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  • The World of SQL Database Deployment

    - by GGBlogger
    In my early development days, I used Microsoft Access for building databases. It made things easy since I only needed to package the database with the installation package so my clients would have access to it. When we began the development of a new package in Visual Studio .NET I decided to use SQL Server Express. It was free and provided good tools - also free. I thought it was a tremendous idea until it came time to distribute our new software! What a surprise. The nightmare Ah, the choices! Detach the database and have the client reattach it to a newly installed – oh wait. FIRST my new client needs to download and install SQL Server Express with SQL Server Management Studio. That’s not a great thing, but it is one more nightmare step for users who may have other versions of SQL installed. Then the question became – do we detach and reattach or do we do a backup. It was too late (bad planning) to revert to Microsoft Access but we badly needed a simple way to package and distribute both the database AND sample contents. Red Gate to the rescue It took me a while to find an answer but I did find it in a package called SQL Packager sold by a relatively unpublicized company in England called Red Gate. They call their products “ingeniously simple” and I must agree with that description. With SQL Packager you point to the database (more in a minute) you want to distribute. A few mouse clicks and dialogs and you have an executable file that you can ship virtually anywhere and virtually any way which, when run, installs the database on your destination SQL Server instance! It really is that simple. Easier to show than tell Let’s explore a hypothetical case. Let’s say you have a local SQL database of customers and you have decided you want to share it with your subsidiaries or partners. Here is the underlying screen you will see on starting SQL Packager. There are a bunch of possibilities here but I’m going to keep this relatively simple. At this point I simply want to illustrate the simplicity of generating an executable to deliver your database. You will notice that you can set up a new package, edit an existing package or change a bunch of options. Start SQL packager And the following is the default dialog you get on startup. In the next dialog, I’ve selected the Server and Database. I’ve also selected Windows Authentication. Pressing Next causes SQL Packager to run a number of checks and produce a report. Now you’re given a comprehensive list of what is going to be packaged and you’re allowed to change it if you desire. I’ve never made any changes here so I can’t really make any suggestions. The just illustrates the comprehensive nature of so many Red Gate products including this one. Clicking Next gives you still further options. SQL Packager then works its magic and shows you a dialog with the results. Packager then gives you a dialog of the scripts it has generated. The capture above only shows 1 of 4 tabs. Finally pressing Next gives you the option to generate a .NET executable of a C# project. I’ve only generated an executable so I’m not in a position to tell you what the C# project looks like. That may be the subject of further discussions. You can rename the package and tell SQL Packager where to save it. I’ve skipped a lot but this will serve to illustrate the comprehensive (and ingenious) things Red Gate does. All in all, it’s a superb way to distribute populated SQL databases. Oh – we’ll save running the resulting executable for later also but believe me it’s insanely simple.

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  • CI tests to enforce specific development rules - good practice?

    - by KeithS
    The following is all purely hypothetical and any particular portion of it may or may not accurately describe real persons or situations, whether living, dead or just pretending. Let's say I'm a senior dev or architect in charge of a dev team working on a project. This project includes a security library for user authentication/authorization of the application under development. The library must be available for developers to edit; however, I wish to "trust but verify" that coders are not doing things that could compromise the security of the finished system, and because this isn't my only responsibility I want it to be done in an automated way. As one example, let's say I have an interface that represents a user which has been authenticated by the system's security library. The interface exposes basic user info and a list of things the user is authorized to do (so that the client app doesn't have to keep asking the server "can I do this?"), all in an immutable fashion of course. There is only one implementation of this interface in production code, and for the purposes of this post we can say that all appropriate measures have been taken to ensure that this implementation can only be used by the one part of our code that needs to be able to create concretions of the interface. The coders have been instructed that this interface and its implementation are sacrosanct and any changes must go through me. However, those are just words; the security library's source is open for editing by necessity. Any of my devs could decide that this secured, private, hash-checked implementation needs to be public so that they could do X, or alternately they could create their own implementation of this public interface in a different library, exposing the hashing algorithm that provides the secure checksum, in order to do Y. I may not be made aware of these changes so that I can beat the developer over the head for it. An attacker could then find these little nuggets in an unobfuscated library of the compiled product, and exploit it to provide fake users and/or falsely-elevated administrative permissions, bypassing the entire security system. This possibility keeps me awake for a couple of nights, and then I create an automated test that reflectively checks the codebase for types deriving from the interface, and fails if it finds any that are not exactly what and where I expect them to be. I compile this test into a project under a separate folder of the VCS that only I have rights to commit to, have CI compile it as an external library of the main project, and set it up to run as part of the CI test suite for user commits. Now, I have an automated test under my complete control that will tell me (and everyone else) if the number of implementations increases without my involvement, or an implementation that I did know about has anything new added or has its modifiers or those of its members changed. I can then investigate further, and regain the opportunity to beat developers over the head as necessary. Is this considered "reasonable" to want to do in situations like this? Am I going to be seen in a negative light for going behind my devs' backs to ensure they aren't doing something they shouldn't?

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  • 4 Key Ingredients for the Cloud

    - by Kellsey Ruppel
    It's a short week here with the US Thanksgiving Holiday. So, before we put on our stretch pants and get ready to belly up to the dinner table for turkey, stuffing and mashed potatoes, let's spend a little time this week talking about the Cloud (kind of like the feathery whipped goodness that tops the infamous Thanksgiving pumpkin pie!) But before we dive into the Cloud, let's do a side by side comparison of the key ingredients for each. Cloud Whipped Cream  Application Integration  1 cup heavy cream  Security  1/4 cup sugar  Virtual I/O  1 teaspoon vanilla  Storage  Chilled Bowl It’s no secret that millions of people are connected to the Internet. And it also probably doesn’t come as a surprise that a lot of those people are connected on social networking sites.  Social networks have become an excellent platform for sharing and communication that reflects real world relationships and they play a major part in the everyday lives of many people. Facebook, Twitter, Pinterest, LinkedIn, Google+ and hundreds of others have transformed the way we interact and communicate with one another.Social networks are becoming more than just an online gathering of friends. They are becoming a destination for ideation, e-commerce, and marketing. But it doesn’t just stop there. Some organizations are utilizing social networks internally, integrated with their business applications and processes and the possibility of social media and cloud integration is compelling. Forrester alone estimates enterprise cloud computing to grow to over $240 billion by 2020. It’s hard to find any current IT project today that is NOT considering cloud-based deployments. Security and quality of service concerns are no longer at the forefront; rather, it’s about focusing on the right mix of capabilities for the business. Cloud vs. On-Premise? Policies & governance models? Social in the cloud? Cloud’s increasing sophistication, security in applications, mobility, transaction processing and social capabilities make it an attractive way to manage information. And Oracle offers all of this through the Oracle Cloud and Oracle Social Network. Oracle Social Network is a secure private network that provides a broad range of social tools designed to capture and preserve information flowing between people, enterprise applications, and business processes. By connecting you with your most critical applications, Oracle Social Network provides contextual, real-time communication within and across enterprises. With Oracle Social Network, you and your teams have the tools you need to collaborate quickly and efficiently, while leveraging the organization’s collective expertise to make informed decisions and drive business forward. Oracle Social Network is available as part of a portfolio of application and platform services within the Oracle Cloud. Oracle Cloud offers self-service business applications delivered on an integrated development and deployment platform with tools to rapidly extend and create new services. Oracle Social Network is pre-integrated with the Fusion CRM Cloud Service and the Fusion HCM Cloud Service within the Oracle Cloud. If you are looking for something to watch as you veg on the couch in a post-turkey dinner hangover, you might consider watching these how-to videos! And yes, it is perfectly ok to have that 2nd piece of pie

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  • A .NET Developers day with the iPad.

