgroundResource(R.drawable.done_btn_disabled); } } private void updateView(int index, boolean newValue) { System.out.println(newValue); Sound sound = soundsInDevice.get(index); if (newValue == true) { checkedList.add(sound); sound.setCheckedState(newValue); } else { checkedList.remove(sound); sound.setCheckedState(newValue); } } }

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• Using the West Wind Web Toolkit to set up AJAX and REST Services

  - by Rick Strahl

  I frequently get questions about which option to use for creating AJAX and REST backends for ASP.NET applications. There are many solutions out there to do this actually, but when I have a choice - not surprisingly - I fall back to my own tools in the West Wind West Wind Web Toolkit. I've talked a bunch about the 'in-the-box' solutions in the past so for a change in this post I'll talk about the tools that I use in my own and customer applications to handle AJAX and REST based access to service resources using the West Wind West Wind Web Toolkit. Let me preface this by saying that I like things to be easy. Yes flexible is very important as well but not at the expense of over-complexity. The goal I've had with my tools is make it drop dead easy, with good performance while providing the core features that I'm after, which are: Easy AJAX/JSON Callbacks Ability to return any kind of non JSON content (string, stream, byte[], images) Ability to work with both XML and JSON interchangeably for input/output Access endpoints via POST data, RPC JSON calls, GET QueryString values or Routing interface Easy to use generic JavaScript client to make RPC calls (same syntax, just what you need) Ability to create clean URLS with Routing Ability to use standard ASP.NET HTTP Stack for HTTP semantics It's all about options! In this post I'll demonstrate most of these features (except XML) in a few simple and short samples which you can download. So let's take a look and see how you can build an AJAX callback solution with the West Wind Web Toolkit. Installing the Toolkit Assemblies The easiest and leanest way of using the Toolkit in your Web project is to grab it via NuGet: West Wind Web and AJAX Utilities (Westwind.Web) and drop it into the project by right clicking in your Project and choosing Manage NuGet Packages from anywhere in the Project.   When done you end up with your project looking like this: What just happened? Nuget added two assemblies - Westwind.Web and Westwind.Utilities and the client ww.jquery.js library. It also added a couple of references into web.config: The default namespaces so they can be accessed in pages/views and a ScriptCompressionModule that the toolkit optionally uses to compress script resources served from within the assembly (namely ww.jquery.js and optionally jquery.js). Creating a new Service The West Wind Web Toolkit supports several ways of creating and accessing AJAX services, but for this post I'll stick to the lower level approach that works from any plain HTML page or of course MVC, WebForms, WebPages. There's also a WebForms specific control that makes this even easier but I'll leave that for another post. So, to create a new standalone AJAX/REST service we can create a new HttpHandler in the new project either as a pure class based handler or as a generic .ASHX handler. Both work equally well, but generic handlers don't require any web.config configuration so I'll use that here. In the root of the project add a Generic Handler. I'm going to call this one StockService.ashx. Once the handler has been created, edit the code and remove all of the handler body code. Then change the base class to CallbackHandler and add methods that have a [CallbackMethod] attribute. Here's the modified base handler implementation now looks like with an added HelloWorld method: using System; using Westwind.Web; namespace WestWindWebAjax { /// <summary> /// Handler implements CallbackHandler to provide REST/AJAX services /// </summary> public class SampleService : CallbackHandler { [CallbackMethod] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } } } Notice that the class inherits from CallbackHandler and that the HelloWorld service method is marked up with [CallbackMethod]. We're done here. Services Urlbased Syntax Once you compile, the 'service' is live can respond to requests. All CallbackHandlers support input in GET and POST formats, and can return results as JSON or XML. To check our fancy HelloWorld method we can now access the service like this: http://localhost/WestWindWebAjax/StockService.ashx?Method=HelloWorld&name=Rick which produces a default JSON response - in this case a string (wrapped in quotes as it's JSON): (note by default JSON will be downloaded by most browsers not displayed - various options are available to view JSON right in the browser) If I want to return the same data as XML I can tack on a &format=xml at the end of the querystring which produces: <string>Hello Rick. Time is: 11/1/2011 12:11:13 PM</string> Cleaner URLs with Routing Syntax If you want cleaner URLs for each operation you can also configure custom routes on a per URL basis similar to the way that WCF REST does. To do this you need to add a new RouteHandler to your application's startup code in global.asax.cs one for each CallbackHandler based service you create: protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); } With this code in place you can now add RouteUrl properties to any of your service methods. For the HelloWorld method that doesn't make a ton of sense but here is what a routed clean URL might look like in definition: [CallbackMethod(RouteUrl="stocks/HelloWorld/{name}")] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } The same URL I previously used now becomes a bit shorter and more readable with: http://localhost/WestWindWebAjax/HelloWorld/Rick It's an easy way to create cleaner URLs and still get the same functionality. Calling the Service with $.getJSON() Since the result produced is JSON you can now easily consume this data using jQuery's getJSON method. First we need a couple of scripts - jquery.js and ww.jquery.js in the page: <!DOCTYPE html> <html> <head> <link href="Css/Westwind.css" rel="stylesheet" type="text/css" /> <script src="scripts/jquery.min.js" type="text/javascript"></script> <script src="scripts/ww.jquery.min.js" type="text/javascript"></script> </head> <body> Next let's add a small HelloWorld example form (what else) that has a single textbox to type a name, a button and a div tag to receive the result: <fieldset> <legend>Hello World</legend> Please enter a name: <input type="text" name="txtHello" id="txtHello" value="" /> <input type="button" id="btnSayHello" value="Say Hello (POST)" /> <input type="button" id="btnSayHelloGet" value="Say Hello (GET)" /> <div id="divHelloMessage" class="errordisplay" style="display:none;width: 450px;" > </div> </fieldset> Then to call the HelloWorld method a little jQuery is used to hook the document startup and the button click followed by the $.getJSON call to retrieve the data from the server. <script type="text/javascript"> $(document).ready(function () { $("#btnSayHelloGet").click(function () { $.getJSON("SampleService.ashx", { Method: "HelloWorld", name: $("#txtHello").val() }, function (result) { $("#divHelloMessage") .text(result) .fadeIn(1000); }); });</script> .getJSON() expects a full URL to the endpoint of our service, which is the ASHX file. We can either provide a full URL (SampleService.ashx?Method=HelloWorld&name=Rick) or we can just provide the base URL and an object that encodes the query string parameters for us using an object map that has a property that matches each parameter for the server method. We can also use the clean URL routing syntax, but using the object parameter encoding actually is safer as the parameters will get properly encoded by jQuery. The result returned is whatever the result on the server method is - in this case a string. The string is applied to the divHelloMessage element and we're done. Obviously this is a trivial example, but it demonstrates the basics of getting a JSON response back to the browser. AJAX Post Syntax - using ajaxCallMethod() The previous example allows you basic control over the data that you send to the server via querystring parameters. This works OK for simple values like short strings, numbers and boolean values, but doesn't really work if you need to pass something more complex like an object or an array back up to the server. To handle traditional RPC type messaging where the idea is to map server side functions and results to a client side invokation, POST operations can be used. The easiest way to use this functionality is to use ww.jquery.js and the ajaxCallMethod() function. ww.jquery wraps jQuery's AJAX functions and knows implicitly how to call a CallbackServer method with parameters and parse the result. Let's look at another simple example that posts a simple value but returns something more interesting. Let's start with the service method: [CallbackMethod(RouteUrl="stocks/{symbol}")] public StockQuote GetStockQuote(string symbol) { Response.Cache.SetExpires(DateTime.UtcNow.Add(new TimeSpan(0, 2, 0))); StockServer server = new StockServer(); var quote = server.GetStockQuote(symbol); if (quote == null) throw new ApplicationException("Invalid Symbol passed."); return quote; } This sample utilizes a small StockServer helper class (included in the sample) that downloads a stock quote from Yahoo's financial site via plain HTTP GET requests and formats it into a StockQuote object. Lets create a small HTML block that lets us query for the quote and display it: <fieldset> <legend>Single Stock Quote</legend> Please enter a stock symbol: <input type="text" name="txtSymbol" id="txtSymbol" value="msft" /> <input type="button" id="btnStockQuote" value="Get Quote" /> <div id="divStockDisplay" class="errordisplay" style="display:none; width: 450px;"> <div class="label-left">Company:</div> <div id="stockCompany"></div> <div class="label-left">Last Price:</div> <div id="stockLastPrice"></div> <div class="label-left">Quote Time:</div> <div id="stockQuoteTime"></div> </div> </fieldset> The final result looks something like this:   Let's hook up the button handler to fire the request and fill in the data as shown: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").show().fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, HH:mm EST")); }, onPageError); }); So we point at SampleService.ashx and the GetStockQuote method, passing a single parameter of the input symbol value. Then there are two handlers for success and failure callbacks.  