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  • A Bit Cloudy

    - by Chris Massey
    "Systems Administrators, I come in peace. You have nothing to fear from me" - Office 365 Microsoft Business Productivity Online Suite recently absorbed a few other services and has been rebranded as Office 365, which is currently in private Beta and NDA-d up to the eyeballs. As Microsoft's (slightly delayed) answer to Google Apps Premier Edition, it shows a lot of promise; MS has technical expertise, market penetration, and financial capital all going for it. On the other hand, Google...(read more)

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  • Lifecycle Technology Delivers AutoVue Visualization Integration for SAP

    Lifecycle Technology is an Oracle development partner and has built a Connector for Oracle's AutoVue visualization solution and SAP. Their area of expertise lies in integrating AutoVue visualization and printing solutions with SAP business processes within Asset Lifecycle Management,Product Lifecycle Management,and Document Management Systems. Lifecycle visually enables a variety of SAP workflows and processes in manufacturing,plant maintenance,and production. Their solutions allow SAP enterprise customers to view technical or engineering documents in the appropriate business context and/or print them as required in their workflows, improving productivity and decision making.

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  • How can I distribute a unique database already in production?

    - by JVerstry
    Let's assume a successful web Spring application running on a MySQL or PostgreSQL database. The traffic is becoming so high and the amount of data is becoming so big that a distributed database solution needs to be implemented to address scalability issue. Let's also assume this application is using Hibernate and the data access layer is cleanly separated with DAOs. Ideally, one should be able to add or remove databases easily. A failback solution is welcome too. What would be the best strategy to scale this database? Is it possible to minimize sharding code (Shard) in the application?

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  • Partner Up for FY13: LIVE Oracle PartnerNetwork Kickoff is June 26-27

    - by oracletechnet
    Work for an Oracle partner? Then this is appointment viewing: On June 26-27, in different time zones worldwide, Oracle PartnerNetwork is live-streaming its FY13 Partner Kickoff. SVP Alliance & Channels Judson Althoff will join other technical executives, including Thomas Kurian (EVP Software Development) and John Fowler (EVP Hardware & Systems), to discuss the full range of business opportunities now available to Oracle partners. Register for your regional Webcast today. 

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  • ObjectBuilder

    - by csharp-source.net
    ObjectBuilder is a framework for building dependency injection systems, originally written by the Microsoft patterns and practices group. Using ObjectBuilder, it's possible to build DI containers that mimic a variety of existing containers.

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  • What common term could be used for Web Services, Windows Services etc

    - by Shamim Hafiz
    My question is primarily concerned with making a CV. Normally under the Language section we list the individual programming Languages we've used. For example, C#, C++, PHP. Under the Platform section we can list the various operating systems and devices. Under which category would Web Services/Windows Services fall? My point is these are not platforms by themselves and surely they aren't a language. Is there any common term that can be used to describe these?

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  • BI Applications overview

