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  • Why are all logins disabled in the virtual terminal after enabling root account from desktop?

    - by Mitch
    Just for testing purposes, I went a head and enabled the root account, by using the commands below: sudo passwd root [sudo] password for abed: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully Once that happened, I went ahead and did Ctrl+Alt+F1, to get to the first virtual console, and at the login prompt I try logging in as abed, su, root, all comeback with login incorrect. Why is that happening, and how can I fix it.

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  • Responsive Design: Media query fix for IE10 on Windows Phone 8

    - by ihaynes
    Originally posted on: http://geekswithblogs.net/ihaynes/archive/2013/07/01/responsive-design-media-query-fix-for-ie10-on--windows.aspxThe version of IE10 on Windows Phone 8 apparently has a bug which results in media queries not seeing the correct device width.This post from Devhammer explains all.http://devhammer.net/responsive-design-fix-for-windows-phone-8-device-adaptationI'd not noticed this on the WP8 Emulator which proves yet again that testing on real devices is essential.

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  • Monitoring Your Servers

    - by Grant Fritchey
    If you are the DBA in a large scale enterprise, you’re probably already monitoring your servers for up-time and performance. But if you work for a medium-sized business, a small shop, or even a one-man operation, chances are pretty good that you’re not doing that sort of monitoring. You know that you’re supposed to be doing it, but other things, more important at-the-moment things, keep getting in the way. After all, which is more important, some monitoring or backup testing?  Backup testing, of course. Monitoring is frequently one of those things that you do when can get around to it.  Well, as you can see at the right, I have your round tuit ready to go. What if I told you that you could get monitoring on your servers for up-time, job completion, performance, all the standard stuff? And what if I told you that you wouldn’t need to install and configure another server in your environment to get it done? And what if I told you that you’d be able to set up and customize your alerts so you could know if your server was offline or a drive was full? Almost nothing for you to do, and you’ll have a full-blown monitoring process. Sounds to good to be true doesn’t it? Well, it’s coming. We’re creating an online, remote, monitoring system here at Red Gate. You’ll be able to use our SQL Monitor tool (which you can see here, monitoring SQL Server Central in real time) to keep track of your systems, but without having to set up a server and a database for storing the information collected. Instead, we’re taking advantage of services available through the internet to enable collection and storage of this information remotely, off your systems. All you have to do is install a piece of software that will communicate between our service and your servers and you’ll be off and running. It’s that easy. Before you get too excited, let me break the news that this is the near future I’m talking about. We’re setting up the program and there’s a sign-up you can use to get in on the initial tests.

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  • Curing the Database-Application mismatch