    - by mbcrump
    The Apple iPad is currently getting a lot of buzz because of the app store, the book store and of course iTunes. I had the chance to play with one and this is what I have learned about the device. Let’s get this out of the way first, the iPad is awesome. It is the device for media consumption and casual web browsing. But how does it measure up to those of us with .NET on our brains all days. Let’s find out… Main Screen – you can customize everything on this page. I guess I should replace that image with a C# or VS logo. Its pretty standard stuff if you have an iPhone.   Programming Books If you have a subscription to Safari Books Online, then you are in luck, its very easy to read the books on the iPad. Just fire up Safari web browser and goto the Safari Books Online. The biggest benefit that I can see with the iPad is the ability to read books wherever and not have to worry about purchasing books that I already have the .PDF for. Below is a sample from Code Complete 2nd Edition. Below is a PDF of the ECMA-334 C# Language Specification. As you can see its very readable and you should have no problem reading actual code.   Example of Code shown below: It is however easier to read the PDF and store them with a 3rd party PDF reader. I have seen several for .99 cents or less. You can however switch the screen to vertical to get more viewing space as shown below: I was disappointed with the iBooks application. I could not find a single .NET programming book anywhere. I was able to download the excellent sci-fi book “A memory of Wind” for free though. If I just overlooked them, then please email me with the names and titles. I couldn’t even find a technology category in the categories list. Web Surfing – Technical Sites Below is an example of my site in Safari. The code is very readable and the experience was identical to viewing it in Firefox. I tried multiple programming site and the pages looked great except those that used flash and of course it did not display on those pages.   News Apps - Technical Content The standard NY Times and USA Today looked great, but the Technical Content was lacking. It would probably be better to use Google Reader for online technical news.     YouTube Videos – Technical Content  Since its YouTube, we already know that a lot of technical content exist and it plays great on the iPad. I watched several programming videos and could clearly see the code being written. Taking Technical Notes The iPad comes with a great notepad for taking notes. I found that it was easy to take notes regarding projects that I am currently working on.   Calendar The calendar that ships with the iPad is great for organizing. You can setup exchange server or manually enter the information. Pretty standard stuff.    Random Applications that I like: TweetDeck.   and Adobe Ideas. Adobe Ideas is kinda like SketchFlow except you use your finger to mock up the sketches.  Don’t forget that the iPad is great for any type of podcasting. That pretty much sums it up, I would definitely recommend this device as it will only get better. I believe the iOS4 comes out on the 24th and the iPad will only get more and more apps. You could save a few bucks by waiting for the 2nd generation, but that’s a call that only you can make.

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  • Asynchrony in C# 5 (Part II)

    - by javarg
    This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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  • how to keep display tick rate steady when using continuous collision detection?

    - by nas Ns
    (I've just found about this forum). I hope it is ok to repost my question again here. I posted this question at stackoverflow, but it looks like I might get better help here. Here is the question: I've implemented basic particles motion simulation with continuous collision detection. But there is small issue in display. Assume simple case of circles moving inside square. All elastic collisions. no firction. All motion is constant speed. No forces are involved, no gravity. So when a particle is moving, it is always moving at constant speed (in between collisions) What I do now is this: Let the simulation time step be 1 second (for example). This is the time step simulation is advanced before displaying the new state (unless there is a collision sooner than this). At start of each time step, time for the next collision between any particles or a particle with a wall is determined. Call this the TOC time; let’s say TOC was .5 seconds in this case. Since TOC is smaller than the standard time step, then the system is moved by TOC and the new system is displayed so that the new display shows any collisions as just taking place (say 2 circles just touched each other’s, or a circle just touched a wall) Next, the collision(s) are resolved (i.e. speeds updated, changed directions etc..). A new step is started. The same thing happens. Now assume there is no collision detected within the next 1 second (those 2 circles above will not be in collision any more, even though they are still touching, due to their speeds showing they are moving apart now), Hence, simulation time is advanced now by the full one second, the standard time step, and particles are moved on the screen using 1 second simulation time and new display is shown. You see what has just happened: One frame ran for .5 seconds, but the next frame runs for 1 second, may be the 3rd frame is displayed after 2 seconds, may be the 4th frame is displayed after 2.8 seconds (because TOC was .8 seconds then) and so on. What happens is that the motion of a particle on the screen appears to speed up or slow down, even though it is moving at constant speed and was not even involved in a collision. i.e. Looking at one particle on its own, I see it suddenly speeding up or slowing down, becuase another particle had hit a wall. This is because the display tick is not uniform. i.e. the frame rate update is changing, giving the false illusion that a particle is moving at non-constant speed while in fact it is moving at constant speed. The motion on the screen is not smooth, since the screen is not updating at constant rate. I am not able to figure how to fix this. If I want to show 2 particles at the moment of the collision, I must draw the screen at different times. Drawing the screen always at the same tick interval, results in seeing 2 particles before the collision, and then after the collision, and not just when they colliding, which looked bad when I tried it. So, how do real games handle this issue? How to display things in order to show collisions when it happen, yet keep the display tick constant? These 2 requirements seem to contradict each other’s.

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  • Dependency Injection Introduction