    - by sv744
    Welcome to Oracle BI applications blog! This blog will talk about various features, general roadmap, description of functionality and implementation steps related to Oracle BI applications. In the first post we start with an overview of the BI apps and will delve deeper into some of the topics below in the upcoming weeks and months. If there are other topics you would like us to talk about, pl feel free to provide feedback on that. The Oracle BI applications are a set of pre-built applications that enable pervasive BI by providing role-based insight for each functional area, including sales, service, marketing, contact center, finance, supplier/supply chain, HR/workforce, and executive management. For example, Sales Analytics includes role-based applications for sales executives, sales management, as well as front-line sales reps, each of whom have different needs. The applications integrate and transform data from a range of enterprise sources—including Siebel, Oracle, PeopleSoft, SAP, and others—into actionable intelligence for each business function and user role. This blog  starts with the key benefits and characteristics of Oracle BI applications. In a series of subsequent blogs, each of these points will be explained in detail. Why BI apps? Demonstrate the value of BI to a business user, show reports / dashboards / model that can answer their business questions as part of the sales cycle. Demonstrate technical feasibility of BI project and significantly lower risk and improve success Build Vs Buy benefit Don’t have to start with a blank sheet of paper. Help consolidate disparate systems Data integration in M&A situations Insulate BI consumers from changes in the OLTP Present OLTP data and highlight issues of poor data / missing data – and improve data quality and accuracy Prebuilt Integrations BI apps support prebuilt integrations against leading ERP sources: Fusion Applications, E- Business Suite, Peoplesoft, JD Edwards, Siebel, SAP Co-developed with inputs from functional experts in BI and Applications teams. Out of the box dimensional model to source model mappings Multi source and Multi Instance support Rich Data Model    BI apps have a very rich dimensionsal data model built over 10 years that incorporates best practises from BI modeling perspective as well as reflect the source system complexities  Thanks for reading a long post, and be on the lookout for future posts.  We will look forward to your valuable feedback on these topics as well as suggestions on what other topics would you like us to cover. I Conformed dimensional model across all business subject areas allows cross functional reporting, e.g. customer / supplier 360 Over 360 fact tables across 7 product areas CRM – 145, SCM – 47, Financials – 28, Procurement – 20, HCM – 27, Projects – 18, Campus Solutions – 21, PLM - 56 Supported by 300 physical dimensions Support for extensive calendars; Gregorian, enterprise and ledger based Conformed data model and metrics for real time vs warehouse based reporting  Multi-tenant enabled Extensive BI related transformations BI apps ETL and data integration support various transformations required for dimensional models and reporting requirements. All these have been distilled into common patterns and abstracted logic which can be readily reused across different modules Slowly Changing Dimension support Hierarchy flattening support Row / Column Hybrid Hierarchy Flattening As Is vs. As Was hierarchy support Currency Conversion :-  Support for 3 corporate, CRM, ledger and transaction currencies UOM conversion Internationalization / Localization Dynamic Data translations Code standardization (Domains) Historical Snapshots Cycle and process lifecycle computations Balance Facts Equalization of GL accounting chartfields/segments Standardized values for categorizing GL accounts Reconciliation between GL and subledgers to track accounted/transferred/posted transactions to GL Materialization of data only available through costly and complex APIs e.g. Fusion Payroll, EBS / Fusion Accruals Complex event Interpretation of source data – E.g. o    What constitutes a transfer o    Deriving supervisors via position hierarchy o    Deriving primary assignment in PSFT o    Categorizing and transposition to measures of Payroll Balances to specific metrics to support side by side comparison of measures of for example Fixed Salary, Variable Salary, Tax, Bonus, Overtime Payments. o    Counting of Events – E.g. converting events to fact counters so that for example the number of hires can easily be added up and compared alongside the total transfers and terminations. Multi pass processing of multiple sources e.g. headcount, salary, promotion, performance to allow side to side comparison. Adding value to data to aid analysis through banding, additional domain classifications and groupings to allow higher level analytical reporting and data discovery Calculation of complex measures examples: o    COGs, DSO, DPO, Inventory turns  etc o    Transfers within a Hierarchy or out of / into a hierarchy relative to view point in hierarchy. Configurability and Extensibility support  BI apps offer support for extensibility for various entities as automated extensibility or part of extension methodology Key Flex fields and Descriptive Flex support  Extensible attribute support (JDE)  Conformed Domains ETL Architecture BI apps offer a modular adapter architecture which allows support of multiple product lines into a single conformed model Multi Source Multi Technology Orchestration – creates load plan taking into account task dependencies and customers deployment to generate a plan based on a customers of multiple complex etl tasks Plan optimization allowing parallel ETL tasks Oracle: Bit map indexes and partition management High availability support    Follow the sun support. TCO BI apps support several utilities / capabilities that help with overall total cost of ownership and ensure a rapid implementation Improved cost of ownership – lower cost to deploy On-going support for new versions of the source application Task based setups flows Data Lineage Functional setup performed in Web UI by Functional person Configuration Test to Production support Security BI apps support both data and object security enabling implementations to quickly configure the application as per the reporting security needs Fine grain object security at report / dashboard and presentation catalog level Data Security integration with source systems  Extensible to support external data security rules Extensive Set of KPIs Over 7000 base and derived metrics across all modules Time series calculations (YoY, % growth etc) Common Currency and UOM reporting Cross subject area KPIs (analyzing HR vs GL data, drill from GL to AP/AR, etc) Prebuilt reports and dashboards 3000+ prebuilt reports supporting a large number of industries Hundreds of role based dashboards Dynamic currency conversion at dashboard level Highly tuned Performance The BI apps have been tuned over the years for both a very performant ETL and dashboard performance. The applications use best practises and advanced database features to enable the best possible performance. Optimized data model for BI and analytic queries Prebuilt aggregates& the ability for customers to create their own aggregates easily on warehouse facts allows for scalable end user performance Incremental extracts and loads Incremental Aggregate build Automatic table index and statistics management Parallel ETL loads Source system deletes handling Low latency extract with Golden Gate Micro ETL support Bitmap Indexes Partitioning support Modularized deployment, start small and add other subject areas seamlessly Source Specfic Staging and Real Time Schema Support for source specific operational reporting schema for EBS, PSFT, Siebel and JDE Application Integrations The BI apps also allow for integration with source systems as well as other applications that provide value add through BI and enable BI consumption during operational decision making Embedded dashboards for Fusion, EBS and Siebel applications Action Link support Marketing Segmentation Sales Predictor Dashboard Territory Management External Integrations The BI apps data integration choices include support for loading extenral data External data enrichment choices : UNSPSC, Item class etc. Extensible Spend Classification Broad Deployment Choices Exalytics support Databases :  Oracle, Exadata, Teradata, DB2, MSSQL ETL tool of choice : ODI (coming), Informatica Extensible and Customizable Extensible architecture and Methodology to add custom and external content Upgradable across releases