    - by Phil Factor
    If an application requires access to a database, then you have to be able to deploy it so as to be version-compatible with the database, in phase. If you can deploy both together, then the application and database must normally be deployed at the same version in which they, together, passed integration and functional testing.  When a single database supports more than one application, then the problem gets more interesting. I’ll need to be more precise here. It is actually the application-interface definition of the database that needs to be in a compatible ‘version’.  Most databases that get into production have no separate application-interface; in other words they are ‘close-coupled’.  For this vast majority, the whole database is the application-interface, and applications are free to wander through the bowels of the database scot-free.  If you’ve spurned the perceived wisdom of application architects to have a defined application-interface within the database that is based on views and stored procedures, any version-mismatch will be as sensitive as a kitten.  A team that creates an application that makes direct access to base tables in a database will have to put a lot of energy into keeping Database and Application in sync, to say nothing of having to tackle issues such as security and audit. It is not the obvious route to development nirvana. I’ve been in countless tense meetings with application developers who initially bridle instinctively at the apparent restrictions of being ‘banned’ from the base tables or routines of a database.  There is no good technical reason for needing that sort of access that I’ve ever come across.  Everything that the application wants can be delivered via a set of views and procedures, and with far less pain for all concerned: This is the application-interface.  If more than zero developers are creating a database-driven application, then the project will benefit from the loose-coupling that an application interface brings. What is important here is that the database development role is separated from the application development role, even if it is the same developer performing both roles. The idea of an application-interface with a database is as old as I can remember. The big corporate or government databases generally supported several applications, and there was little option. When a new application wanted access to an existing corporate database, the developers, and myself as technical architect, would have to meet with hatchet-faced DBAs and production staff to work out an interface. Sure, they would talk up the effort involved for budgetary reasons, but it was routine work, because it decoupled the database from its supporting applications. We’d be given our own stored procedures. One of them, I still remember, had ninety-two parameters. All database access was encapsulated in one application-module. If you have a stable defined application-interface with the database (Yes, one for each application usually) you need to keep the external definitions of the components of this interface in version control, linked with the application source,  and carefully track and negotiate any changes between database developers and application developers.  Essentially, the application development team owns the interface definition, and the onus is on the Database developers to implement it and maintain it, in conformance.  Internally, the database can then make all sorts of changes and refactoring, as long as source control is maintained.  If the application interface passes all the comprehensive integration and functional tests for the particular version they were designed for, nothing is broken. Your performance-testing can ‘hang’ on the same interface, since databases are judged on the performance of the application, not an ‘internal’ database process. The database developers have responsibility for maintaining the application-interface, but not its definition,  as they refactor the database. This is easily tested on a daily basis since the tests are normally automated. In this setting, the deployment can proceed if the more stable application-interface, rather than the continuously-changing database, passes all tests for the version of the application. Normally, if all goes well, a database with a well-designed application interface can evolve gracefully without changing the external appearance of the interface, and this is confirmed by integration tests that check the interface, and which hopefully don’t need to be altered at all often.  If the application is rapidly changing its ‘domain model’  in the light of an increased understanding of the application domain, then it can change the interface definitions and the database developers need only implement the interface rather than refactor the underlying database.  The test team will also have to redo the functional and integration tests which are, of course ‘written to’ the definition.  The Database developers will find it easier if these tests are done before their re-wiring  job to implement the new interface. If, at the other extreme, an application receives no further development work but survives unchanged, the database can continue to change and develop to keep pace with the requirements of the other applications it supports, and needs only to take care that the application interface is never broken. Testing is easy since your automated scripts to test the interface do not need to change. The database developers will, of course, maintain their own source control for the database, and will be likely to maintain versions for all major releases. However, this will not need to be shared with the applications that the database servers. On the other hand, the definition of the application interfaces should be within the application source. Changes in it have to be subject to change-control procedures, as they will require a chain of tests. Once you allow, instead of an application-interface, an intimate relationship between application and database, we are in the realms of impedance mismatch, over and above the obvious security problems.  Part of this impedance problem is a difference in development practices. Whereas the application has to be regularly built and integrated, this isn’t necessarily the case with the database.  An RDBMS is inherently multi-user and self-integrating. If the developers work together on the database, then a subsequent integration of the database on a staging server doesn’t often bring nasty surprises. A separate database-integration process is only needed if the database is deliberately built in a way that mimics the application development process, but which hampers the normal database-development techniques.  This process is like demanding a official walking with a red flag in front of a motor car.  In order to closely coordinate databases with applications, entire databases have to be ‘versioned’, so that an application version can be matched with a database version to produce a working build without errors.  There is no natural process to ‘version’ databases.  Each development project will have to define a system for maintaining the version level. A curious paradox occurs in development when there is no formal application-interface. When the strains and cracks happen, the extra meetings, bureaucracy, and activity required to maintain accurate deployments looks to IT management like work. They see activity, and it looks good. Work means progress.  Management then smile on the design choices made. In IT, good design work doesn’t necessarily look good, and vice versa.

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  • E-Business Suite Sessions at Sangam 2013 in Hyderabad

    - by Sara Woodhull
    The Sangam 2013 conference, sponsored jointly by the All-India Oracle Users' Group (AIOUG) and India Oracle Applucations Users Group (IOAUG), will be in Hyderabad, India on November 8-9, 2013.  This year, the E-Business Suite Applications Technology Group (ATG) will offer two speaker sessions and a walk-in usability test of upcoming EBS user interface features.  It's only about two weeks away, so make your plans to attend if you are in India. Sessions Oracle E-Business Suite Technology: Latest Features and Roadmap Veshaal Singh, Senior Director, ATG Development Friday, Nov. 9, 11:00-12:00 This Oracle development session provides an 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 Oracle E-Business Suite technology. 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. Integration Options for Oracle E-Business Suite Rekha Ayothi, Lead Product Manager, ATG Friday, Nov. 9, 2:00-3:00 In this Oracle development 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. This session 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 options for integrating Oracle E-Business Suite with other applications. Usability Testing There will be multiple opportunities to participate in usability testing at Sangam '13.  The User Experience team is running a one-on-one usability study that requires advance registration.  In addition, we will be hosting a special walk-in usability lab to get feedback for new Oracle E-Business Suite OA Framework features.  The walk-in lab is a shorter usability experience that does not require any pre-registration.  In both cases, Oracle wants your feedback!  Even if you only have a few minutes, come by the User Experience Lab, meet the team, and try the walk-in lab.