    - by MarkPearl
    I recently was going over a great book called “Dependency Injection in .Net” by Mark Seeman. So far I have really enjoyed the book and would recommend anyone looking to get into DI to give it a read. Today I thought I would blog about the first example Mark gives in his book to illustrate some of the benefits that DI provides. The ones he lists are Late binding Extensibility Parallel Development Maintainability Testability To illustrate some of these benefits he gives a HelloWorld example using DI that illustrates some of the basic principles. It goes something like this… class Program { static void Main(string[] args) { var writer = new ConsoleMessageWriter(); var salutation = new Salutation(writer); salutation.Exclaim(); Console.ReadLine(); } } public interface IMessageWriter { void Write(string message); } public class ConsoleMessageWriter : IMessageWriter { public void Write(string message) { Console.WriteLine(message); } } public class Salutation { private readonly IMessageWriter _writer; public Salutation(IMessageWriter writer) { _writer = writer; } public void Exclaim() { _writer.Write("Hello World"); } }   If you had asked me a few years ago if I had thought this was a good approach to solving the HelloWorld problem I would have resounded “No”. How could the above be better than the following…. class Program { static void Main(string[] args) { Console.WriteLine("Hello World"); Console.ReadLine(); } }  Today, my mind-set has changed because of the pain of past programs. So often we can look at a small snippet of code and make judgements when we need to keep in mind that we will most probably be implementing these patterns in projects with hundreds of thousands of lines of code and in projects that we have tests that we don’t want to break and that’s where the first solution outshines the latter. Let’s see if the first example achieves some of the outcomes that were listed as benefits of DI. Could I test the first solution easily? Yes… We could write something like the following using NUnit and RhinoMocks… [TestFixture] public class SalutationTests { [Test] public void ExclaimWillWriteCorrectMessageToMessageWriter() { var writerMock = MockRepository.GenerateMock<IMessageWriter>(); var sut = new Salutation(writerMock); sut.Exclaim(); writerMock.AssertWasCalled(x => x.Write("Hello World")); } }   This would test the existing code fine. Let’s say we then wanted to extend the original solution so that we had a secure message writer. We could write a class like the following… public class SecureMessageWriter : IMessageWriter { private readonly IMessageWriter _writer; private readonly string _secretPassword; public SecureMessageWriter(IMessageWriter writer, string secretPassword) { _writer = writer; _secretPassword = secretPassword; } public void Write(string message) { if (_secretPassword == "Mark") { _writer.Write(message); } else { _writer.Write("Unauthenticated"); } } }   And then extend our implementation of the program as follows… class Program { static void Main(string[] args) { var writer = new SecureMessageWriter(new ConsoleMessageWriter(), "Mark"); var salutation = new Salutation(writer); salutation.Exclaim(); Console.ReadLine(); } }   Our application has now been successfully extended and yet we did very little code change. In addition, our existing tests did not break and we would just need add tests for the extended functionality. Would this approach allow parallel development? Well, I am in two camps on parallel development but with some planning ahead of time it would allow for it as you would simply need to decide on the interface signature and could then have teams develop different sections programming to that interface. So,this was really just a quick intro to some of the basic concepts of DI that Mark introduces very successfully in his book. I am hoping to blog about this further as I continue through the book to list some of the more complex implementations of containers.

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  • Does *every* project benefit from written specifications?

    - by nikie
    I know this is holy war territory, so please read the question to the end before answering. There are many cases where written specifications make a lot of sense. For example, if you're a contractor and you want to get paid, you need written specs. If you're working in a team with 20 persons, you need written specs. If you're writing a programming language compiler or interpreter (and it's not perl), you'll usually write a formal specification. I don't doubt that there are many more cases where written specifications are a really good idea. I just think that there are cases where there's so little benefit in written specs, that it doesn't outweigh the costs of writing and maintaining them. EDIT: The close votes say that "it is difficult to say what is asked here", so let me clarify: The usefulness of written, detailed specifications is often claimed like a dogma. (If you want examples, look at the comments.) But I don't see the use of them for the kind of development I'm doing. So what is asked here is: How would written specifications help me? Background information: I work for a small company that's developing vertical market software. If our product is easier to use and has better performance than the competition, it sells. If it's harder to use, even if it behaves 100% as the specification says, it doesn't sell. So there are no "external forces" for having written specs. The advantage would have to be somewhere in the development process. Now, I can see how frozen specifications would make a developer's life easier. But we'll never have frozen specs. If we see in the middle of development that feature X is not intuitive to use the way it's specified, then we can only choose between changing the specification or developing a product that won't sell. You'll probably ask by now: How do you know when you're done? Well, we're continually improving our product. The competition does the same. So (hopefully) we're never done. We keep improving the software, and when we reach a point when the benefits of the improvements we've added since the last release outweigh the costs of an update, we create a new release that is then tested, localized, documented and deployed. This also means that there's rarely any schedule pressure. Nobody has to do overtime to make a deadline. If the feature isn't done by the time we want to release the next version, it'll simply go into the next version. The next question might be: How do your developers know what they're supposed to implement? The answer is: They have a lot of domain knowledge. They know the customers business well enough, so a high-level description of the feature (or even just the problem that the customer needs solved) is enough to implement it. If it's not clear, the developer creates a few fake screens to get feedback from marketing/management or customers, but this is nowhere near the level of detail of actual specifications. This might be inefficient for larger teams, but for a small team with low turnover it works quite well. It has the additional benefit that the developer in question often comes up with a better solution than the person writing the specs might have. This question is already getting very long, but let me address one last point: Testing. Like I said in the beginning, if our software behaves 100% like the spec says, it still can be crap. In fact, if it's so unintuitive that you need a spec to know how to test it, it probably is crap. It makes sense to have fixed, written tests for some core functionality and for regression bugs, but again, this is nowhere near a full written spec of how the software should behave when. The main test is: hand the software to a user who doesn't know it yet and tell him to use the new feature X. If she can figure out how to use it and it works, it works.

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  • Drive

    - by erikanollwebb
    Picking up where we left off, let's summarize.  People have both intrinsic motivation and extrinsic motivation, and whether reward works depends a bit on what you are rewarding.  Rewards don't decreased intrinsic motivation provided you know what you are getting and why, and when you reward high performance.  But as anyone who has watched the great animation of Dan Pink's TED talk knows, even that doesn't tell the whole story.  Although people may not be less intrinsically motivated by rewards, the impact of rewards on actual performance is a really odd questions.  Larger rewards don't necessarily lead to better performance and in fact, some times lead to worse performance.  Pink argues that people are driven and engaged when they have autonomy, mastery and purpose.  If they can self-direct and can be good at what they do and have a sense of purpose for what they are doing, they show the highest engagement.   (Personally, I would add progress to the list.  My experience is that if you have autonomy, mastery and a sense of purpose but don't get a feeling that you are making any progress day to day, your level of engagement will drop rapidly.) So Pink is arguing if we could set up work so that people have a sense of purpose in what they do, have some autonomy and the ability to build mastery, you'll have better companies.  And that's probably true in a lot of ways, but there's a problem.  Sometimes, you have things you need to do but maybe you don't really want to do.  Or that you don't really see the point of.  Or that doesn't have a lot of value to you at the end of the day.  Then what does a company do?  Let me give you an example.  I've worked on some customer relationship management (CRM) tools over the years and done user research with sales people to try and understand their world.  And there's a funny thing about sales tools in CRM.  Sometimes what the company wants a sales person to do is at odds with what a sales person thinks is useful to them.  For example, companies would like to know who a sales person talked to at the company and the person level.  They'd like to know what they talked about, when, and whether the deals closed.  Those metrics would help you build a better sales force and understand what works and what does not.  But sales people see that as busy work that doesn't add any value to their ability to sell.  So you have a sales person who has a lot of autonomy, they like to do things that improve their ability to sell and they usually feel a sense of purpose--the group is trying to make a quota!  That quota will help the company succeed!  But then you have tasks that they don't think fit into that equation.  The company would like to know more about what makes them successful and get metrics on what they do and frankly, have a record of what they do in case they leave, but the sales person thinks it's a waste of time to put all that information into a sales application. They have drive, just not for all the things the company would like.   You could punish them for not entering the information, or you could try to reward them for doing it, but you still have an imperfect model of engagement.  Ideally, you'd like them to want to do it.  If they want to do it, if they are motivated to do it, then the company wins.  If *something* about it is rewarding to them, then they are more engaged and more likely to do it.  So the question becomes, how do you create that interest to do something?