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  • Survey results: Open source developer preferences

    We recently conducted a survey of open source developers to learn about their current preferences around hosting sites and source control systems.  The survey was primarily advertised via Twitter, and we tried to avoid pushing the survey among audiences that would be specifically oriented towards a particular site (for example we did not advertise the survey from the CodePlex twitter account). In total there were just under 500 responses, so a reasonable sample size although not necessarily enough to guarantee fully representative results.  One of the survey questions was what is your preferred operating system for development, and looking at the results they are particularly interesting when split by operating system preference because of how significant the difference is:   Table 1 - Preferences by what is preferred operating system for development   As you can see, the preferences among developers which prefer Windows is very different from Linux and Mac oriented developers.  Again, the question was on what operating system they prefer to use for development, and didn’t ask what type of applications they create, so presumably many create things like websites which are cross-platform from a user perspective regardless of the operating system they prefer developing with. For hosting site preference, CodePlex and GitHub are roughly tied for first place among Windows developers and combined are preferred by over 75%.  However with Linux and Mac developers, GitHub has a runaway lead over the other sites.  Perhaps not particularly surprising, CodePlex has negligible mindshare among Linux and Mac developers.  It is somewhat surprising how low SourceForge and Google Code are given historically they used to rank much higher. Looking at version control preferences is also interesting.  Among Windows developers TFS, Mercurial, Subversion, and Git all have a sizable following.  While for Linux and Mac developers it is almost all Git and Mercurial, with Git having a substantial lead.  Git is generally considered to run better on Linux and have more of a Unix feel, so not really surprising to see it more popular there compared to Windows developers.  It is surprising how low Subversion has dropped since it was the dominant preference not long ago for open source developers.  Around a quarter of Windows developers still prefer Subversion, but Linux and Mac developers have largely abandoned it.  The trend towards distributed version control systems (e.g. Mercurial and Git) is strong, with over 50% of Windows developers now prefer DVCS, and over 80% of Linux and Mac developers.

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  • Speaking this week at Richmond SQL Server User Group

    - by drsql
    Thursday night, at 6:00 (or so) I will be speaking in Richmond ( http://richmondsql.org/cs2007/ ), talking about How to Implement a Hierarchy using SQL Server. The abstract is: One of the most common structures you will come across in the real world is a hierarchy (either a single parent "tree" or a multi-parent "graph"). Many systems will implement the obvious examples, such as a corporate managerial structure or a bill of materials. It turns out that almost any many-to-many relationship can be...(read more)

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  • A starting point for Use Cases and User Stories