The success handler is the interesting part - it receives the stock quote as a result and assigns its values to various 'holes' in the stock display elements. The data that comes back over the wire is JSON and it looks like this: { "Symbol":"MSFT", "Company":"Microsoft Corpora", "OpenPrice":26.11, "LastPrice":26.01, "NetChange":0.02, "LastQuoteTime":"2011-11-03T02:00:00Z", "LastQuoteTimeString":"Nov. 11, 2011 4:20pm" } which is an object representation of the data. JavaScript can evaluate this JSON string back into an object easily and that's the reslut that gets passed to the success function. The quote data is then applied to existing page content by manually selecting items and applying them. There are other ways to do this more elegantly like using templates, but here we're only interested in seeing how the data is returned. The data in the object is typed - LastPrice is a number and QuoteTime is a date. Note about the date value: JavaScript doesn't have a date literal although the JSON embedded ISO string format used above  ("2011-11-03T02:00:00Z") is becoming fairly standard for JSON serializers. However, JSON parsers don't deserialize dates by default and return them by string. This is why the StockQuote actually returns a string value of LastQuoteTimeString for the same date. ajaxMethodCallback always converts dates properly into 'real' dates and the example above uses the real date value along with a .formatDate() data extension (also in ww.jquery.js) to display the raw date properly. Errors and Exceptions So what happens if your code fails? For example if I pass an invalid stock symbol to the GetStockQuote() method you notice that the code does this: if (quote == null) throw new ApplicationException("Invalid Symbol passed."); CallbackHandler automatically pushes the exception message back to the client so it's easy to pick up the error message. Regardless of what kind of error occurs: Server side, client side, protocol errors - any error will fire the failure handler with an error object parameter. The error is returned to the client via a JSON response in the error callback. In the previous examples I called onPageError which is a generic routine in ww.jquery that displays a status message on the bottom of the screen. But of course you can also take over the error handling yourself: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); }, function (error, xhr) { $("#divErrorDisplay").text(error.message).fadeIn(1000); }); }); The error object has a isCallbackError, message and  stackTrace properties, the latter of which is only populated when running in Debug mode, and this object is returned for all errors: Client side, transport and server side errors. Regardless of which type of error you get the same object passed (as well as the XHR instance optionally) which makes for a consistent error retrieval mechanism. Specifying HttpVerbs You can also specify HTTP Verbs that are allowed using the AllowedHttpVerbs option on the CallbackMethod attribute: [CallbackMethod(AllowedHttpVerbs=HttpVerbs.GET | HttpVerbs.POST)] public string HelloWorld(string name) { … } If you're building REST style API's this might be useful to force certain request semantics onto the client calling. For the above if call with a non-allowed HttpVerb the request returns a 405 error response along with a JSON (or XML) error object result. The default behavior is to allow all verbs access (HttpVerbs.All). Passing in object Parameters Up to now the parameters I passed were very simple. But what if you need to send something more complex like an object or an array? Let's look at another example now that passes an object from the client to the server. Keeping with the Stock theme here lets add a method called BuyOrder that lets us buy some shares for a stock. Consider the following service method that receives an StockBuyOrder object as a parameter: [CallbackMethod] public string BuyStock(StockBuyOrder buyOrder) { var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } public class StockBuyOrder { public string Symbol { get; set; } public int Quantity { get; set; } public DateTime BuyOn { get; set; } public StockBuyOrder() { BuyOn = DateTime.Now; } } This is a contrived do-nothing example that simply echoes back what was passed in, but it demonstrates how you can pass complex data to a callback method. On the client side we now have a very simple form that captures the three values on a form: <fieldset> <legend>Post a Stock Buy Order</legend> Enter a symbol: <input type="text" name="txtBuySymbol" id="txtBuySymbol" value="GLD" />&nbsp;&nbsp; Qty: <input type="text" name="txtBuyQty" id="txtBuyQty" value="10" style="width: 50px" />&nbsp;&nbsp; Buy on: <input type="text" name="txtBuyOn" id="txtBuyOn" value="<%= DateTime.Now.ToString("d") %>" style="width: 70px;" /> <input type="button" id="btnBuyStock" value="Buy Stock" /> <div id="divStockBuyMessage" class="errordisplay" style="display:none"></div> </fieldset> The completed form and demo then looks something like this:   The client side code that picks up the input values and assigns them to object properties and sends the AJAX request looks like this: $("#btnBuyStock").click(function () { // create an object map that matches StockBuyOrder signature var buyOrder = { Symbol: $("#txtBuySymbol").val(), Quantity: $("#txtBuyQty").val() * 1, // number Entered: new Date() } ajaxCallMethod("SampleService.ashx", "BuyStock", [buyOrder], function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError); }); The code creates an object and attaches the properties that match the server side object passed to the BuyStock method. Each property that you want to update needs to be included and the type must match (ie. string, number, date in this case). Any missing properties will not be set but also not cause any errors. Pass POST data instead of Objects In the last example I collected a bunch of values from form variables and stuffed them into object variables in JavaScript code. While that works, often times this isn't really helping - I end up converting my types on the client and then doing another conversion on the server. If lots of input controls are on a page and you just want to pick up the values on the server via plain POST variables - that can be done too - and it makes sense especially if you're creating and filling the client side object only to push data to the server. Let's add another method to the server that once again lets us buy a stock. But this time let's not accept a parameter but rather send POST data to the server. Here's the server method receiving POST data: [CallbackMethod] public string BuyStockPost() { StockBuyOrder buyOrder = new StockBuyOrder(); buyOrder.Symbol = Request.Form["txtBuySymbol"]; ; int qty; int.TryParse(Request.Form["txtBuyQuantity"], out qty); buyOrder.Quantity = qty; DateTime time; DateTime.TryParse(Request.Form["txtBuyBuyOn"], out time); buyOrder.BuyOn = time; // Or easier way yet //FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } Clearly we've made this server method take more code than it did with the object parameter. We've basically moved the parameter assignment logic from the client to the server. As a result the client code to call this method is now a bit shorter since there's no client side shuffling of values from the controls to an object. $("#btnBuyStockPost").click(function () { ajaxCallMethod("SampleService.ashx", "BuyStockPost", [], // Note: No parameters - function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError, // Force all page Form Variables to be posted { postbackMode: "Post" }); }); The client simply calls the BuyStockQuote method and pushes all the form variables from the page up to the server which parses them instead. The feature that makes this work is one of the options you can pass to the ajaxCallMethod() function: { postbackMode: "Post" }); which directs the function to include form variable POST data when making the service call. Other options include PostNoViewState (for WebForms to strip out WebForms crap vars), PostParametersOnly (default), None. If you pass parameters those are always posted to the server except when None is set. The above code can be simplified a bit by using the FormVariableBinder helper, which can unbind form variables directly into an object: FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); which replaces the manual Request.Form[] reading code. It receives the object to unbind into, a string of properties to skip, and an optional prefix which is stripped off form variables to match property names. The component is similar to the MVC model binder but it's independent of MVC. Returning non-JSON Data CallbackHandler also supports returning non-JSON/XML data via special return types. You can return raw non-JSON encoded strings like this: [CallbackMethod(ReturnAsRawString=true,ContentType="text/plain")] public string HelloWorldNoJSON(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } Calling this method results in just a plain string - no JSON encoding with quotes around the result. This can be useful if your server handling code needs to return a string or HTML result that doesn't fit well for a page or other UI component. Any string output can be returned. You can also return binary data. Stream, byte[] and Bitmap/Image results are automatically streamed back to the client. Notice that you should set the ContentType of the request either on the CallbackMethod attribute or using Response.ContentType. This ensures the Web Server knows how to display your binary response. Using a stream response makes it possible to return any of data. Streamed data can be pretty handy to return bitmap data from a method. The following is a method that returns a stock history graph for a particular stock over a provided number of years: [CallbackMethod(ContentType="image/png",RouteUrl="stocks/history/graph/{symbol}/{years}")] public Stream GetStockHistoryGraph(string symbol, int years = 2,int width = 500, int height=350) { if (width == 0) width = 500; if (height == 0) height = 350; StockServer server = new StockServer(); return server.GetStockHistoryGraph(symbol,"Stock History for " + symbol,width,height,years); } I can now hook this up into the JavaScript code when I get a stock quote. At the end of the process I can assign the URL to the service that returns the image into the src property and so force the image to display. Here's the changed code: $("#btnStockQuote").click(function () { var symbol = $("#txtSymbol").val(); ajaxCallMethod("SampleService.ashx", "GetStockQuote", [symbol], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); // display a stock chart $("#imgStockHistory").attr("src", "stocks/history/graph/" + symbol + "/2"); },onPageError); }); The resulting output then looks like this: The charting code uses the new ASP.NET 4.0 Chart components via code to display a bar chart of the 2 year stock data as part of the StockServer class which you can find in the sample download. The ability to return arbitrary data from a service is useful as you can see - in this case the chart is clearly associated with the service and it's nice that the graph generation can happen off a handler rather than through a page. Images are common resources, but output can also be PDF reports, zip files for downloads etc. which is becoming increasingly more common to be returned from REST endpoints and other applications. Why reinvent? Obviously the examples I've shown here are pretty basic in terms of functionality. But I hope they demonstrate the core features of AJAX callbacks that you need to work through in most applications which is simple: return data, send back data and potentially retrieve data in various formats. While there are other solutions when it comes down to making AJAX callbacks and servicing REST like requests, I like the flexibility my home grown solution provides. Simply put it's still the easiest solution that I've found that addresses my common use cases: AJAX JSON RPC style callbacks Url based access XML and JSON Output from single method endpoint XML and JSON POST support, querystring input, routing parameter mapping UrlEncoded POST data support on callbacks Ability to return stream/raw string data Essentially ability to return ANYTHING from Service and pass anything All these features are available in various solutions but not together in one place. I've been using this code base for over 4 years now in a number of projects both for myself and commercial work and it's served me extremely well. Besides the AJAX functionality CallbackHandler provides, it's also an easy way to create any kind of output endpoint I need to create. Need to create a few simple routines that spit back some data, but don't want to create a Page or View or full blown handler for it? Create a CallbackHandler and add a method or multiple methods and you have your generic endpoints.  It's a quick and easy way to add small code pieces that are pretty efficient as they're running through a pretty small handler implementation. I can have this up and running in a couple of minutes literally without any setup and returning just about any kind of data. Resources Download the Sample NuGet: Westwind Web and AJAX Utilities (Westwind.Web) ajaxCallMethod() Documentation Using the AjaxMethodCallback WebForms Control West Wind Web Toolkit Home Page West Wind Web Toolkit Source Code © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  jQuery  AJAX   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Capturing and Transforming ASP.NET Output with Response.Filter