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  • Creating a Successful Cloud Roadmap

    - by stephen.g.bennett
    No matter what type of cloud services or deployment models you are considering as part of your overall IT strategy, you must have a cloud services adoption roadmap to guide your journey. A cloud services adoption roadmap provides guidance that enables multiple projects to progress in parallel yet remain coordinated and ultimately result in a common end goal. The cloud services adoption roadmap consists of program-level efforts and a portfolio of cloud services. The program-level effort creates strategic assets such as the cloud architecture, cloud infrastructure, cloud governance, risk, and compliance (GRC) processes, and security policies that are leveraged across all the individual projects. A feature article on this topic can be found in the latest SOA and Cloud Magazine.

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  • Oracle European Launch Event: Oracle Database In-Memory

    - by A&C Redaktion
    am 17. Juni wird Andy Mendelsohn,  Oracle Executive Vice President Database Server Technologies, als Keynote Speaker den europäischen Launch von  Oracle Database In-Memory  in Frankfurt im Radisson Blue Hotel eröffnen. Dieses Thema ist für unsere Partner und Kunden von zentraler Bedeutung. Daher ist auch die Agenda dieses Launch Events einzigartig:Neben Vorträgen von Betakunden (Postbank und Cern), dem Analysten von IDC, der auch beim HQ Launch eine Woche zuvor in Redwood Shores mit Larry Ellison auf der Bühne stehen wird, und weiteren Oracle-Experten finden auch Live Demos statt. Eine Podiumsdiskussion rundet das Programm ab. Parallel zum Event werden Presse- und Analystengespräche geführt.Mit der neuen, bahnbrechenden Oracle Database In-Memory Option profitieren Kunden von einer erheblich beschleunigten Datenbankleistung für Analytics, Data Warehousing, Reporting und Online Transaction Processing (OLTP).Das ist so revolutionär, dass wir hiermit alle unsere Partner und ihre Endkunden zu diesem herausragenden Event herzlich einladen .Hier können Sie sich und Ihre Endkunden zu dieser exklusiven Live-Veranstaltung anmelden

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  • Oracle European Launch Event: Oracle Database In-Memory

    - by A&C Redaktion
    am 17. Juni wird Andy Mendelsohn,  Oracle Executive Vice President Database Server Technologies, als Keynote Speaker den europäischen Launch von  Oracle Database In-Memory  in Frankfurt im Radisson Blue Hotel eröffnen. Dieses Thema ist für unsere Partner und Kunden von zentraler Bedeutung. Daher ist auch die Agenda dieses Launch Events einzigartig:Neben Vorträgen von Betakunden (Postbank und Cern), dem Analysten von IDC, der auch beim HQ Launch eine Woche zuvor in Redwood Shores mit Larry Ellison auf der Bühne stehen wird, und weiteren Oracle-Experten finden auch Live Demos statt. Eine Podiumsdiskussion rundet das Programm ab. Parallel zum Event werden Presse- und Analystengespräche geführt.Mit der neuen, bahnbrechenden Oracle Database In-Memory Option profitieren Kunden von einer erheblich beschleunigten Datenbankleistung für Analytics, Data Warehousing, Reporting und Online Transaction Processing (OLTP).Das ist so revolutionär, dass wir hiermit alle unsere Partner und ihre Endkunden zu diesem herausragenden Event herzlich einladen .Hier können Sie sich und Ihre Endkunden zu dieser exklusiven Live-Veranstaltung anmelden

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  • Views from Abroad: XML Pipelines and Delta XML

    A U.K.-based company uses XML to replicate the advantages of a pipeline in handling complex datasets. It is a simple tool, useful for such tasks as Java regression testing and version control, but the few tricks it does, it does well, according to our columnist.