    - by Mike Benkovich
    Originally posted on: http://geekswithblogs.net/benko/archive/2013/07/23/a-starting-point-for-use-cases-and-user-stories.aspxSoftware is a challenging business and is rife with opportunities to go wrong. Over the years a number of methodologies have evolved to help make sure that things go right. In an effort to contribute to this I’ve created a list of user stories that I think should be included and sometimes are just assumed. Note this is a work in progress, so I’m looking for your feedback. I’m curious what you would add or change in my list. · As a DBA I am working with a Normalized data model that reflects an agreed upon logical model for the system · As a DBA I am using consistent names for my fields which match the naming standards of my organization · As a DBA my model supports simple CRUD operations against all the entities · As an Application Architect the UI has been validated against the Business requirements and a complete set of user story’s have been created · As an Application Architect the database model has been validated against the UI · As an Application Architect we have a logical business model that describes all the known and/or expected usage of the system during the software’s expected lifecycle · As an Application Architect we have a Deployment diagram that describes how the application components will be deployed · As an Application Architect we have a navigation diagram that describes the typical application flow · As an Application Architect we have identified points of interaction which describes how the UI interacts with the services and the data storage · As an Application Architect we have identified external systems which may now or in the future use the data of this application and have adapted the logical model to include these interactions · As an Application Architect we have identified existing systems and tools that can be extended and/or reused to help this application achieve it’s business goals · As a Project Manager all team members understand the goals of each release and iteration as they are planned · As a Project Manager all team members understand their role and the roles of others · As a Project Manager we have support of the business to do the right thing even if it is not the expedient thing · As a Test/QA Analyst we have created a simulation environment for testing the system which does not use sensitive data and accurately reflects the scenarios of all the data that will be supported by the system · As a Test/QA Analyst we have identified the matrix of supported clients used to access the system including the likely browsers, mobile devices and other interfaces to work with the application · As a Test/QA Analyst we have created exit criteria for each user story that match the requirements of the business story that was used to create them · As a Test/QA Analyst we have access to a Test environment that is isolated from production and staging environments · As a Test/QA Analyst there we have a way to reset the environment so we can rerun tests when a new version of the software becomes available · As a Test/QA Analyst I am able to automate portions of the test process Thoughts? -mike

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  • Manic Monday - More OpenWorld Solaris Sessions: Developers, Cloud, Customer Insights, Hardware Optimization

    - by Larry Wake
    We're overflowing with Monday sessions; literally more than one person can take in. Learn more about what's new in Oracle Solaris Studio, hear about the latest x86 and SPARC hardware optimizations, get some insights on cloud deployment strategies, and find out from your peers what they're doing with Oracle Solaris. If you're an OpenWorld attendee, go to to Schedule Builder to guarantee your space in any session or lab. See yesterday's blog post and the "Focus on Oracle Solaris" guide for even more sessions. Monday, October 1st: 10:45 AM - Maximizing Your SPARC T4 Oracle Solaris Application Performance(CON6382,  Marriott Marquis - Golden Gate C3) Hear how customers and commercial software partners have reached peak performance on SPARC T4 servers and engineered systems with Oracle Solaris Studio and its latest tools for analyzing, reporting, and improving runtime performance: Autoparallelizing, high-performance compilers Performance Analyzer (used to find performance hotspots) Thread Analyzer (to expose data races and deadlocks) Code Analyzer (used to discover latent memory corruption issues) 10:45 Cloud Formation: Implementing IaaS in Practice with Oracle Solaris(CON8787, Moscone South 302) Decisions, decisions--at the same time, we've got a session that covers why Oracle Solaris is the ideal OS for public or private clouds, IaaS or PaaS, with built-in features for elastic infrastructure, unrivaled security, superfast installation and deployment, nonstop availability, and crystal-clear observability. This session will include a customer study on how Oracle Solaris is used in the cloud today to implement the Oracle stack. 12:15 PM - Customer Insight: Oracle Solaris on Oracle Exadata, Oracle Exalogic, and SPARC SuperCluster(CON8760, Moscone South 270) Hear from customers what benefits they have realized from using the Oracle stack on Oracle Exadata and Oracle’s SPARC SuperCluster and from using Oracle Solaris on those engineered systems, taking advantage of built-in lightweight OS virtualization (Zones), enterprise reliability and scale, and other key features. 1:45 PM - Case Study: Mobile Tornado Uses Oracle Technology for Better RAS and TCO?(CON4281, Moscone West 2005) Mobile Tornado develops and markets instant communication platforms, replacing traditional radio networks with cellular networks. Its critical concern is uptime. Find out how they've used Oracle Solaris, Netra SPARC T4, and Oracle Solaris Cluster, including Oracle Solaris ZFS and Zones, for their Oracle Database deployments to improve reliability and drive down cost. 3:15 PM - Technical Panel: Developing High Performance Applications on Oracle Solaris(CON7196, Marriott Marquis - Golden Gate C2) Engineers from the Oracle Solaris, Oracle Database, and Oracle Tuxedo development teams, and Oracle ISV Engineering discuss how they develop high-performance enterprise applications that take advantage of Oracle's SPARC and x86 servers, with Oracle Solaris Studio and new Oracle Solaris 11 features. Topics will include developer tools, parallel frameworks, best practices, and methodologies, as well as insights and case studies on parallelizing and optimizing application performance on Oracle Solaris. Bring your best questions! 3:15 PM -  x86 Power Management with Oracle Solaris: Current State, Opportunities, and Future(CON6271, Moscone West 2012) Another option for this time slot: learn about how Intel Xeon and Oracle Solaris work together to reduce server power consumption. This presentation addresses some of the recent power management improvements in Oracle Solaris, opportunities to further improve energy efficiency, and some future directions for Oracle Solaris power management.