  - by Rick Strahl

  During one of my Handlers and Modules session at DevConnections this week one of the attendees asked a question that I didn’t have an immediate answer for. Basically he wanted to capture response output completely and then apply some filtering to the output – effectively injecting some additional content into the page AFTER the page had completely rendered. Specifically the output should be captured from anywhere – not just a page and have this code injected into the page. Some time ago I posted some code that allows you to capture ASP.NET Page output by overriding the Render() method, capturing the HtmlTextWriter() and reading its content, modifying the rendered data as text then writing it back out. I’ve actually used this approach on a few occasions and it works fine for ASP.NET pages. But this obviously won’t work outside of the Page class environment and it’s not really generic – you have to create a custom page class in order to handle the output capture. [updated 11/16/2009 – updated ResponseFilterStream implementation and a few additional notes based on comments] Enter Response.Filter However, ASP.NET includes a Response.Filter which can be used – well to filter output. Basically Response.Filter is a stream through which the OutputStream is piped back to the Web Server (indirectly). As content is written into the Response object, the filter stream receives the appropriate Stream commands like Write, Flush and Close as well as read operations although for a Response.Filter that’s uncommon to be hit. The Response.Filter can be programmatically replaced at runtime which allows you to effectively intercept all output generation that runs through ASP.NET. A common Example: Dynamic GZip Encoding A rather common use of Response.Filter hooking up code based, dynamic  GZip compression for requests which is dead simple by applying a GZipStream (or DeflateStream) to Response.Filter. The following generic routines can be used very easily to detect GZip capability of the client and compress response output with a single line of code and a couple of library helper routines: WebUtils.GZipEncodePage(); which is handled with a few lines of reusable code and a couple of static helper methods: /// <summary> ///Sets up the current page or handler to use GZip through a Response.Filter ///IMPORTANT:  ///You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() {     HttpResponse Response = HttpContext.Current.Response;     if(IsGZipSupported())     {         stringAcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"];         if(AcceptEncoding.Contains("deflate"))         {             Response.Filter = newSystem.IO.Compression.DeflateStream(Response.Filter,                                        System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "deflate");         }         else        {             Response.Filter = newSystem.IO.Compression.GZipStream(Response.Filter,                                       System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "gzip");                            }     }     // Allow proxy servers to cache encoded and unencoded versions separately    Response.AppendHeader("Vary", "Content-Encoding"); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } GZipStream and DeflateStream are streams that are assigned to Response.Filter and by doing so apply the appropriate compression on the active Response. Response.Filter content is chunked So to implement a Response.Filter effectively requires only that you implement a custom stream and handle the Write() method to capture Response output as it’s written. At first blush this seems very simple – you capture the output in Write, transform it and write out the transformed content in one pass. And that indeed works for small amounts of content. But you see, the problem is that output is written in small buffer chunks (a little less than 16k it appears) rather than just a single Write() statement into the stream, which makes perfect sense for ASP.NET to stream data back to IIS in smaller chunks to minimize memory usage en route. Unfortunately this also makes it a more difficult to implement any filtering routines since you don’t directly get access to all of the response content which is problematic especially if those filtering routines require you to look at the ENTIRE response in order to transform or capture the output as is needed for the solution the gentleman in my session asked for. So in order to address this a slightly different approach is required that basically captures all the Write() buffers passed into a cached stream and then making the stream available only when it’s complete and ready to be flushed. As I was thinking about the implementation I also started thinking about the few instances when I’ve used Response.Filter implementations. Each time I had to create a new Stream subclass and create my custom functionality but in the end each implementation did the same thing – capturing output and transforming it. I thought there should be an easier way to do this by creating a re-usable Stream class that can handle stream transformations that are common to Response.Filter implementations. Creating a semi-generic Response Filter Stream Class What I ended up with is a ResponseFilterStream class that provides a handful of Events that allow you to capture and/or transform Response content. The class implements a subclass of Stream and then overrides Write() and Flush() to handle capturing and transformation operations. By exposing events it’s easy to hook up capture or transformation operations via single focused methods. ResponseFilterStream exposes the following events: CaptureStream, CaptureString Captures the output only and provides either a MemoryStream or String with the final page output. Capture is hooked to the Flush() operation of the stream. TransformStream, TransformString Allows you to transform the complete response output with events that receive a MemoryStream or String respectively and can you modify the output then return it back as a return value. The transformed output is then written back out in a single chunk to the response output stream. These events capture all output internally first then write the entire buffer into the response. TransformWrite, TransformWriteString Allows you to transform the Response data as it is written in its original chunk size in the Stream’s Write() method. Unlike TransformStream/TransformString which operate on the complete output, these events only see the current chunk of data written. This is more efficient as there’s no caching involved, but can cause problems due to searched content splitting over multiple chunks. Using this implementation, creating a custom Response.Filter transformation becomes as simple as the following code. To hook up the Response.Filter using the MemoryStream version event: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformStream += filter_TransformStream; Response.Filter = filter; and the event handler to do the transformation: MemoryStream filter_TransformStream(MemoryStream ms) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = encoding.GetString(ms.ToArray()); output = FixPaths(output); ms = new MemoryStream(output.Length); byte[] buffer = encoding.GetBytes(output); ms.Write(buffer,0,buffer.Length); return ms; } private string FixPaths(string output) { string path = HttpContext.Current.Request.ApplicationPath; // override root path wonkiness if (path == "/") path = ""; output = output.Replace("\"~/", "\"" + path + "/").Replace("'~/", "'" + path + "/"); return output; } The idea of the event handler is that you can do whatever you want to the stream and return back a stream – either the same one that’s been modified or a brand new one – which is then sent back to as the final response. The above code can be simplified even more by using the string version events which handle the stream to string conversions for you: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; and the event handler to do the transformation calling the same FixPaths method shown above: string filter_TransformString(string output) { return FixPaths(output); } The events for capturing output and capturing and transforming chunks work in a very similar way. By using events to handle the transformations ResponseFilterStream becomes a reusable component and we don’t have to create a new stream class or subclass an existing Stream based classed. By the way, the example used here is kind of a cool trick which transforms “~/” expressions inside of the final generated HTML output – even in plain HTML controls not HTML controls – and transforms them into the appropriate application relative path in the same way that ResolveUrl would do. So you can write plain old HTML like this: <a href=”~/default.aspx”>Home</a>  and have it turned into: <a href=”/myVirtual/default.aspx”>Home</a>  without having to use an ASP.NET control like Hyperlink or Image or having to constantly use: <img src=”<%= ResolveUrl(“~/images/home.gif”) %>” /> in MVC applications (which frankly is one of the most annoying things about MVC especially given the path hell that extension-less and endpoint-less URLs impose). I can’t take credit for this idea. While discussing the Response.Filter issues on Twitter a hint from Dylan Beattie who pointed me at one of his examples which does something similar. I thought the idea was cool enough to use an example for future demos of Response.Filter functionality in ASP.NET next I time I do the Modules and Handlers talk (which was great fun BTW). How practical this is is debatable however since there’s definitely some overhead to using a Response.Filter in general and especially on one that caches the output and the re-writes it later. Make sure to test for performance anytime you use Response.Filter hookup and make sure it' doesn’t end up killing perf on you. You’ve been warned :-}. How does ResponseFilterStream work? The big win of this implementation IMHO is that it’s a reusable  component – so for implementation there’s no new class, no subclassing – you simply attach to an event to implement an event handler method with a straight forward signature to retrieve the stream or string you’re interested in. The implementation is based on a subclass of Stream as is required in order to handle the Response.Filter requirements. What’s different than other implementations I’ve seen in various places is that it supports capturing output as a whole to allow retrieving the full response output for capture or modification. The exception are the TransformWrite and TransformWrite events which operate only active chunk of data written by the Response. For captured output, the Write() method captures output into an internal MemoryStream that is cached until writing is complete. So Write() is called when ASP.NET writes to the Response stream, but the filter doesn’t pass on the Write immediately to the filter’s internal stream. The data is cached and