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  • Setting up your project

    - by ssoolsma
    Before any coding we first make sure that the project is setup correctly. (Please note, that this blog is all about how I do it, and incase i forget, i can return here and read how i used to do it. Maybe you come up with some idea’s for yourself too.) In these series we will create a minigolf scoring cart. Please note that we eventually create a fully functional application which you cannot use unless you pay me alot of money! (And i mean alot!)   1. Download and install the appropriate tools. Download the following: - TestDriven.Net (free version on the bottom of the download page) - nUnit TestDriven is a visual studio plugin for many unittest frameworks, which allows you to run  / test code very easily with a right click –> run test. nUnit is the test framework of choice, it works seamless with TestDriven.   2. Create your project Fire up visual studio and create your DataAccess project:  MidgetWidget.DataAccess is it’s name. (I choose MidgetWidget as name for the solution). Also, make sure that the MidgetWidget.DataAccess project is a c# ClassLibary Hit OK to create the solution. (in the above example the checkbox Create directory for solution is checked, because i’m pointing the location to the root of c:\development where i want MidgetWidget to be created.   3. Setup the database. You should have thought about a database when you reach this point. Let’s assume that you’ve created a database as followed: Table name: LoginKey Fields: Id (PK), KeyName (uniqueidentifier), StartDate (datetime), EndDate (datetime) Table name:  Party Fields: Id (PK), Key (uniqueidentifier, Created (datetime) Table name:  Person Fields: Id(PK),  PartyId (int), Name (varchar) Tablename: Score Fields: Id (PK), Trackid (int), PersonId (int), Strokes (int) Tablename: Track Fields: Id (PK), Name (varchar) A few things to take note about the database setup. I’ve singularized all tablenames (not “Persons“ but “Person”. This is because in a few minutes, when this is in our code, we refer to the database objects as single rows. We retrieve a single Person not a single “Persons” from the database.   4. Create the entity framework In your solution tree create a new folder and call it “DataModel”. Inside this folder: Add new item –> and choose ADO.NET Entity Data Model. Name it “Entities.edmx” and hit  “Add”. Once the edmx is added, open it (double click) and right click the white area and choose “Update model from database…". Now, point it to your database (i include sensitive data in the connectionstring) and select all the tables. After that hit “Finish” and let the entity framework do it’s code generation. Et Voila, after a few seconds you have set up your entity model. Next post we will start building the data-access! I’m off to the beach.

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  • Broken Views

    - by Ajarn Mark Caldwell
    “SELECT *” isn’t just hazardous to performance, it can actually return blatantly wrong information. There are a number of blog posts and articles out there that actively discourage the use of the SELECT * FROM …syntax.  The two most common explanations that I have seen are: Performance:  The SELECT * syntax will return every column in the table, but frequently you really only need a few of the columns, and so by using SELECT * your are retrieving large volumes of data that you don’t need, but the system has to process, marshal across tiers, and so on.  It would be much more efficient to only select the specific columns that you need. Future-proof:  If you are taking other shortcuts in your code, along with using SELECT *, you are setting yourself up for trouble down the road when enhancements are made to the system.  For example, if you use SELECT * to return results from a table into a DataTable in .NET, and then reference columns positionally (e.g. myDataRow[5]) you could end up with bad data if someone happens to add a column into position 3 and skewing all the remaining columns’ ordinal position.  Or if you use INSERT…SELECT * then you will likely run into errors when a new column is added to the source table in any position. And if you use SELECT * in the definition of a view, you will run into a variation of the future-proof problem mentioned above.  One of the guys on my team, Mike Byther, ran across this in a project we were doing, but fortunately he caught it while we were still in development.  I asked him to put together a test to prove that this was related to the use of SELECT * and not some other anomaly.  I’ll walk you through the test script so you can see for yourself what happens. We are going to create a table and two views that are based on that table, one of them uses SELECT * and the other explicitly lists the column names.  The script to create these objects is listed below. IF OBJECT_ID('testtab') IS NOT NULL DROP TABLE testtabgoIF OBJECT_ID('testtab_vw') IS NOT NULL DROP VIEW testtab_vwgo IF OBJECT_ID('testtab_vw_named') IS NOT NULL DROP VIEW testtab_vw_namedgo CREATE TABLE testtab (col1 NVARCHAR(5) null, col2 NVARCHAR(5) null)INSERT INTO testtab(col1, col2)VALUES ('A','B'), ('A','B')GOCREATE VIEW testtab_vw AS SELECT * FROM testtabGOCREATE VIEW testtab_vw_named AS SELECT col1, col2 FROM testtabgo Now, to prove that the two views currently return equivalent results, select from them. SELECT 'star', col1, col2 FROM testtab_vwSELECT 'named', col1, col2 FROM testtab_vw_named OK, so far, so good.  Now, what happens if someone makes a change to the definition of the underlying table, and that change results in a new column being inserted between the two existing columns?  (Side note, I normally prefer to append new columns to the end of the table definition, but some people like to keep their columns alphabetized, and for clarity for later people reviewing the schema, it may make sense to group certain columns together.  Whatever the reason, it sometimes happens, and you need to protect yourself and your code from the repercussions.) DROP TABLE testtabgoCREATE TABLE testtab (col1 NVARCHAR(5) null, col3 NVARCHAR(5) NULL, col2 NVARCHAR(5) null)INSERT INTO testtab(col1, col3, col2)VALUES ('A','C','B'), ('A','C','B')goSELECT 'star', col1, col2 FROM testtab_vwSELECT 'named', col1, col2 FROM testtab_vw_named I would have expected that the view using SELECT * in its definition would essentially pass-through the column name and still retrieve the correct data, but that is not what happens.  When you run our two select statements again, you see that the View that is based on SELECT * actually retrieves the data based on the ordinal position of the columns at the time that the view was created.  Sure, one work-around is to recreate the View, but you can’t really count on other developers to know the dependencies you have built-in, and they won’t necessarily recreate the view when they refactor the table. I am sure that there are reasons and justifications for why Views behave this way, but I find it particularly disturbing that you can have code asking for col2, but actually be receiving data from col3.  By the way, for the record, this entire scenario and accompanying test script apply to SQL Server 2008 R2 with Service Pack 1. So, let the developer beware…know what assumptions are in effect around your code, and keep on discouraging people from using SELECT * syntax in anything but the simplest of ad-hoc queries. And of course, let’s clean up after ourselves.  To eliminate the database objects created during this test, run the following commands. DROP TABLE testtabDROP VIEW testtab_vwDROP VIEW testtab_vw_named

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  • Selective Suppression of Log Messages