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  • EXT2 on Windows - a Year later

    <b>Matthew Casperson's Hubfolio:</b> "Traditionally the solution is a common partition formatted with FAT32, but instead of making Linux do the hard work of interacting with Windows, I thought I would try it the other way around. This is how I found myself testing both Ext2Fsd and Ext IFS For Windows."

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  • Beginning with first project on game development [closed]

    - by Tsvetan
    Today is the day I am going to start my first real game project. It will be a Universe simulator. Basically, you can build anything from tiny meteor to quazars and universes. It is going to be my project for an olympiad in IT in my country and I really want to make it perfect(at least a bronze medal). So, I would like to ask some questions about organization and development methodologies. Firstly, my plan is to make a time schedule. In it I would write my plans for the next month or two(because that is the time I have). With this exact plan I hope to make my organisation at its best. Of course, if I am doing sth faster than the schedule I would involve more features for the game and/or continue with the tempo I have. Also, for the organisation I would make a basic pseudocode(maybe) and just rewrite it so it is compilable. Like a basic skeleton of everything. The last is an idea I tought of in the moment, but if it is good I will use it. Secondly, for the development methodologies, obviously, I think of making object-oriented code and make everything perfect(a lot of testing, good code, documentation etc.). Also, I am going to make my own menu system(I read that OpenGL hasn't got very good one). Maybe I would implement it with an xml file, holding the info about position of buttons, text boxes, images and everything. Maybe I would do a specific CSS for it and so on. I think that is very good way of doing the menu system, because it makes the presentation layer separate of the logic. But, if there is a better way, I would do it the better way. For the logic, well, I don't have much to say. OO code, testing, debuging, good and fast algorithms and so on. Also, a good documentation must be written and this is the area I need to make some research in. I think that is for now. I hope I have been enough descriptive. If more questions come on my mind, I will ask them. Edit: I think of blogging every part of the project, or at least writing down everything in a file or something like that. My question is: Is my plan of how to do everything around the project good? And if not, what is necessary to be improved and what other things I can involve for making the project good.

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  • WebCenter Customer Spotlight: College of American Pathologists

    - by me
    Author: Peter Reiser - Social Business Evangelist, Oracle WebCenter  Solution Summary College of American Pathologists Goes Live with OracleWebCenter - Imaging, AP Invoice Automation, and EBS Managed Attachment with Support for Imaging ContentThe College of American Pathologists (CAP), the leading organization of board-certified pathologists serving more then 18,000 physician members, 7,000 laboratories are accredited by the CAP, and approximately 22,000 laboratories are enrolled in the College’s proficiency testing programs. The business objective was to content-enable their Oracle E-Business Suite (EBS) enterprise application by combining the best of Imaging and Manage Attachment functionality providing a unique opportunity for the business to have unprecedented access to both structure and unstructured content from within their enterprise application. The solution improves customer services turnaround time, provides better compliance and improves maintenance and management of the technology infrastructure. Company OverviewThe College of American Pathologists (CAP), celebrating 50 years as the gold standard in laboratory accreditation, is a medical society serving more than 17,000 physician members and the global laboratory community. It is the world’s largest association composed exclusively of board certified pathologists and is the worldwide leader in laboratory quality assurance. The College advocates accountable, high-quality, and cost-effective patient care. The more than 17,000 pathologist members of the College of American Pathologists represent board-certified pathologists and pathologists in training worldwide. More than 7,000 laboratories are accredited by the CAP, and approximately 23,000 laboratories are enrolled in the College’s proficiency testing programs.  Business ChallengesThe CAP business objective was to content-enable their Oracle E-Business Suite (EBS) enterprise application by combining the best of Imaging and Manage Attachment functionality providing a unique opportunity for the business to have unprecedented access to both structure and unstructured content from within their enterprise application.  Bring more flexibility to systems and programs in order to adapt quickly Get a 360 degree view of the customer Reduce cost of running the business Solution DeployedWith the help of Oracle Consulting, the customer implemented Oracle WebCenter Content as the centralized E-Business Suite Document Repository.  The solution enables to capture, present and manage all unstructured content (PDFs,word processing documents, scanned images, etc.) related to Oracle E-Business Suite transactions and exposing the related content using the familiar EBS User Interface. Business ResultsThe CAP achieved following benefits from the implemented solution: Managed Attachment Solution Align with strategic Oracle Fusion Middleware platform Integrate with the CAP existing data capture capabilities Single user interface provided by the Managed Attachment solution for all content Better compliance and improved collaboration  Account Payables Invoice Processing Imaging Solution Automated invoice management eliminating dependency on paper materials and improving compliance, collaboration and accuracy A single repository to house and secure scanned invoices and all supplemental documents Greater management visibility of invoice entry process Additional Information CAP OpenWorld Presentation Oracle WebCenter Content Oracle Webcenter Capture Oracle WebCenter Imaging Oracle  Consulting