only when the Flush() method is called to finalize the Stream’s output do we actually send the cached stream off for transformation (if the events are hooked up) and THEN finally write out the returned content in one big chunk. Here’s the implementation of ResponseFilterStream: /// <summary> /// A semi-generic Stream implementation for Response.Filter with /// an event interface for handling Content transformations via /// Stream or String. /// <remarks> /// Use with care for large output as this implementation copies /// the output into a memory stream and so increases memory usage. /// </remarks> /// </summary> public class ResponseFilterStream : Stream { /// <summary> /// The original stream /// </summary> Stream _stream; /// <summary> /// Current position in the original stream /// </summary> long _position; /// <summary> /// Stream that original content is read into /// and then passed to TransformStream function /// </summary> MemoryStream _cacheStream = new MemoryStream(5000); /// <summary> /// Internal pointer that that keeps track of the size /// of the cacheStream /// </summary> int _cachePointer = 0; /// <summary> /// /// </summary> /// <param name="responseStream"></param> public ResponseFilterStream(Stream responseStream) { _stream = responseStream; } /// <summary> /// Determines whether the stream is captured /// </summary> private bool IsCaptured { get { if (CaptureStream != null || CaptureString != null || TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Determines whether the Write method is outputting data immediately /// or delaying output until Flush() is fired. /// </summary> private bool IsOutputDelayed { get { if (TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Event that captures Response output and makes it available /// as a MemoryStream instance. Output is captured but won't /// affect Response output. /// </summary> public event Action<MemoryStream> CaptureStream; /// <summary> /// Event that captures Response output and makes it available /// as a string. Output is captured but won't affect Response output. /// </summary> public event Action<string> CaptureString; /// <summary> /// Event that allows you transform the stream as each chunk of /// the output is written in the Write() operation of the stream. /// This means that that it's possible/likely that the input /// buffer will not contain the full response output but only /// one of potentially many chunks. /// /// This event is called as part of the filter stream's Write() /// operation. /// </summary> public event Func<byte[], byte[]> TransformWrite; /// <summary> /// Event that allows you to transform the response stream as /// each chunk of bytep[] output is written during the stream's write /// operation. This means it's possibly/likely that the string /// passed to the handler only contains a portion of the full /// output. Typical buffer chunks are around 16k a piece. /// /// This event is called as part of the stream's Write operation. /// </summary> public event Func<string, string> TransformWriteString; /// <summary> /// This event allows capturing and transformation of the entire /// output stream by caching all write operations and delaying final /// response output until Flush() is called on the stream. /// </summary> public event Func<MemoryStream, MemoryStream> TransformStream; /// <summary> /// Event that can be hooked up to handle Response.Filter /// Transformation. Passed a string that you can modify and /// return back as a return value. The modified content /// will become the final output. /// </summary> public event Func<string, string> TransformString; protected virtual void OnCaptureStream(MemoryStream ms) { if (CaptureStream != null) CaptureStream(ms); } private void OnCaptureStringInternal(MemoryStream ms) { if (CaptureString != null) { string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); OnCaptureString(content); } } protected virtual void OnCaptureString(string output) { if (CaptureString != null) CaptureString(output); } protected virtual byte[] OnTransformWrite(byte[] buffer) { if (TransformWrite != null) return TransformWrite(buffer); return buffer; } private byte[] OnTransformWriteStringInternal(byte[] buffer) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = OnTransformWriteString(encoding.GetString(buffer)); return encoding.GetBytes(output); } private string OnTransformWriteString(string value) { if (TransformWriteString != null) return TransformWriteString(value); return value; } protected virtual MemoryStream OnTransformCompleteStream(MemoryStream ms) { if (TransformStream != null) return TransformStream(ms); return ms; } /// <summary> /// Allows transforming of strings /// /// Note this handler is internal and not meant to be overridden /// as the TransformString Event has to be hooked up in order /// for this handler to even fire to avoid the overhead of string /// conversion on every pass through. /// </summary> /// <param name="responseText"></param> /// <returns></returns> private string OnTransformCompleteString(string responseText) { if (TransformString != null) TransformString(responseText); return responseText; } /// <summary> /// Wrapper method form OnTransformString that handles /// stream to string and vice versa conversions /// </summary> /// <param name="ms"></param> /// <returns></returns> internal MemoryStream OnTransformCompleteStringInternal(MemoryStream ms) { if (TransformString == null) return ms; //string content = ms.GetAsString(); string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); content = TransformString(content); byte[] buffer = HttpContext.Current.Response.ContentEncoding.GetBytes(content); ms = new MemoryStream(); ms.Write(buffer, 0, buffer.Length); //ms.WriteString(content); return ms; } /// <summary> /// /// </summary> public override bool CanRead { get { return true; } } public override bool CanSeek { get { return true; } } /// <summary> /// /// </summary> public override bool CanWrite { get { return true; } } /// <summary> /// /// </summary> public override long Length { get { return 0; } } /// <summary> /// /// </summary> public override long Position { get { return _position; } set { _position = value; } } /// <summary> /// /// </summary> /// <param name="offset"></param> /// <param name="direction"></param> /// <returns></returns> public override long Seek(long offset, System.IO.SeekOrigin direction) { return _stream.Seek(offset, direction); } /// <summary> /// /// </summary> /// <param name="length"></param> public override void SetLength(long length) { _stream.SetLength(length); } /// <summary> /// /// </summary> public override void Close() { _stream.Close(); } /// <summary> /// Override flush by writing out the cached stream data /// </summary> public override void Flush() { if (IsCaptured && _cacheStream.Length > 0) { // Check for transform implementations _cacheStream = OnTransformCompleteStream(_cacheStream); _cacheStream = OnTransformCompleteStringInternal(_cacheStream); OnCaptureStream(_cacheStream); OnCaptureStringInternal(_cacheStream); // write the stream back out if output was delayed if (IsOutputDelayed) _stream.Write(_cacheStream.ToArray(), 0, (int)_cacheStream.Length); // Clear the cache once we've written it out _cacheStream.SetLength(0); } // default flush behavior _stream.Flush(); } /// <summary> /// /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> /// <returns></returns> public override int Read(byte[] buffer, int offset, int count) { return _stream.Read(buffer, offset, count); } /// <summary> /// Overriden to capture output written by ASP.NET and captured /// into a cached stream that is written out later when Flush() /// is called. /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> public override void Write(byte[] buffer, int offset, int count) { if ( IsCaptured ) { // copy to holding buffer only - we'll write out later _cacheStream.Write(buffer, 0, count); _cachePointer += count; } // just transform this buffer if (TransformWrite != null) buffer = OnTransformWrite(buffer); if (TransformWriteString != null) buffer = OnTransformWriteStringInternal(buffer); if (!IsOutputDelayed) _stream.Write(buffer, offset, buffer.Length); } } The key features are the events and corresponding OnXXX methods that handle the event hookups, and the Write() and Flush() methods of the stream implementation. All the rest of the members tend to be plain jane passthrough stream implementation code without much consequence. I do love the way Action<t> and Func<T> make it so easy to create the event signatures for the various events – sweet. A few Things to consider Performance Response.Filter is not great for performance in general as it adds another layer of indirection to the ASP.NET output pipeline, and this implementation in particular adds a memory hit as it basically duplicates the response output into the cached memory stream which is necessary since you may have to look at the entire response. If you have large pages in particular this can cause potentially serious memory pressure in your server application. So be careful of wholesale adoption of this (or other) Response.Filters. Make sure to do some performance testing to ensure it’s not killing your app’s performance. Response.Filter works everywhere A few questions came up in comments and discussion as to capturing ALL output hitting the site and – yes you can definitely do that by assigning a Response.Filter inside of a module. If you do this however you’ll want to be very careful and decide which content you actually want to capture especially in IIS 7 which passes ALL content – including static images/CSS etc. through the ASP.NET pipeline. So it is important to filter only on what you’re looking for – like the page extension or maybe more effectively the Response.ContentType. Response.Filter Chaining Originally I thought that filter chaining doesn’t work at all due to a bug in the stream implementation code. But it’s quite possible to assign multiple filters to the Response.Filter property. So the following actually works to both compress the output and apply the transformed content: WebUtils.GZipEncodePage(); ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; However the following does not work resulting in invalid content encoding errors: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; WebUtils.GZipEncodePage(); In other words multiple Response filters can work together but it depends entirely on the implementation whether they can be chained or in which order they can be chained. In this case running the GZip/Deflate stream filters apparently relies on the original content length of the output and chokes when the content is modified. But if attaching the compression first it works fine as unintuitive as that may seem. Resources Download example code Capture Output from ASP.NET Pages © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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• Replacing instructions in a method's MethodBody