    - by Duncan Mills
    Those of you who regularly read this blog will probably have noticed that I have a strange predilection for logging related topics, so why break this habit I ask?  Anyway here's an issue which came up recently that I thought was a good one to mention in a brief post.  The scenario really applies to production applications where you are seeing entries in the log files which are harmless, you know why they are there and are happy to ignore them, but at the same time you either can't or don't want to risk changing the deployed code to "fix" it to remove the underlying cause. (I'm not judging here). The good news is that the logging mechanism provides a filtering capability which can be applied to a particular logger to selectively "let a message through" or suppress it. This is the technique outlined below. First Create Your Filter  You create a logging filter by implementing the java.util.logging.Filter interface. This is a very simple interface and basically defines one method isLoggable() which simply has to return a boolean value. A return of false will suppress that particular log message and not pass it onto the handler. The method is passed the log record of type java.util.logging.LogRecord which provides you with access to everything you need to decide if you want to let this log message pass through or not, for example  getLoggerName(), getMessage() and so on. So an example implementation might look like this if we wanted to filter out all the log messages that start with the string "DEBUG" when the logging level is not set to FINEST:  public class MyLoggingFilter implements Filter {     public boolean isLoggable(LogRecord record) {         if ( !record.getLevel().equals(Level.FINEST) && record.getMessage().startsWith("DEBUG")){          return false;            }         return true;     } } Deploying   This code needs to be put into a JAR and added to your WebLogic classpath.  It's too late to load it as part of an application, so instead you need to put the JAR file into the WebLogic classpath using a mechanism such as the PRE_CLASSPATH setting in your domain setDomainEnv script. Then restart WLS of course. Using The final piece if to actually assign the filter.  The simplest way to do this is to add the filter attribute to the logger definition in the logging.xml file. For example, you may choose to define a logger for a specific class that is raising these messages and only apply the filter in that case.  <logger name="some.vendor.adf.ClassICantChange"         filter="oracle.demo.MyLoggingFilter"/> You can also apply the filter using WLST if you want a more script-y solution.

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  • Best way to process a queue in C# (PDF treatment)

    - by Bartdude
    First of all let me expose what I would like to do : I already dispose of a long-time running webapp developed in ASP.NET (C#) 2.0. In this app, users can upload standard PDF files (text+pics). The app is running in production on a Windows Server 2003 and has a dedicated database server (SQL server 2008) also running Windows Server 2003. I myself am a quite experienced web developer, but never actually programmed anything non-web (or at least nothing serious). I plan on adding a functionality to the webapp for which I would need a jpg snapshot of each page of the PDF. Creating these "thumbnails" isn't the big deal as such, I already do it inside my webapp using ghostscript. I've only done it on 1 page documents for now though, and the new functionality will need to process bigger documents. In order for this process to be transparent aswell for the admins as the final users, I would like to implement some kind of queue to delay the processing of the thumbnails. There again, no problem to create the queue, it will consist of records in a table, with enough info to find the pdf document back. Then I will need to process this queue, and that's were my interrogations start. Obviously the best solution to process it isn't an ASP script or so, so I will have to get out of my known environment. No problem, but I have no idea which direction to go. Therefore, a few questions : What should I develop ? I presumably need something that is "standby" on the server, runs when needed, then returns to idle state until further notice.Should I be looking into Windows service ? Is there another more appropriate type of project ? Depending on the first answer, what will be the approach ? Should I have somehow SQL server "tell" the program/service/... to process the queue, or should I have that program/service/... periodically check the state of the queue and treat new items. In both case, which functionality can I use ? we're not talking about hundreds of PDF a day (max 50 maybe), I can totally afford to treat the queue 1 item at a time. Can you confirm I don't have to look much further on threads and so ? (I found a lot of answers talking about threads in queue treatment, but it looks quite overkill for my needs) Maybe linked to the previous question : what about concurrent call to the program, whatever it is ? Let's suppose it is currently running, and a new record comes in the queue, what should be the behaviour ? I don't need much detailed answers and would already be happy with answers like "You can do the processing with a service, and yes it's possible to have sqlserver on machine A trigger a service start on machine B" or "You have to develop xxx and then use the scheduler to run it every xxx minutes". I don't mind reading articles and so, but I can hardly afford to spend too much time learning stuff to finally realize I went the wrong way for this project, so basically I'm trying to narrow down the scope of matters I need to investigate. Thanks for reading me, I hope I'll find some helping hands on here :-)

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  • Why is 0 false?

    - by Morwenn
    This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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  • Agile Development