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  • Insight into GNU/Linux boot process

    <b>Musing with GNU/Linux:</b> "In this document we will take a look at the different aspects of the boot process. Such as the BIOS which is the first code which runs, the boot loaders that can load different operating systems, pass arguments to the kernel, load it from different sources like a hard drive, a flash, and network & finally the kernel itself."

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  • Webscale is all about sharding and its coming to SQL Azure

    - by simonsabin
    There are many that joke about developers always talking about webscale and needing to shard to be able to scale. In reality many systems, if not most, don’t need to be able to scale to numerous nodes because todays processing is so powerful. However in the cloud world where you don’t have 1 big box you have many little ones (instances) you need some way of sharding/federating/distributing data and load. I’ve mentioned before of a PDC presentation on whats coming in SQL Azure, well they’ve put some...(read more)

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  • Where can I find "magic numbers" for classic game play mechanics?

    - by MrDatabase
    I'd like to find some "magic numbers" for the classic helicopter game. For example the numbers that determine how fast the helicopter accelerates up and down. Also perhaps the "randomness" of the obstacles (uniformly distributed? Gaussian?). Where can I find these numbers? p.s. I don't care about the particular platform... Flash on the desktop browser is just as good as some implementation on a mobile device.

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  • Understanding the 'High Performance' meaning in Extreme Transaction Processing

    - by kyap
    Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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  • C#/.NET Little Wonders: Interlocked Read() and Exchange()