  - by Alix

  Hi, (First of all, this is a very lengthy post, but don't worry: I've already implemented all of it, I'm just asking your opinion.) I'm having trouble implementing the following; I'd appreciate some help: I get a Type as parameter. I define a subclass using reflection. Notice that I don't intend to modify the original type, but create a new one. I create a property per field of the original class, like so: public class OriginalClass { private int x; } public class Subclass : OriginalClass { private int x; public int X { get { return x; } set { x = value; } } } For every method of the superclass, I create an analogous method in the subclass. The method's body must be the same except that I replace the instructions ldfld x with callvirt this.get_X, that is, instead of reading from the field directly I call the get accessor. I'm having trouble with step 4. I know you're not supposed to manipulate code like this, but I really need to. Here's what I've tried: Attempt #1: Use Mono.Cecil. This would allow me to parse the body of the method into human-readable Instructions, and easily replace instructions. However, the original type isn't in a .dll file, so I can't find a way to load it with Mono.Cecil. Writing the type to a .dll, then load it, then modify it and write the new type to disk (which I think is the way you create a type with Mono.Cecil), and then load it seems like a huge overhead. Attempt #2: Use Mono.Reflection. This would also allow me to parse the body into Instructions, but then I have no support for replacing instructions. I've implemented a very ugly and inefficient solution using Mono.Reflection, but it doesn't yet support methods that contain try-catch statements (although I guess I can implement this) and I'm concerned that there may be other scenarios in which it won't work, since I'm using the ILGenerator in a somewhat unusual way. Also, it's very ugly ;). Here's what I've done: private void TransformMethod(MethodInfo methodInfo) { // Create a method with the same signature. ParameterInfo[] paramList = methodInfo.GetParameters(); Type[] args = new Type[paramList.Length]; for (int i = 0; i < args.Length; i++) { args[i] = paramList[i].ParameterType; } MethodBuilder methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, methodInfo.Attributes, methodInfo.ReturnType, args); ILGenerator ilGen = methodBuilder.GetILGenerator(); // Declare the same local variables as in the original method. IList<LocalVariableInfo> locals = methodInfo.GetMethodBody().LocalVariables; foreach (LocalVariableInfo local in locals) { ilGen.DeclareLocal(local.LocalType); } // Get readable instructions. IList<Instruction> instructions = methodInfo.GetInstructions(); // I first need to define labels for every instruction in case I // later find a jump to that instruction. Once the instruction has // been emitted I cannot label it, so I'll need to do it in advance. // Since I'm doing a first pass on the method's body anyway, I could // instead just create labels where they are truly needed, but for // now I'm using this quick fix. Dictionary<int, Label> labels = new Dictionary<int, Label>(); foreach (Instruction instr in instructions) { labels[instr.Offset] = ilGen.DefineLabel(); } foreach (Instruction instr in instructions) { // Mark this instruction with a label, in case there's a branch // instruction that jumps here. ilGen.MarkLabel(labels[instr.Offset]); // If this is the instruction that I want to replace (ldfld x)... if (instr.OpCode == OpCodes.Ldfld) { // ...get the get accessor for the accessed field (get_X()) // (I have the accessors in a dictionary; this isn't relevant), MethodInfo safeReadAccessor = dataMembersSafeAccessors[((FieldInfo) instr.Operand).Name][0]; // ...instead of emitting the original instruction (ldfld x), // emit a call to the get accessor, ilGen.Emit(OpCodes.Callvirt, safeReadAccessor); // Else (it's any other instruction), reemit the instruction, unaltered. } else { Reemit(instr, ilGen, labels); } } } And here comes the horrible, horrible Reemit method: private void Reemit(Instruction instr, ILGenerator ilGen, Dictionary<int, Label> labels) { // If the instruction doesn't have an operand, emit the opcode and return. if (instr.Operand == null) { ilGen.Emit(instr.OpCode); return; } // Else (it has an operand)... // If it's a branch instruction, retrieve the corresponding label (to // which we want to jump), emit the instruction and return. if (instr.OpCode.FlowControl == FlowControl.Branch) { ilGen.Emit(instr.OpCode, labels[Int32.Parse(instr.Operand.ToString())]); return; } // Otherwise, simply emit the instruction. I need to use the right // Emit call, so I need to cast the operand to its type. Type operandType = instr.Operand.GetType(); if (typeof(byte).IsAssignableFrom(operandType)) ilGen.Emit(instr.OpCode, (byte) instr.Operand); else if (typeof(double).IsAssignableFrom(operandType)) ilGen.Emit(instr.OpCode, (double) instr.Operand); else if (typeof(float).IsAssignableFrom(operandType)) ilGen.Emit(instr.OpCode, (float) instr.Operand); else if (typeof(int).IsAssignableFrom(operandType)) ilGen.Emit(instr.OpCode, (int) instr.Operand); ... // you get the idea. This is a pretty long method, all like this. } Branch instructions are a special case because instr.Operand is SByte, but Emit expects an operand of type Label. Hence the need for the Dictionary labels. As you can see, this is pretty horrible. What's more, it doesn't work in all cases, for instance with methods that contain try-catch statements, since I haven't emitted them using methods BeginExceptionBlock, BeginCatchBlock, etc, of ILGenerator. This is getting complicated. I guess I can do it: MethodBody has a list of ExceptionHandlingClause that should contain the necessary information to do this. But I don't like this solution anyway, so I'll save this as a last-resort solution. Attempt #3: Go bare-back and just copy the byte array returned by MethodBody.GetILAsByteArray(), since I only want to replace a single instruction for another single instruction of the same size that produces the exact same result: it loads the same type of object on the stack, etc. So there won't be any labels shifting and everything should work exactly the same. I've done this, replacing specific bytes of the array and then calling MethodBuilder.CreateMethodBody(byte[], int), but I still get the same error with exceptions, and I still need to declare the local variables or I'll get an error... even when I simply copy the method's body and don't change anything. So this is more efficient but I still have to take care of the exceptions, etc. Sigh. Here's the implementation of attempt #3, in case anyone is interested: private void TransformMethod(MethodInfo methodInfo, Dictionary<string, MethodInfo[]> dataMembersSafeAccessors, ModuleBuilder moduleBuilder) { ParameterInfo[] paramList = methodInfo.GetParameters(); Type[] args = new Type[paramList.Length]; for (int i = 0; i < args.Length; i++) { args[i] = paramList[i].ParameterType; } MethodBuilder methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, methodInfo.Attributes, methodInfo.ReturnType, args); ILGenerator ilGen = methodBuilder.GetILGenerator(); IList<LocalVariableInfo> locals = methodInfo.GetMethodBody().LocalVariables; foreach (LocalVariableInfo local in locals) { ilGen.DeclareLocal(local.LocalType); } byte[] rawInstructions = methodInfo.GetMethodBody().GetILAsByteArray(); IList<Instruction> instructions = methodInfo.GetInstructions(); int k = 0; foreach (Instruction instr in instructions) { if (instr.OpCode == OpCodes.Ldfld) { MethodInfo safeReadAccessor = dataMembersSafeAccessors[((FieldInfo) instr.Operand).Name][0]; // Copy the opcode: Callvirt. byte[] bytes = toByteArray(OpCodes.Callvirt.Value); for (int m = 0; m < OpCodes.Callvirt.Size; m++) { rawInstructions[k++] = bytes[put.Length - 1 - m]; } // Copy the operand: the accessor's metadata token. bytes = toByteArray(moduleBuilder.GetMethodToken(safeReadAccessor).Token); for (int m = instr.Size - OpCodes.Ldfld.Size - 1; m >= 0; m--) { rawInstructions[k++] = bytes[m]; } // Skip this instruction (do not replace it). } else { k += instr.Size; } } methodBuilder.CreateMethodBody(rawInstructions, rawInstructions.Length); } private static byte[] toByteArray(int intValue) { byte[] intBytes = BitConverter.GetBytes(intValue); if (BitConverter.IsLittleEndian) Array.Reverse(intBytes); return intBytes; } private static byte[] toByteArray(short shortValue) { byte[] intBytes = BitConverter.GetBytes(shortValue); if (BitConverter.IsLittleEndian) Array.Reverse(intBytes); return intBytes; } (I know it isn't pretty. Sorry. I put it quickly together to see if it would work.) I don't have much hope, but can anyone suggest anything better than this? Sorry about the extremely lengthy post, and thanks.