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  • how do you manage application performance reviews

    - by CoolBeans
    I have been trying to figure out ways to effectively do performance reviews before an install happens for all releases done by our team. Do you usually make this a part of code review process or do you handle it as a separate review task? FYI - we do not have a dedicated performance testing team. It is up to the developers to make sure the app performs well. The apps I am referring to are web applications.

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  • Imon RM200 remote (device 15c2:ffdc) won't work on Ubuntu 12.04 or 11.10

    - by skerit
    The device is recognized just fine: Bus 001 Device 005: ID 15c2:ffdc SoundGraph Inc. iMON PAD Remote Controller Found /sys/class/rc/rc0/ (/dev/input/event6) with: Driver imon, table rc-imon-mce Supported protocols: RC-6 Enabled protocols: RC-6 Repeat delay = 500 ms, repeat period = 125 ms But any testing results in nothing. I point the remote, I press a few button and nothing happens. Not in irw, not in ir-keytable, nothing. It's driving me insane.

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  • Advanced 2D and 3D Design Tools in ZWCAD 2010

    Last time I introduced you my initial experiences with a powerful CAD software - ZWCAD 2010 (http://www.zwcad.org/products_download_list.php?id=107). As I continued with my testing, I found more surp... [Author: Damian Chloe - Computers and Internet - March 29, 2010]

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  • Is Unix/Linux adoption a measure of developer skill? [closed]

    - by adeptsage
    Is Linux/Unix based OS adoption for development (or recreation) a rough measure of the awareness, adaptability and/or skill of a developer, after considering factors like learning curve for effective code testing via the CLI, basic scripting, tweaking, etc. I have no intention of starting flame wars between Windows and Linux as better dev environments, and personal choice of OSes for dev, but what i do wish to know is that - will the level of adaptability of a person who uses a Unix based system be defined by the fact that he programs on a Unix based OS?

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  • Announcement Oracle Solaris 11.1 Availability!

    - by uwes
    On 25th of October Oracle announced the availability of Oracle Solaris 11.1. Highlights include: 8x faster database startup and shutdown and online resizing of the database SGA with a new optimized shared memory interface between the database and Oracle Solaris 11.1 Up to 20% throughput increases for Oracle Real Application Clusters by offloading lock management into the Oracle Solaris kernel Expanded support for Software Defined Networks (SDN) with Edge Virtual Bridging enhancements to maximize network resource utilization and manage bandwidth in cloud environments 4x faster Solaris Zone updates with parallel operations shorten maintenance windows New built-in memory predictor monitors application memory use and provides optimized memory page sizes and resource location to speed overall application performance. More information could be found under the following links: Oracle Solaris 11.1 Data Sheet  What's New in Oracle Solaris 11.1 Oracle Solaris 11.1 FAQs Oracle.com Oracle Solaris page Oracle Technology Network Oracle Solaris page Resources for downloading: Download Solaris 11.1 Order Solaris 11.1 media kit Existing customers can quickly and simply update using the network based repository

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  • Save the date! Manageability Partner Community Forum at Oracle Openworld - Oct. 1st

    - by Javier Puerta
    The Exadata & Manageability Partner Communities will be celebrating a Community Forum in San Francisco during Oracle Openworld. The session will take place on Monday, October 1st, from 4:00 - 6:00 pm local time.If you would like to present an experience around a customer project or sales best practice in the Manageability or Quality & Testing areas, please contact [email protected] with a short description of your proposal.

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  • TestRail 1.0 Test Management Software released

    Gurock Software just released its new test management solution TestRail. TestRail is a web-based test case management software that helps software development teams and QA departments to efficiently manage, track and organize software testing efforts.