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Last time we discussed the Interlocked class and its Add(), Increment(), and Decrement() methods which are all useful for updating a value atomically by adding (or subtracting).  However, this begs the question of how do we set and read those values atomically as well? Read() – Read a value atomically Let’s begin by examining the following code: 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value { get { return _value; } } 6:  7: public void Increment() 8: { 9: Interlocked.Increment(ref _value); 10: } 11: } 12:  It uses an interlocked increment, as we discuss in my previous post (here), so we know that the increment will be thread-safe.  But, to realize what’s potentially wrong we have to know a bit about how atomic reads are in 32 bit and 64 bit .NET environments. When you are dealing with an item smaller or equal to the system word size (such as an int on a 32 bit system or a long on a 64 bit system) then the read is generally atomic, because it can grab all of the bits needed at once.  However, when dealing with something larger than the system word size (reading a long on a 32 bit system for example), it cannot grab the whole value at once, which can lead to some problems since this read isn’t atomic. For example, this means that on a 32 bit system we may read one half of the long before another thread increments the value, and the other half of it after the increment.  To protect us from reading an invalid value in this manner, we can do an Interlocked.Read() to force the read to be atomic (of course, you’d want to make sure any writes or increments are atomic also): 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value 6: { 7: get { return Interlocked.Read(ref _value); } 8: } 9:  10: public void Increment() 11: { 12: Interlocked.Increment(ref _value); 13: } 14: } Now we are guaranteed that we will read the 64 bit value atomically on a 32 bit system, thus ensuring our thread safety (assuming all other reads, writes, increments, etc. are likewise protected).  Note that as stated before, and according to the MSDN (here), it isn’t strictly necessary to use Interlocked.Read() for reading 64 bit values on 64 bit systems, but for those still working in 32 bit environments, it comes in handy when dealing with long atomically. Exchange() – Exchanges two values atomically Exchange() lets us store a new value in the given location (the ref parameter) and return the old value as a result. So just as Read() allows us to read atomically, one use of Exchange() is to write values atomically.  For example, if we wanted to add a Reset() method to our Incrementor, we could do something like this: 1: public void Reset() 2: { 3: _value = 0; 4: } But the assignment wouldn’t be atomic on 32 bit systems, since the word size is 32 bits and the variable is a long (64 bits).  Thus our assignment could have only set half the value when a threaded read or increment happens, which would put us in a bad state. So instead, we could write Reset() like this: 1: public void Reset() 2: { 3: Interlocked.Exchange(ref _value, 0); 4: } And we’d be safe again on a 32 bit system. But this isn’t the only reason Exchange() is valuable.  The key comes in realizing that Exchange() doesn’t just set a new value, it returns the old as well in an atomic step.  Hence the name “exchange”: you are swapping the value to set with the stored value. So why would we want to do this?  Well, anytime you want to set a value and take action based on the previous value.  An example of this might be a scheme where you have several tasks, and during every so often, each of the tasks may nominate themselves to do some administrative chore.  Perhaps you don’t want to make this thread dedicated for whatever reason, but want to be robust enough to let any of the threads that isn’t currently occupied nominate itself for the job.  An easy and lightweight way to do this would be to have a long representing whether someone has acquired the “election” or not.  So a 0 would indicate no one has been elected and 1 would indicate someone has been elected. We could then base our nomination strategy as follows: every so often, a thread will attempt an Interlocked.Exchange() on the long and with a value of 1.  The first thread to do so will set it to a 1 and return back the old value of 0.  We can use this to show that they were the first to nominate and be chosen are thus “in charge”.  Anyone who nominates after that will attempt the same Exchange() but will get back a value of 1, which indicates that someone already had set it to a 1 before them, thus they are not elected. Then, the only other step we need take is to remember to release the election flag once the elected thread accomplishes its task, which we’d do by setting the value back to 0.  In this way, the next thread to nominate with Exchange() will get back the 0 letting them know they are the new elected nominee. Such code might look like this: 1: public class Nominator 2: { 3: private long _nomination = 0; 4: public bool Elect() 5: { 6: return Interlocked.Exchange(ref _nomination, 1) == 0; 7: } 8: public bool Release() 9: { 10: return Interlocked.Exchange(ref _nomination, 0) == 1; 11: } 12: } There’s many ways to do this, of course, but you get the idea.  Running 5 threads doing some “sleep” work might look like this: 1: var nominator = new Nominator(); 2: var random = new Random(); 3: Parallel.For(0, 5, i => 4: { 5:  6: for (int j = 0; j < _iterations; ++j) 7: { 8: if (nominator.Elect()) 9: { 10: // elected 11: Console.WriteLine("Elected nominee " + i); 12: Thread.Sleep(random.Next(100, 5000)); 13: nominator.Release(); 14: } 15: else 16: { 17: // not elected 18: Console.WriteLine("Did not elect nominee " + i); 19: } 20: // sleep before check again 21: Thread.Sleep(1000); 22: } 23: }); And would spit out results like: 1: Elected nominee 0 2: Did not elect nominee 2 3: Did not elect nominee 1 4: Did not elect nominee 4 5: Did not elect nominee 3 6: Did not elect nominee 3 7: Did not elect nominee 1 8: Did not elect nominee 2 9: Did not elect nominee 4 10: Elected nominee 3 11: Did not elect nominee 2 12: Did not elect nominee 1 13: Did not elect nominee 4 14: Elected nominee 0 15: Did not elect nominee 2 16: Did not elect nominee 4 17: ... Another nice thing about the Interlocked.Exchange() is it can be used to thread-safely set pretty much anything 64 bits or less in size including references, pointers (in unsafe mode), floats, doubles, etc.  Summary So, now we’ve seen two more things we can do with Interlocked: reading and exchanging a value atomically.  Read() and Exchange() are especially valuable for reading/writing 64 bit values atomically in a 32 bit system.  Exchange() has value even beyond simply atomic writes by using the Exchange() to your advantage, since it reads and set the value atomically, which allows you to do lightweight nomination systems. There’s still a few more goodies in the Interlocked class which we’ll explore next time! Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked