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• Parsing concatenated, non-delimited XML messages from TCP-stream using C#

  - by thaller

  I am trying to parse XML messages which are send to my C# application over TCP. Unfortunately, the protocol can not be changed and the XML messages are not delimited and no length prefix is used. Moreover the character encoding is not fixed but each message starts with an XML declaration <?xml>. The question is, how can i read one XML message at a time, using C#. Up to now, I tried to read the data from the TCP stream into a byte array and use it through a MemoryStream. The problem is, the buffer might contain more than one XML messages or the first message may be incomplete. In these cases, I get an exception when trying to parse it with XmlReader.Read or XmlDocument.Load, but unfortunately the XmlException does not really allow me to distinguish the problem (except parsing the localized error string). I tried using XmlReader.Read and count the number of Element and EndElement nodes. That way I know when I am finished reading the first, entire XML message. However, there are several problems. If the buffer does not yet contain the entire message, how can I distinguish the XmlException from an actually invalid, non-well-formed message? In other words, if an exception is thrown before reading the first root EndElement, how can I decide whether to abort the connection with error, or to collect more bytes from the TCP stream? If no exception occurs, the XmlReader is positioned at the start of the root EndElement. Casting the XmlReader to IXmlLineInfo gives me the current LineNumber and LinePosition, however it is not straight forward to get the byte position where the EndElement really ends. In order to do that, I would have to convert the byte array into a string (with the encoding specified in the XML declaration), seek to LineNumber,LinePosition and convert that back to the byte offset. I try to do that with StreamReader.ReadLine, but the stream reader gives no public access to the current byte position. All this seams very inelegant and non robust. I wonder if you have ideas for a better solution. Thank you. EDIT: I looked around and think that the situation is as follows (I might be wrong, corrections are welcome): I found no method so that the XmlReader can continue parsing a second XML message (at least not, if the second message has an XmlDeclaration). XmlTextReader.ResetState could do something similar, but for that I would have to assume the same encoding for all messages. Therefor I could not connect the XmlReader directly to the TcpStream. After closing the XmlReader, the buffer is not positioned at the readers last position. So it is not possible to close the reader and use a new one to continue with the next message. I guess the reason for this is, that the reader could not successfully seek on every possible input stream. When XmlReader throws an exception it can not be determined whether it happened because of an premature EOF or because of a non-wellformed XML. XmlReader.EOF is not set in case of an exception. As workaround I derived my own MemoryBuffer, which returns the very last byte as a single byte. This way I know that the XmlReader was really interested in the last byte and the following exception is likely due to a truncated message (this is kinda sloppy, in that it might not detect every non-wellformed message. However, after appending more bytes to the buffer, sooner or later the error will be detected. I could cast my XmlReader to the IXmlLineInfo interface, which gives access to the LineNumber and the LinePosition of the current node. So after reading the first message I remember these positions and use it to truncate the buffer. Here comes the really sloppy part, because I have to use the character encoding to get the byte position. I am sure you could find test cases for the code below where it breaks (e.g. internal elements with mixed encoding). But up to now it worked for all my tests. The parser class follows here -- may it be useful (I know, its very far from perfect...) class XmlParser { private byte[] buffer = new byte[0]; public int Length { get { return buffer.Length; } } // Append new binary data to the internal data buffer... public XmlParser Append(byte[] buffer2) { if (buffer2 != null && buffer2.Length > 0) { // I know, its not an efficient way to do this. // The EofMemoryStream should handle a List<byte[]> ... byte[] new_buffer = new byte[buffer.Length + buffer2.Length]; buffer.CopyTo(new_buffer, 0); buffer2.CopyTo(new_buffer, buffer.Length); buffer = new_buffer; } return this; } // MemoryStream which returns the last byte of the buffer individually, // so that we know that the buffering XmlReader really locked at the last // byte of the stream. // Moreover there is an EOF marker. private class EofMemoryStream: Stream { public bool EOF { get; private set; } private MemoryStream mem_; public override bool CanSeek { get { return false; } } public override bool CanWrite { get { return false; } } public override bool CanRead { get { return true; } } public override long Length { get { return mem_.Length; } } public override long Position { get { return mem_.Position; } set { throw new NotSupportedException(); } } public override void Flush() { mem_.Flush(); } public override long Seek(long offset, SeekOrigin origin) { throw new NotSupportedException(); } public override void SetLength(long value) { throw new NotSupportedException(); } public override void Write(byte[] buffer, int offset, int count) { throw new NotSupportedException(); } public override int Read(byte[] buffer, int offset, int count) { count = Math.Min(count, Math.Max(1, (int)(Length - Position - 1))); int nread = mem_.Read(buffer, offset, count); if (nread == 0) { EOF = true; } return nread; } public EofMemoryStream(byte[] buffer) { mem_ = new MemoryStream(buffer, false); EOF = false; } protected override void Dispose(bool disposing) { mem_.Dispose(); } } // Parses the first xml message from the stream. // If the first message is not yet complete, it returns null. // If the buffer contains non-wellformed xml, it ~should~ throw an exception. // After reading an xml message, it pops the data from the byte array. public Message deserialize() { if (buffer.Length == 0) { return null; } Message message = null; Encoding encoding = Message.default_encoding; //string xml = encoding.GetString(buffer); using (EofMemoryStream sbuffer = new EofMemoryStream (buffer)) { XmlDocument xmlDocument = null; XmlReaderSettings settings = new XmlReaderSettings(); int LineNumber = -1; int LinePosition = -1; bool truncate_buffer = false; using (XmlReader xmlReader = XmlReader.Create(sbuffer, settings)) { try { // Read to the first node (skipping over some element-types. // Don't use MoveToContent here, because it would skip the // XmlDeclaration too... while (xmlReader.Read() && (xmlReader.NodeType==XmlNodeType.Whitespace || xmlReader.NodeType==XmlNodeType.Comment)) { }; // Check for XML declaration. // If the message has an XmlDeclaration, extract the encoding. switch (xmlReader.NodeType) { case XmlNodeType.XmlDeclaration: while (xmlReader.MoveToNextAttribute()) { if (xmlReader.Name == "encoding") { encoding = Encoding.GetEncoding(xmlReader.Value); } } xmlReader.MoveToContent(); xmlReader.Read(); break; } // Move to the first element. xmlReader.MoveToContent(); // Read the entire document. xmlDocument = new XmlDocument(); xmlDocument.Load(xmlReader.ReadSubtree()); } catch (XmlException e) { // The parsing of the xml failed. If the XmlReader did // not yet look at the last byte, it is assumed that the // XML is invalid and the exception is re-thrown. if (sbuffer.EOF) { return null; } throw e; } { // Try to serialize an internal data structure using XmlSerializer. Type type = null; try { type = Type.GetType("my.namespace." + xmlDocument.DocumentElement.Name); } catch (Exception e) { // No specialized data container for this class found... } if (type == null) { message = new Message(); } else { // TODO: reuse the serializer... System.Xml.Serialization.XmlSerializer ser = new System.Xml.Serialization.XmlSerializer(type); message = (Message)ser.Deserialize(new XmlNodeReader(xmlDocument)); } message.doc = xmlDocument; } // At this point, the first XML message was sucessfully parsed. // Remember the lineposition of the current end element. IXmlLineInfo xmlLineInfo = xmlReader as IXmlLineInfo; if (xmlLineInfo != null && xmlLineInfo.HasLineInfo()) { LineNumber = xmlLineInfo.LineNumber; LinePosition = xmlLineInfo.LinePosition; } // Try to read the rest of the buffer. // If an exception is thrown, another xml message appears. // This way the xml parser could tell us that the message is finished here. // This would be prefered as truncating the buffer using the line info is sloppy. try { while (xmlReader.Read()) { } } catch { // There comes a second message. Needs workaround for trunkating. truncate_buffer = true; } } if (truncate_buffer) { if (LineNumber < 0) { throw new Exception("LineNumber not given. Cannot truncate xml buffer"); } // Convert the buffer to a string using the encoding found before // (or the default encoding). string s = encoding.GetString(buffer); // Seek to the line. int char_index = 0; while (--LineNumber > 0) { // Recognize \r , \n , \r\n as newlines... char_index = s.IndexOfAny(new char[] {'\r', '\n'}, char_index); // char_index should not be -1 because LineNumber>0, otherwise an RangeException is // thrown, which is appropriate. char_index++; if (s[char_index-1]=='\r' && s.Length>char_index && s[char_index]=='\n') { char_index++; } } char_index += LinePosition - 1; var rgx = new System.Text.RegularExpressions.Regex(xmlDocument.DocumentElement.Name + "[ \r\n\t]*\\>"); System.Text.RegularExpressions.Match match = rgx.Match(s, char_index); if (!match.Success || match.Index != char_index) { throw new Exception("could not find EndElement to truncate the xml buffer."); } char_index += match.Value.Length; // Convert the character offset back to the byte offset (for the given encoding). int line1_boffset = encoding.GetByteCount(s.Substring(0, char_index)); // remove the bytes from the buffer. buffer = buffer.Skip(line1_boffset).ToArray(); } else { buffer = new byte[0]; } } return message; } }