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  • C#/.NET Little Wonders: The Generic Func Delegates

    - 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. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET.  Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates.  For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method.  They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression.  They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3:  4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6:  7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9:  10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET.  These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic.  Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results.  Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void.  You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result.  Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…).  To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total.  A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5:  6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8:  9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13:  14: _aggregationMethod = aggregationMethod; 15: } 16:  17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3:  4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5:  6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10:  11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them.  So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2:  3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6:  7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain.  Thus, this aggregator would always result in the Math.Max() result.  The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4:  5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8:  9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments.  In addition, it is co-variant on its return type.  To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders.  As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived.  However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object.  In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals.  On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived.  Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result.  In other words, pay attention to the direction the item travels (parameters go in, results come out).  Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5:  6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11:  12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3:  4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate.  Predicates are used to examine an item and determine whether that item satisfies a particular condition.  Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2:  3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine.  Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4:  5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types!  Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4:  5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8:  9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day.  We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day.  This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing.  Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds.  Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6:  7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13:  14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16:  17: // the item cached 18: public T Value { get; private set; } 19:  20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25:  26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2:  3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5:  6: var target = new CacheItem<int>(13); 7:  8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10:  11: Assert.IsFalse(target.IsExpired); 12:  13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15:  16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc.  Func delegates can be a handy tool for this type of value generation to support more testable code.  Summary Generic delegates give us a lot of power to make truly generic algorithms and classes.  The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments.  Stay tuned in the weeks that follow for other generic delegates in the .NET Framework!   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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  • Example sites which use UCC certificates

    - by Brian
    Can anyone point me to a few sites that make use of a UCC (SAN) certificates? I tried to search for this but found a lot of information about UCC certficates without any examples. As a sanity check before buying/configuring a UCC certificate, I wish to do some basic testing to determine exactly how the certificate will look in different browsers. Yes, I realize I could just use makecert instead. I would rather just look at them in the wild.

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  • SQL Intersection Conference, Las Vegas MGM Grand 10-13 November 2014

    - by Paul White
    I am very pleased to announce that I will be speaking at the SQL Intersection conference in Las Vegas again this year. This time around, I am giving a full-day workshop, "Mastering SQL Server Execution Plan Analysis" as well as a two-part session, "Parallel Query Execution" during the main conference. The workshop is a pre-conference event, held on Sunday 9 November (straight after this year's PASS Summit). Being on Sunday gives you the whole Monday off to recover and before the...(read more)

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  • Oracle Expert Live Virtual Seminars - Learn the tricks that only the expert know

    - by rituchhibber
    Oracle University Expert Seminars are exclusive events delivered by top Oracle experts with years of experience in working with Oracle products.         Introduction into ADF & BPM with Markus Grünewald - 11-12 December 2012 ADF/WebCenter 11g Development in Depth with Andrejus Baranovskis - 13-14 December 2012 Beating the Optimizer with Jonathan Lewis - Online - 17 January 2013 RAC Performance Tuning On-Line with Arup Nanda - 25 January 2013 Mastering Oracle Parallel Execution with Randolf Geist - 30 January 2013 Minimize Downtime with Rolling Upgrade using Data Guard with Uwe Hesse - 8 February 2013 For a full list of Oracle Expert Seminars near you or on line click here. Remember that your OPN discount is applied to the standard prices shown on the website.For more information, assistance in booking and to request new dates, contact your local Oracle University Service Desk.

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  • QAliber

    - by csharp-source.net
    QAliber includes 2 projects: a Visual Studio plug-in and Test Builder + Runner as execute framework. Visual Studio plug-in help writing automatic tests over GUI with control browser and record/play capabilities (but not only, since this project incorporate into development solution API testing is easy to do) The Test Builder is a framework for creating a scenario by simply drag and drop of created building blocks. It already provide big repository of test blocks performing most tasks without coding.

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  • Useful utilities - LINQPAD

    - by TATWORTH
    Recently I came across LINQPAD at http://www.linqpad.net/ a free utility by Joseph Alabahari. This is an excellent tool for developing and testing LINQ queries before you incorporate them into your C# programs. If you get stuck as I did at one point recently there is the MSDN Linq forum at http://forums.microsoft.com/MSDN/ShowForum.aspx?siteid=1&ForumID=123 where  you can ask for help.

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