    - by James Oloo Onyango
    Alot of literature has and is being written about agile developement and its surrounding philosophies. In my quest to find the best way to express the importance of agile methodologies, i have found Robert C. Martin's "A Satire Of Two Companies" to be both the most concise and thorough! Enjoy the read! Rufus Inc Project Kick Off Your name is Bob. The date is January 3, 2001, and your head still aches from the recent millennial revelry. You are sitting in a conference room with several managers and a group of your peers. You are a project team leader. Your boss is there, and he has brought along all of his team leaders. His boss called the meeting. "We have a new project to develop," says your boss's boss. Call him BB. The points in his hair are so long that they scrape the ceiling. Your boss's points are just starting to grow, but he eagerly awaits the day when he can leave Brylcream stains on the acoustic tiles. BB describes the essence of the new market they have identified and the product they want to develop to exploit this market. "We must have this new project up and working by fourth quarter October 1," BB demands. "Nothing is of higher priority, so we are cancelling your current project." The reaction in the room is stunned silence. Months of work are simply going to be thrown away. Slowly, a murmur of objection begins to circulate around the conference table.   His points give off an evil green glow as BB meets the eyes of everyone in the room. One by one, that insidious stare reduces each attendee to quivering lumps of protoplasm. It is clear that he will brook no discussion on this matter. Once silence has been restored, BB says, "We need to begin immediately. How long will it take you to do the analysis?" You raise your hand. Your boss tries to stop you, but his spitwad misses you and you are unaware of his efforts.   "Sir, we can't tell you how long the analysis will take until we have some requirements." "The requirements document won't be ready for 3 or 4 weeks," BB says, his points vibrating with frustration. "So, pretend that you have the requirements in front of you now. How long will you require for analysis?" No one breathes. Everyone looks around to see whether anyone has some idea. "If analysis goes beyond April 1, we have a problem. Can you finish the analysis by then?" Your boss visibly gathers his courage: "We'll find a way, sir!" His points grow 3 mm, and your headache increases by two Tylenol. "Good." BB smiles. "Now, how long will it take to do the design?" "Sir," you say. Your boss visibly pales. He is clearly worried that his 3 mms are at risk. "Without an analysis, it will not be possible to tell you how long design will take." BB's expression shifts beyond austere.   "PRETEND you have the analysis already!" he says, while fixing you with his vacant, beady little eyes. "How long will it take you to do the design?" Two Tylenol are not going to cut it. Your boss, in a desperate attempt to save his new growth, babbles: "Well, sir, with only six months left to complete the project, design had better take no longer than 3 months."   "I'm glad you agree, Smithers!" BB says, beaming. Your boss relaxes. He knows his points are secure. After a while, he starts lightly humming the Brylcream jingle. BB continues, "So, analysis will be complete by April 1, design will be complete by July 1, and that gives you 3 months to implement the project. This meeting is an example of how well our new consensus and empowerment policies are working. Now, get out there and start working. I'll expect to see TQM plans and QIT assignments on my desk by next week. Oh, and don't forget that your crossfunctional team meetings and reports will be needed for next month's quality audit." "Forget the Tylenol," you think to yourself as you return to your cubicle. "I need bourbon."   Visibly excited, your boss comes over to you and says, "Gosh, what a great meeting. I think we're really going to do some world shaking with this project." You nod in agreement, too disgusted to do anything else. "Oh," your boss continues, "I almost forgot." He hands you a 30-page document. "Remember that the SEI is coming to do an evaluation next week. This is the evaluation guide. You need to read through it, memorize it, and then shred it. It tells you how to answer any questions that the SEI auditors ask you. It also tells you what parts of the building you are allowed to take them to and what parts to avoid. We are determined to be a CMM level 3 organization by June!"   You and your peers start working on the analysis of the new project. This is difficult because you have no requirements. But from the 10-minute introduction given by BB on that fateful morning, you have some idea of what the product is supposed to do.   Corporate process demands that you begin by creating a use case document. You and your team begin enumerating use cases and drawing oval and stick diagrams. Philosophical debates break out among the team members. There is disagreement as to whether certain use cases should be connected with <<extends>> or <<includes>> relationships. Competing models are created, but nobody knows how to evaluate them. The debate continues, effectively paralyzing progress.   After a week, somebody finds the iceberg.com Web site, which recommends disposing entirely of <<extends>> and <<includes>> and replacing them with <<precedes>> and <<uses>>. The documents on this Web site, authored by Don Sengroiux, describes a method known as stalwart-analysis, which claims to be a step-by-step method for translating use cases into design diagrams. More competing use case models are created using this new scheme, but again, people can't agree on how to evaluate them. The thrashing continues. More and more, the use case meetings are driven by emotion rather than by reason. If it weren't for the fact that you don't have requirements, you'd be pretty upset by the lack of progress you are making. The requirements document arrives on February 15. And then again on February 20, 25, and every week thereafter. Each new version contradicts the previous one. Clearly, the marketing folks who are writing the requirements, empowered though they might be, are not finding consensus.   At the same time, several new competing use case templates have been proposed by the various team members. Each template presents its own particularly creative way of delaying progress. The debates rage on. On March 1, Prudence Putrigence, the process proctor, succeeds in integrating all the competing use case forms and templates into a single, all-encompassing form. Just the blank form is 15 pages long. She has managed to include every field that appeared on all the competing templates. She also presents a 159- page document describing how to fill out the use case form. All current use cases must be rewritten according to the new standard.   You marvel to yourself that it now requires 15 pages of fill-in-the-blank and essay questions to answer the question: What should the system do when the user presses Return? The corporate process (authored by L. E. Ott, famed author of "Holistic Analysis: A Progressive Dialectic for Software Engineers") insists that you discover all primary use cases, 87 percent of all secondary use cases, and 36.274 percent of all tertiary use cases before you can complete analysis and enter the design phase. You have no idea what a tertiary use case is. So in an attempt to meet this requirement, you try to get your use case document reviewed by the marketing department, which you hope will know what a tertiary use case is.   Unfortunately, the marketing folks are too busy with sales support to talk to you. Indeed, since the project started, you have not been able to get a single meeting with marketing, which has provided a never-ending stream of changing and contradictory requirements documents.   While one team has been spinning endlessly on the use case document, another team has been working out the domain model. Endless variations of UML documents are pouring out of this team. Every week, the model is reworked.   The team members can't decide whether to use <<interfaces>> or <<types>> in the model. A huge disagreement has been raging on the proper syntax and application of OCL. Others on the team just got back from a 5-day class on catabolism, and have been producing incredibly detailed and arcane diagrams that nobody else can fathom.   On March 27, with one week to go before analysis is to be complete, you have produced a sea of documents and diagrams but are no closer to a cogent analysis of the problem than you were on January 3. **** And then, a miracle happens.   **** On Saturday, April 1, you check your e-mail from home. You see a memo from your boss to BB. It states unequivocally that you are done with the analysis! You phone your boss and complain. "How could you have told BB that we were done with the analysis?" "Have you looked at a calendar lately?" he responds. "It's April 1!" The irony of that date does not escape you. "But we have so much more to think about. So much more to analyze! We haven't even decided whether to use <<extends>> or <<precedes>>!" "Where is your evidence that you are not done?" inquires your boss, impatiently. "Whaaa . . . ." But he cuts you off. "Analysis can go on forever; it has to be stopped at some point. And since this is the date it was scheduled to stop, it has been stopped. Now, on Monday, I want you to gather up all existing analysis materials and put them into a public folder. Release that folder to Prudence so that she can log it in the CM system by Monday afternoon. Then get busy and start designing."   As you hang up the phone, you begin to consider the benefits of keeping a bottle of bourbon in your bottom desk drawer. They threw a party to celebrate the on-time completion of the analysis phase. BB gave a colon-stirring speech on empowerment. And your boss, another 3 mm taller, congratulated his team on the incredible show of unity and teamwork. Finally, the CIO takes the stage to tell everyone that the SEI audit went very well and to thank everyone for studying and shredding the evaluation guides that were passed out. Level 3 now seems assured and will be awarded by June. (Scuttlebutt has it that managers at the level of BB and above are to receive significant bonuses once the SEI awards level 3.)   