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• Query on simple C++ threadpool implementation

  - by ticketman

  Stackoverflow has been a tremendous help to me and I'd to give something back to the community. I have been implementing a simple threadpool using the tinythread C++ portable thread library, using what I have learnt from Stackoverflow. I am new to thread programming, so not that comfortable with mutexes, etc. I have a question best asked after presenting the code (which runs quite well under Linux): // ThreadPool.h class ThreadPool { public: ThreadPool(); ~ThreadPool(); // Creates a pool of threads and gets them ready to be used void CreateThreads(int numOfThreads); // Assigns a job to a thread in the pool, but doesn't start the job // Each SubmitJob call will use up one thread of the pool. // This operation can only be undone by calling StartJobs and // then waiting for the jobs to complete. On completion, // new jobs may be submitted. void SubmitJob( void (*workFunc)(void *), void *workData ); // Begins execution of all the jobs in the pool. void StartJobs(); // Waits until all jobs have completed. // The wait will block the caller. // On completion, new jobs may be submitted. void WaitForJobsToComplete(); private: enum typeOfWorkEnum { e_work, e_quit }; class ThreadData { public: bool ready; // thread has been created and is ready for work bool haveWorkToDo; typeOfWorkEnum typeOfWork; // Pointer to the work function each thread has to call. void (*workFunc)(void *); // Pointer to work data void *workData; ThreadData() : ready(false), haveWorkToDo(false) { }; }; struct ThreadArgStruct { ThreadPool *threadPoolInstance; int threadId; }; // Data for each thread ThreadData *m_ThreadData; ThreadPool(ThreadPool const&); // copy ctor hidden ThreadPool& operator=(ThreadPool const&); // assign op. hidden // Static function that provides the function pointer that a thread can call // By including the ThreadPool instance in the void * parameter, // we can use it to access other data and methods in the ThreadPool instance. static void ThreadFuncWrapper(void *arg) { ThreadArgStruct *threadArg = static_cast<ThreadArgStruct *>(arg); threadArg->threadPoolInstance->ThreadFunc(threadArg->threadId); } // The function each thread calls void ThreadFunc( int threadId ); // Called by the thread pool destructor void DestroyThreadPool(); // Total number of threads available // (fixed on creation of thread pool) int m_numOfThreads; int m_NumOfThreadsDoingWork; int m_NumOfThreadsGivenJobs; // List of threads std::vector<tthread::thread *> m_ThreadList; // Condition variable to signal each thread has been created and executing tthread::mutex m_ThreadReady_mutex; tthread::condition_variable m_ThreadReady_condvar; // Condition variable to signal each thread to start work tthread::mutex m_WorkToDo_mutex; tthread::condition_variable m_WorkToDo_condvar; // Condition variable to signal the main thread that // all threads in the pool have completed their work tthread::mutex m_WorkCompleted_mutex; tthread::condition_variable m_WorkCompleted_condvar; }; cpp file: // // ThreadPool.cpp // #include "ThreadPool.h" // This is the thread function for each thread. // All threads remain in this function until // they are asked to quit, which only happens // when terminating the thread pool. void ThreadPool::ThreadFunc( int threadId ) { ThreadData *myThreadData = &m_ThreadData[threadId]; std::cout << "Hello world: Thread " << threadId << std::endl; // Signal that this thread is ready m_ThreadReady_mutex.lock(); myThreadData->ready = true; m_ThreadReady_condvar.notify_one(); // notify the main thread m_ThreadReady_mutex.unlock(); while(true) { //tthread::lock_guard<tthread::mutex> guard(m); m_WorkToDo_mutex.lock(); while(!myThreadData->haveWorkToDo) // check for work to do m_WorkToDo_condvar.wait(m_WorkToDo_mutex); // if no work, wait here myThreadData->haveWorkToDo = false; // need to do this before unlocking the mutex m_WorkToDo_mutex.unlock(); // Do the work switch(myThreadData->typeOfWork) { case e_work: std::cout << "Thread " << threadId << ": Woken with work to do\n"; // Do work myThreadData->workFunc(myThreadData->workData); std::cout << "#Thread " << threadId << ": Work is completed\n"; break; case e_quit: std::cout << "Thread " << threadId << ": Asked to quit\n"; return; // ends the thread } // Now to signal the main thread that my work is completed m_WorkCompleted_mutex.lock(); m_NumOfThreadsDoingWork--; // Unsure if this 'if' would make the program more efficient // if(NumOfThreadsDoingWork == 0) m_WorkCompleted_condvar.notify_one(); // notify the main thread m_WorkCompleted_mutex.unlock(); } } ThreadPool::ThreadPool() { m_numOfThreads = 0; m_NumOfThreadsDoingWork = 0; m_NumOfThreadsGivenJobs = 0; } ThreadPool::~ThreadPool() { if(m_numOfThreads) { DestroyThreadPool(); delete [] m_ThreadData; } } void ThreadPool::CreateThreads(int numOfThreads) { // Check a thread pool has already been created if(m_numOfThreads > 0) return; m_NumOfThreadsGivenJobs = 0; m_NumOfThreadsDoingWork = 0; m_numOfThreads = numOfThreads; m_ThreadData = new ThreadData[m_numOfThreads]; ThreadArgStruct threadArg; for(int i=0; i<m_numOfThreads; ++i) { threadArg.threadId = i; threadArg.threadPoolInstance = this; // Creates the thread and save in a list so we can destroy it later m_ThreadList.push_back( new tthread::thread( ThreadFuncWrapper, (void *)&threadArg ) ); // It takes a little time for a thread to get established. // Best wait until it gets established before creating the next thread. m_ThreadReady_mutex.lock(); while(!m_ThreadData[i].ready) // Check if thread is ready m_ThreadReady_condvar.wait(m_ThreadReady_mutex); // If not, wait here m_ThreadReady_mutex.unlock(); } } // Adds a job to the batch, but doesn't start the job void ThreadPool::SubmitJob(void (*workFunc)(void *), void *workData) { // Check that the thread pool has been created if(!m_numOfThreads) return; if(m_NumOfThreadsGivenJobs >= m_numOfThreads) return; m_ThreadData[m_NumOfThreadsGivenJobs].workFunc = workFunc; m_ThreadData[m_NumOfThreadsGivenJobs].workData = workData; std::cout << "Submitted job " << m_NumOfThreadsGivenJobs << std::endl; m_NumOfThreadsGivenJobs++; } void ThreadPool::StartJobs() { // Check that the thread pool has been created // and some jobs have been assigned if(!m_numOfThreads || !m_NumOfThreadsGivenJobs) return; // Set 'haveworkToDo' flag for all threads m_WorkToDo_mutex.lock(); for(int i=0; i<m_NumOfThreadsGivenJobs; ++i) m_ThreadData[i].haveWorkToDo = true; m_NumOfThreadsDoingWork = m_NumOfThreadsGivenJobs; // Reset this counter so we can resubmit jobs later m_NumOfThreadsGivenJobs = 0; // Notify all threads they have work to do m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); } void ThreadPool::WaitForJobsToComplete() { // Check that a thread pool has been created if(!m_numOfThreads) return; m_WorkCompleted_mutex.lock(); while(m_NumOfThreadsDoingWork > 0) // Check if all threads have completed their work m_WorkCompleted_condvar.wait(m_WorkCompleted_mutex); // If not, wait here m_WorkCompleted_mutex.unlock(); } void ThreadPool::DestroyThreadPool() { std::cout << "Ask threads to quit\n"; m_WorkToDo_mutex.lock(); for(int i=0; i<m_numOfThreads; ++i) { m_ThreadData[i].haveWorkToDo = true; m_ThreadData[i].typeOfWork = e_quit; } m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); // As each thread terminates, catch them here for(int i=0; i<m_numOfThreads; ++i) { tthread::thread *t = m_ThreadList[i]; // Wait for thread to complete t->join(); } m_numOfThreads = 0; } Example of usage: (this calculates pi-squared/6) struct CalculationDataStruct { int inputVal; double outputVal; }; void LongCalculation( void *theSums ) { CalculationDataStruct *sums = (CalculationDataStruct *)theSums; int terms = sums->inputVal; double sum; for(int i=1; i<terms; i++) sum += 1.0/( double(i)*double(i) ); sums->outputVal = sum; } int main(int argc, char** argv) { int numThreads = 10; // Create pool ThreadPool threadPool; threadPool.CreateThreads(numThreads); // Create thread workspace CalculationDataStruct sums[numThreads]; // Set up jobs for(int i=0; i<numThreads; i++) { sums[i].inputVal = 3000*(i+1); threadPool.SubmitJob(LongCalculation, &sums[i]); } // Run the jobs threadPool.StartJobs(); threadPool.WaitForJobsToComplete(); // Print results for(int i=0; i<numThreads; i++) std::cout << "Sum of " << sums[i].inputVal << " terms is " << sums[i].outputVal << std::endl; return 0; } Question: In the ThreadPool::ThreadFunc method, would better performance be obtained if the following if statement if(NumOfThreadsDoingWork == 0) was included? Also, I'd be grateful of criticisms and ways to improve the code. At the same time, I hope the code is of use to others.