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  • Need help identifing what resources (eg. In MIT OpenCourseWare) can help me prepare for a test [closed]

    - by jiewmeng
    I am entering uni soon. I can sit for a placement test to see if I elegible for exemptions. The details are http://www.comp.nus.edu.sg/undergraduates/TestScope11_12.html Or CS2100 Computer Organisation (please click title) The objective of this module is to familiarise students with the fundamentals of computing devices. Through this module students will understand the basics of data representation, and how the various parts of a computer work, separately and with each other. This allows students to understand the issues in computing devices, and how these issues affect the implementation of solutions. Topics covered include data representation systems, combinational and sequential circuit design techniques, assembly language, processor execution cycles, pipelining, memory hierarchy and input/output systems. Recommended Textbooks Digital Design: Principles and Practices [DDPP] by John F. Wakerly, Prentice-Hall. ISBN 0-13-324500-4. Computer Organizations and Design (The hardware/software interface) by David A. Patterson and John L. Hennessy. CS2105 Introduction to Computer Networks (please click title) This course aims to provide a broad introduction to computer networks and some appreciations of network application programming. It covers a range of topics including basic data communication and computer network concepts, protocols, networked computing concepts and principles, network applications development and network security. The emphasis of teaching is on the working principles and application of computer networks. As an integral part of the course, tutorials and practical assignments enforcing learning will also be given. These assignments provide an early exposure in network application programming and they should be able to complete by using personal computers and school's network facilities. Topics included: An overview of computer networks and the Internet Basic data communications Application layer Transport layer Network layer and routing Link layer and local area networks Recommended Textbook James F. Kurose & Keith W. Ross, Computer networking: A top-down approach featuring internet, Addison Wesley, 2001 I am wondering what resources eg. MIT OpenCourseWare or other universities resources are available to help he perpare for these particular modubles. I am thinking does the Networking one look like CCNA? The computer oragization. Its like electronics, assembly etc? I learnt some electronics in Poly but looking at the sample papers, uni looks very different... I have about 1 month to prepare if I want any chance of exempting from these modules :) any help?

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  • Using EPEL repos with Oracle Linux

    - by wcoekaer
    There's a Fedora project called EPEL which hosts a set of additional packages that can be installed on top of various distributions such as Red Hat Enterprise Linux, CentOS, Scientific Linux and of course also Oracle Linux. These packages are not distributed by the distribution vendor and as such also not supported by the vendors (including Oracle) however for users that want to pick up some extras that are useful, it's very easy to do this. All you need to do is download the EPEL RPM from the website, install it on Oracle Linux 5 or Oracle Linux 6 and run yum install or yum search to get the packages. example : # wget http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-5.noarch.rpm # rpm -ivh epel-release-6-5.noarch.rpm # yum repolist Loaded plugins: refresh-packagekit, rhnplugin repo id repo name status epel Extra Packages for Enterprise Linux 6 - x86_64 7,124 The folks that build these repositories are doing a great job at adding very useful packages. They are free, but also unsupported of course.

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  • Could not display chart. The control is not properly registered. (4 replies)

    I've seen other people raise this in searching the web but can't find any definitive answers so apologies if this has been answered previously (but please point me in that direction). I have two XP Pro SP2 workstations one works fine in that it shows the result graphs in ACT (v1.0.536.0) and the other gives the error &quot;Could not display chart. The control is not properly registered.&quot;. Both systems ...

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  • Looping 3D environment in shmups

    - by kamziro
    So I was watching Ikaruga: http://www.youtube.com/watch?v=Aj23K8Ri68E And then raystorm: http://www.youtube.com/watch?v=TQ4V0G5ykAg After looking at their 3D backgrounds for a little bit, it appears that they use a lot of repeated segments. How would one start with the development with such systems? Would there be editors that can be used (or at least help) with creating the environments? Perhaps a 3D map with splines describing the path of the ship, as well as events on the splines?