As the weeks flow by, you and your team work on the design of the system. Of course, you find that the analysis that the design is supposedly based on is flawedno, useless; no, worse than useless. But when you tell your boss that you need to go back and work some more on the analysis to shore up its weaker sections, he simply states, "The analysis phase is over. The only allowable activity is design. Now get back to it."   So, you and your team hack the design as best you can, unsure of whether the requirements have been properly analyzed. Of course, it really doesn't matter much, since the requirements document is still thrashing with weekly revisions, and the marketing department still refuses to meet with you.     The design is a nightmare. Your boss recently misread a book named The Finish Line in which the author, Mark DeThomaso, blithely suggested that design documents should be taken down to code-level detail. "If we are going to be working at that level of detail," you ask, "why don't we simply write the code instead?" "Because then you wouldn't be designing, of course. And the only allowable activity in the design phase is design!" "Besides," he continues, "we have just purchased a companywide license for Dandelion! This tool enables 'Round the Horn Engineering!' You are to transfer all design diagrams into this tool. It will automatically generate our code for us! It will also keep the design diagrams in sync with the code!" Your boss hands you a brightly colored shrinkwrapped box containing the Dandelion distribution. You accept it numbly and shuffle off to your cubicle. Twelve hours, eight crashes, one disk reformatting, and eight shots of 151 later, you finally have the tool installed on your server. You consider the week your team will lose while attending Dandelion training. Then you smile and think, "Any week I'm not here is a good week." Design diagram after design diagram is created by your team. Dandelion makes it very difficult to draw these diagrams. There are dozens and dozens of deeply nested dialog boxes with funny text fields and check boxes that must all be filled in correctly. And then there's the problem of moving classes between packages. At first, these diagram are driven from the use cases. But the requirements are changing so often that the use cases rapidly become meaningless. Debates rage about whether VISITOR or DECORATOR design patterns should be used. One developer refuses to use VISITOR in any form, claiming that it's not a properly object-oriented construct. Someone refuses to use multiple inheritance, since it is the spawn of the devil. Review meetings rapidly degenerate into debates about the meaning of object orientation, the definition of analysis versus design, or when to use aggregation versus association. Midway through the design cycle, the marketing folks announce that they have rethought the focus of the system. Their new requirements document is completely restructured. They have eliminated several major feature areas and replaced them with feature areas that they anticipate customer surveys will show to be more appropriate. You tell your boss that these changes mean that you need to reanalyze and redesign much of the system. But he says, "The analysis phase is system. But he says, "The analysis phase is over. The only allowable activity is design. Now get back to it."   You suggest that it might be better to create a simple prototype to show to the marketing folks and even some potential customers. But your boss says, "The analysis phase is over. The only allowable activity is design. Now get back to it." Hack, hack, hack, hack. You try to create some kind of a design document that might reflect the new requirements documents. However, the revolution of the requirements has not caused them to stop thrashing. Indeed, if anything, the wild oscillations of the requirements document have only increased in frequency and amplitude.   You slog your way through them.   On June 15, the Dandelion database gets corrupted. Apparently, the corruption has been progressive. Small errors in the DB accumulated over the months into bigger and bigger errors. Eventually, the CASE tool just stopped working. Of course, the slowly encroaching corruption is present on all the backups. Calls to the Dandelion technical support line go unanswered for several days. Finally, you receive a brief e-mail from Dandelion, informing you that this is a known problem and that the solution is to purchase the new version, which they promise will be ready some time next quarter, and then reenter all the diagrams by hand.   ****   Then, on July 1 another miracle happens! You are done with the design!   Rather than go to your boss and complain, you stock your middle desk drawer with some vodka.   **** They threw a party to celebrate the on-time completion of the design phase and their graduation to CMM level 3. This time, you find BB's speech so stirring that you have to use the restroom before it begins. New banners and plaques are all over your workplace. They show pictures of eagles and mountain climbers, and they talk about teamwork and empowerment. They read better after a few scotches. That reminds you that you need to clear out your file cabinet to make room for the brandy. You and your team begin to code. But you rapidly discover that the design is lacking in some significant areas. Actually, it's lacking any significance at all. You convene a design session in one of the conference rooms to try to work through some of the nastier problems. But your boss catches you at it and disbands the meeting, saying, "The design phase is over. The only allowable activity is coding. Now get back to it."   ****   The code generated by Dandelion is really hideous. It turns out that you and your team were using association and aggregation the wrong way, after all. All the generated code has to be edited to correct these flaws. Editing this code is extremely difficult because it has been instrumented with ugly comment blocks that have special syntax that Dandelion needs in order to keep the diagrams in sync with the code. If you accidentally alter one of these comments, the diagrams will be regenerated incorrectly. It turns out that "Round the Horn Engineering" requires an awful lot of effort. The more you try to keep the code compatible with Dandelion, the more errors Dandelion generates. In the end, you give up and decide to keep the diagrams up to date manually. A second later, you decide that there's no point in keeping the diagrams up to date at all. Besides, who has time?   Your boss hires a consultant to build tools to count the number of lines of code that are being produced. He puts a big thermometer graph on the wall with the number 1,000,000 on the top. Every day, he extends the red line to show how many lines have been added. Three days after the thermometer appears on the wall, your boss stops you in the hall. "That graph isn't growing quickly enough. We need to have a million lines done by October 1." "We aren't even sh-sh-sure that the proshect will require a m-million linezh," you blather. "We have to have a million lines done by October 1," your boss reiterates. His points have grown again, and the Grecian formula he uses on them creates an aura of authority and competence. "Are you sure your comment blocks are big enough?" Then, in a flash of managerial insight, he says, "I have it! I want you to institute a new policy among the engineers. No line of code is to be longer than 20 characters. Any such line must be split into two or more preferably more. All existing code needs to be reworked to this standard. That'll get our line count up!"   You decide not to tell him that this will require two unscheduled work months. You decide not to tell him anything at all. You decide that intravenous injections of pure ethanol are the only solution. You make the appropriate arrangements. Hack, hack, hack, and hack. You and your team madly code away. By August 1, your boss, frowning at the thermometer on the wall, institutes a mandatory 50-hour workweek.   Hack, hack, hack, and hack. By September 1st, the thermometer is at 1.2 million lines and your boss asks you to write a report describing why you exceeded the coding budget by 20 percent. He institutes mandatory Saturdays and demands that the project be brought back down to a million lines. You start a campaign of remerging lines. Hack, hack, hack, and hack. Tempers are flaring; people are quitting; QA is raining trouble reports down on you. Customers are demanding installation and user manuals; salespeople are demanding advance demonstrations for special customers; the requirements document is still thrashing, the marketing folks are complaining that the product isn't anything like they specified, and the liquor store won't accept your credit card anymore. Something has to give.    On September 15, BB calls a meeting. As he enters the room, his points are emitting clouds of steam. When he speaks, the bass overtones of his carefully manicured voice cause the pit of your stomach to roll over. "The QA manager has told me that this project has less than 50 percent of the required features implemented. He has also informed me that the system crashes all the time, yields wrong results, and is hideously slow. He has also complained that he cannot keep up with the continuous train of daily releases, each more buggy than the last!" He stops for a few seconds, visibly trying to compose himself. "The QA manager estimates that, at this rate of development, we won't be able to ship the product until December!" Actually, you think it's more like March, but you don't say anything. "December!" BB roars with such derision that people duck their heads as though he were pointing an assault rifle at them. "December is absolutely out of the question. Team leaders, I want new estimates on my desk in the morning. I am hereby mandating 65-hour work weeks until this project is complete. And it better be complete by November 1."   As he leaves the conference room, he is heard to mutter: "Empowermentbah!" * * * Your boss is bald; his points are mounted on BB's wall. The fluorescent lights reflecting off his pate momentarily dazzle you. "Do you have anything to drink?" he asks. Having just finished your last bottle of Boone's Farm, you pull a bottle of Thunderbird from your bookshelf and pour it into his coffee mug. "What's it going to take to get this project done? " he asks. "We need to freeze the requirements, analyze them, design them, and then implement them," you say callously. "By November 1?" your boss exclaims incredulously. "No way! Just get back to coding the damned thing." He storms out, scratching his vacant head.   