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• Optimized OCR black/white pixel algorithm

  - by eagle

  I am writing a simple OCR solution for a finite set of characters. That is, I know the exact way all 26 letters in the alphabet will look like. I am using C# and am able to easily determine if a given pixel should be treated as black or white. I am generating a matrix of black/white pixels for every single character. So for example, the letter I (capital i), might look like the following: 01110 00100 00100 00100 01110 Note: all points, which I use later in this post, assume that the top left pixel is (0, 0), bottom right pixel is (4, 4). 1's represent black pixels, and 0's represent white pixels. I would create a corresponding matrix in C# like this: CreateLetter("I", new List<List<bool>>() { new List<bool>() { false, true, true, true, false }, new List<bool>() { false, false, true, false, false }, new List<bool>() { false, false, true, false, false }, new List<bool>() { false, false, true, false, false }, new List<bool>() { false, true, true, true, false } }); I know I could probably optimize this part by using a multi-dimensional array instead, but let's ignore that for now, this is for illustrative purposes. Every letter is exactly the same dimensions, 10px by 11px (10px by 11px is the actual dimensions of a character in my real program. I simplified this to 5px by 5px in this posting since it is much easier to "draw" the letters using 0's and 1's on a smaller image). Now when I give it a 10px by 11px part of an image to analyze with OCR, it would need to run on every single letter (26) on every single pixel (10 * 11 = 110) which would mean 2,860 (26 * 110) iterations (in the worst case) for every single character. I was thinking this could be optimized by defining the unique characteristics of every character. So, for example, let's assume that the set of characters only consists of 5 distinct letters: I, A, O, B, and L. These might look like the following: 01110 00100 00100 01100 01000 00100 01010 01010 01010 01000 00100 01110 01010 01100 01000 00100 01010 01010 01010 01000 01110 01010 00100 01100 01110 After analyzing the unique characteristics of every character, I can significantly reduce the number of tests that need to be performed to test for a character. For example, for the "I" character, I could define it's unique characteristics as having a black pixel in the coordinate (3, 0) since no other characters have that pixel as black. So instead of testing 110 pixels for a match on the "I" character, I reduced it to a 1 pixel test. This is what it might look like for all these characters: var LetterI = new OcrLetter() { Name = "I", BlackPixels = new List<Point>() { new Point (3, 0) } } var LetterA = new OcrLetter() { Name = "A", WhitePixels = new List<Point>() { new Point(2, 4) } } var LetterO = new OcrLetter() { Name = "O", BlackPixels = new List<Point>() { new Point(3, 2) }, WhitePixels = new List<Point>() { new Point(2, 2) } } var LetterB = new OcrLetter() { Name = "B", BlackPixels = new List<Point>() { new Point(3, 1) }, WhitePixels = new List<Point>() { new Point(3, 2) } } var LetterL = new OcrLetter() { Name = "L", BlackPixels = new List<Point>() { new Point(1, 1), new Point(3, 4) }, WhitePixels = new List<Point>() { new Point(2, 2) } } This is challenging to do manually for 5 characters and gets much harder the greater the amount of letters that are added. You also want to guarantee that you have the minimum set of unique characteristics of a letter since you want it to be optimized as much as possible. I want to create an algorithm that will identify the unique characteristics of all the letters and would generate similar code to that above. I would then use this optimized black/white matrix to identify characters. How do I take the 26 letters that have all their black/white pixels filled in (e.g. the CreateLetter code block) and convert them to an optimized set of unique characteristics that define a letter (e.g. the new OcrLetter() code block)? And how would I guarantee that it is the most efficient definition set of unique characteristics (e.g. instead of defining 6 points as the unique characteristics, there might be a way to do it with 1 or 2 points, as the letter "I" in my example was able to). An alternative solution I've come up with is using a hash table, which will reduce it from 2,860 iterations to 110 iterations, a 26 time reduction. This is how it might work: I would populate it with data similar to the following: Letters["01110 00100 00100 00100 01110"] = "I"; Letters["00100 01010 01110 01010 01010"] = "A"; Letters["00100 01010 01010 01010 00100"] = "O"; Letters["01100 01010 01100 01010 01100"] = "B"; Now when I reach a location in the image to process, I convert it to a string such as: "01110 00100 00100 00100 01110" and simply find it in the hash table. This solution seems very simple, however, this still requires 110 iterations to generate this string for each letter. In big O notation, the algorithm is the same since O(110N) = O(2860N) = O(N) for N letters to process on the page. However, it is still improved by a constant factor of 26, a significant improvement (e.g. instead of it taking 26 minutes, it would take 1 minute). Update: Most of the solutions provided so far have not addressed the issue of identifying the unique characteristics of a character and rather provide alternative solutions. I am still looking for this solution which, as far as I can tell, is the only way to achieve the fastest OCR processing. I just came up with a partial solution: For each pixel, in the grid, store the letters that have it as a black pixel. Using these letters: I A O B L 01110 00100 00100 01100 01000 00100 01010 01010 01010 01000 00100 01110 01010 01100 01000 00100 01010 01010 01010 01000 01110 01010 00100 01100 01110 You would have something like this: CreatePixel(new Point(0, 0), new List<Char>() { }); CreatePixel(new Point(1, 0), new List<Char>() { 'I', 'B', 'L' }); CreatePixel(new Point(2, 0), new List<Char>() { 'I', 'A', 'O', 'B' }); CreatePixel(new Point(3, 0), new List<Char>() { 'I' }); CreatePixel(new Point(4, 0), new List<Char>() { }); CreatePixel(new Point(0, 1), new List<Char>() { }); CreatePixel(new Point(1, 1), new List<Char>() { 'A', 'B', 'L' }); CreatePixel(new Point(2, 1), new List<Char>() { 'I' }); CreatePixel(new Point(3, 1), new List<Char>() { 'A', 'O', 'B' }); // ... CreatePixel(new Point(2, 2), new List<Char>() { 'I', 'A', 'B' }); CreatePixel(new Point(3, 2), new List<Char>() { 'A', 'O' }); // ... CreatePixel(new Point(2, 4), new List<Char>() { 'I', 'O', 'B', 'L' }); CreatePixel(new Point(3, 4), new List<Char>() { 'I', 'A', 'L' }); CreatePixel(new Point(4, 4), new List<Char>() { }); Now for every letter, in order to find the unique characteristics, you need to look at which buckets it belongs to, as well as the amount of other characters in the bucket. So let's take the example of "I". We go to all the buckets it belongs to (1,0; 2,0; 3,0; ...; 3,4) and see that the one with the least amount of other characters is (3,0). In fact, it only has 1 character, meaning it must be an "I" in this case, and we found our unique characteristic. You can also do the same for pixels that would be white. Notice that bucket (2,0) contains all the letters except for "L", this means that it could be used as a white pixel test. Similarly, (2,4) doesn't contain an 'A'. Buckets that either contain all the letters or none of the letters can be discarded immediately, since these pixels can't help define a unique characteristic (e.g. 1,1; 4,0; 0,1; 4,4). It gets trickier when you don't have a 1 pixel test for a letter, for example in the case of 'O' and 'B'. Let's walk through the test for 'O'... It's contained in the following buckets: // Bucket Count Letters // 2,0 4 I, A, O, B // 3,1 3 A, O, B // 3,2 2 A, O // 2,4 4 I, O, B, L Additionally, we also have a few white pixel tests that can help: (I only listed those that are missing at most 2). The Missing Count was calculated as (5 - Bucket.Count). // Bucket Missing Count Missing Letters // 1,0 2 A, O // 1,1 2 I, O // 2,2 2 O, L // 3,4 2 O, B So now we can take the shortest black pixel bucket (3,2) and see that when we test for (3,2) we know it is either an 'A' or an 'O'. So we need an easy way to tell the difference between an 'A' and an 'O'. We could either look for a black pixel bucket that contains 'O' but not 'A' (e.g. 2,4) or a white pixel bucket that contains an 'O' but not an 'A' (e.g. 1,1). Either of these could be used in combination with the (3,2) pixel to uniquely identify the letter 'O' with only 2 tests. This seems like a simple algorithm when there are 5 characters, but how would I do this when there are 26 letters and a lot more pixels overlapping? For example, let's say that after the (3,2) pixel test, it found 10 different characters that contain the pixel (and this was the least from all the buckets). Now I need to find differences from 9 other characters instead of only 1 other character. How would I achieve my goal of getting the least amount of checks as possible, and ensure that I am not running extraneous tests?

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