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  • Microsoft Plays the Open Source Software Game

    OS Roundup: Microsoft appears to have woken up to the fact that free open-source Office clones may be the thin end of a very slippery wedge. Its response is loud and clear, as it tells the world, when it comes to operating systems Microsoft intends to be a formidable competitor for some time to come.

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  • Microsoft Plays the Open Source Software Game

    OS Roundup: Microsoft appears to have woken up to the fact that free open-source Office clones may be the thin end of a very slippery wedge. Its response is loud and clear, as it tells the world, when it comes to operating systems Microsoft intends to be a formidable competitor for some time to come.

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  • Another question about handling game states

    - by Eva
    I'm making a game designed with the entity-component paradigm that uses systems to communicate between components as explained here. I've reached the point in my development that I need to add game states (such as paused, playing, level start, round start, game over, etc.), but I'm not sure how to do it with my framework. I've looked at this code example on game states which everyone seems to reference, but I don't think it fits with my framework. It seems to have each state handling its own drawing and updating. My framework has a SystemManager that handles all the updating using systems. For example, here's my RenderingSystem class: public class RenderingSystem extends GameSystem { private GameView gameView_; /** * Constructor * Creates a new RenderingSystem. * @param gameManager The game manager. Used to get the game components. */ public RenderingSystem(GameManager gameManager) { super(gameManager); } /** * Method: registerGameView * Registers gameView into the RenderingSystem. * @param gameView The game view registered. */ public void registerGameView(GameView gameView) { gameView_ = gameView; } /** * Method: triggerRender * Adds a repaint call to the event queue for the dirty rectangle. */ public void triggerRender() { Rectangle dirtyRect = new Rectangle(); for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); dirtyRect.add(graphicsComponent.getDirtyRect()); } gameView_.repaint(dirtyRect); } /** * Method: renderGameView * Renders the game objects onto the game view. * @param g The graphics object that draws the game objects. */ public void renderGameView(Graphics g) { for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); if (!graphicsComponent.isVisible()) continue; GraphicsComponent.Shape shape = graphicsComponent.getShape(); BoundsComponent boundsComponent = object.getComponent(BoundsComponent.class); Rectangle bounds = boundsComponent.getBounds(); g.setColor(graphicsComponent.getColor()); if (shape == GraphicsComponent.Shape.RECTANGULAR) { g.fill3DRect(bounds.x, bounds.y, bounds.width, bounds.height, true); } else if (shape == GraphicsComponent.Shape.CIRCULAR) { g.fillOval(bounds.x, bounds.y, bounds.width, bounds.height); } } } /** * Method: getRenderableObjects * @return The renderable game objects. */ private HashSet<GameObject> getRenderableObjects() { return gameManager.getGameObjectManager().getRelevantObjects( getClass()); } } Also all the updating in my game is event-driven. I don't have a loop like theirs that simply updates everything at the same time. I like my framework because it makes it easy to add new GameObjects, but doesn't have the problems some component-based designs encounter when communicating between components. I would hate to chuck it just to get pause to work. Is there a way I can add game states to my game without removing the entity-component design? Does the game state example actually fit my framework, and I'm just missing something?

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  • Problem downloading .exe file from Amazon S3 with a signed URL in IE

    - by Joe Corkery
    I have a large collection of Windows exe files which are being stored/distributed using Amazon S3. We use signed URLs to control access to the files and this works great except in one case when trying to download a .exe file using Internet Explorer (version 8). It works just fine in Firefox. It also works fine if you don't use a signed URL (but that is not an option). What happens is that the IE downloader changes the name from 'myfile.exe' to 'myfile[1]' and Windows no longer recognizes it as an executable. Any advice would greatly be appreciated. Thanks.

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  • Application Virtualization has challenges

    - by llaszews
    information Week article discusses the challenges associated virtualizing applications in the cloud: Application Virtualization Challenges 'Golden images' quickly diverge from their pristine initial condition because of: 1. OS patches 2. Application updates 3. Configuration changes "Applications, once released into the wild, tend to quickly diverge from the golden image" "The difficulties face by developers and systems admins in deploying apps to the cloud are reminiscent of those encountered transitioning from mainframe to the client/server era"

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