A few days later, you find that your boss has been transferred to the corporate research division. Turnover has skyrocketed. Customers, informed at the last minute that their orders cannot be fulfilled on time, have begun to cancel their orders. Marketing is re-evaluating whether this product aligns with the overall goals of the company. Memos fly, heads roll, policies change, and things are, overall, pretty grim. Finally, by March, after far too many sixty-five hour weeks, a very shaky version of the software is ready. In the field, bug-discovery rates are high, and the technical support staff are at their wits' end, trying to cope with the complaints and demands of the irate customers. Nobody is happy.   In April, BB decides to buy his way out of the problem by licensing a product produced by Rupert Industries and redistributing it. The customers are mollified, the marketing folks are smug, and you are laid off.     Rupert Industries: Project Alpha   Your name is Robert. The date is January 3, 2001. The quiet hours spent with your family this holiday have left you refreshed and ready for work. You are sitting in a conference room with your team of professionals. The manager of the division called the meeting. "We have some ideas for a new project," says the division manager. Call him Russ. He is a high-strung British chap with more energy than a fusion reactor. He is ambitious and driven but understands the value of a team. Russ describes the essence of the new market opportunity the company has identified and introduces you to Jane, the marketing manager, who is responsible for defining the products that will address it. Addressing you, Jane says, "We'd like to start defining our first product offering as soon as possible. When can you and your team meet with me?" You reply, "We'll be done with the current iteration of our project this Friday. We can spare a few hours for you between now and then. After that, we'll take a few people from the team and dedicate them to you. We'll begin hiring their replacements and the new people for your team immediately." "Great," says Russ, "but I want you to understand that it is critical that we have something to exhibit at the trade show coming up this July. If we can't be there with something significant, we'll lose the opportunity."   "I understand," you reply. "I don't yet know what it is that you have in mind, but I'm sure we can have something by July. I just can't tell you what that something will be right now. In any case, you and Jane are going to have complete control over what we developers do, so you can rest assured that by July, you'll have the most important things that can be accomplished in that time ready to exhibit."   Russ nods in satisfaction. He knows how this works. Your team has always kept him advised and allowed him to steer their development. He has the utmost confidence that your team will work on the most important things first and will produce a high-quality product.   * * *   "So, Robert," says Jane at their first meeting, "How does your team feel about being split up?" "We'll miss working with each other," you answer, "but some of us were getting pretty tired of that last project and are looking forward to a change. So, what are you people cooking up?" Jane beams. "You know how much trouble our customers currently have . . ." And she spends a half hour or so describing the problem and possible solution. "OK, wait a second" you respond. "I need to be clear about this." And so you and Jane talk about how this system might work. Some of her ideas aren't fully formed. You suggest possible solutions. She likes some of them. You continue discussing.   During the discussion, as each new topic is addressed, Jane writes user story cards. Each card represents something that the new system has to do. The cards accumulate on the table and are spread out in front of you. Both you and Jane point at them, pick them up, and make notes on them as you discuss the stories. The cards are powerful mnemonic devices that you can use to represent complex ideas that are barely formed.   At the end of the meeting, you say, "OK, I've got a general idea of what you want. I'm going to talk to the team about it. I imagine they'll want to run some experiments with various database structures and presentation formats. Next time we meet, it'll be as a group, and we'll start identifying the most important features of the system."   A week later, your nascent team meets with Jane. They spread the existing user story cards out on the table and begin to get into some of the details of the system. The meeting is very dynamic. Jane presents the stories in the order of their importance. There is much discussion about each one. The developers are concerned about keeping the stories small enough to estimate and test. So they continually ask Jane to split one story into several smaller stories. Jane is concerned that each story have a clear business value and priority, so as she splits them, she makes sure that this stays true.   The stories accumulate on the table. Jane writes them, but the developers make notes on them as needed. Nobody tries to capture everything that is said; the cards are not meant to capture everything but are simply reminders of the conversation.   As the developers become more comfortable with the stories, they begin writing estimates on them. These estimates are crude and budgetary, but they give Jane an idea of what the story will cost.   At the end of the meeting, it is clear that many more stories could be discussed. It is also clear that the most important stories have been addressed and that they represent several months worth of work. Jane closes the meeting by taking the cards with her and promising to have a proposal for the first release in the morning.   * * *   The next morning, you reconvene the meeting. Jane chooses five cards and places them on the table. "According to your estimates, these cards represent about one perfect team-week's worth of work. The last iteration of the previous project managed to get one perfect team-week done in 3 real weeks. If we can get these five stories done in 3 weeks, we'll be able to demonstrate them to Russ. That will make him feel very comfortable about our progress." Jane is pushing it. The sheepish look on her face lets you know that she knows it too. You reply, "Jane, this is a new team, working on a new project. It's a bit presumptuous to expect that our velocity will be the same as the previous team's. However, I met with the team yesterday afternoon, and we all agreed that our initial velocity should, in fact, be set to one perfectweek for every 3 real-weeks. So you've lucked out on this one." "Just remember," you continue, "that the story estimates and the story velocity are very tentative at this point. We'll learn more when we plan the iteration and even more when we implement it."   Jane looks over her glasses at you as if to say "Who's the boss around here, anyway?" and then smiles and says, "Yeah, don't worry. I know the drill by now."Jane then puts 15 more cards on the table. She says, "If we can get all these cards done by the end of March, we can turn the system over to our beta test customers. And we'll get good feedback from them."   You reply, "OK, so we've got our first iteration defined, and we have the stories for the next three iterations after that. These four iterations will make our first release."   "So," says Jane, can you really do these five stories in the next 3 weeks?" "I don't know for sure, Jane," you reply. "Let's break them down into tasks and see what we get."   So Jane, you, and your team spend the next several hours taking each of the five stories that Jane chose for the first iteration and breaking them down into small tasks. The developers quickly realize that some of the tasks can be shared between stories and that other tasks have commonalities that can probably be taken advantage of. It is clear that potential designs are popping into the developers' heads. From time to time, they form little discussion knots and scribble UML diagrams on some cards.   Soon, the whiteboard is filled with the tasks that, once completed, will implement the five stories for this iteration. You start the sign-up process by saying, "OK, let's sign up for these tasks." "I'll take the initial database generation." Says Pete. "That's what I did on the last project, and this doesn't look very different. I estimate it at two of my perfect workdays." "OK, well, then, I'll take the login screen," says Joe. "Aw, darn," says Elaine, the junior member of the team, "I've never done a GUI, and kinda wanted to try that one."   "Ah, the impatience of youth," Joe says sagely, with a wink in your direction. "You can assist me with it, young Jedi." To Jane: "I think it'll take me about three of my perfect workdays."   One by one, the developers sign up for tasks and estimate them in terms of their own perfect workdays. Both you and Jane know that it is best to let the developers volunteer for tasks than to assign the tasks to them. You also know full well that you daren't challenge any of the developers' estimates. You know these people, and you trust them. You know that they are going to do the very best they can.   The developers know that they can't sign up for more perfect workdays than they finished in the last iteration they worked on. Once each developer has filled his or her schedule for the iteration, they stop signing up for tasks.   Eventually, all the developers have stopped signing up for tasks. But, of course, tasks are still left on the board.   "I was worried that that might happen," you say, "OK, there's only one thing to do, Jane. We've got too much to do in this iteration. What stories or tasks can we remove?" Jane sighs. She knows that this is the only option. Working overtime at the beginning of a project is insane, and projects where she's tried it have not fared well.   So Jane starts to remove the least-important functionality. "Well, we really don't need the login screen just yet. We can simply start the system in the logged-in state." "Rats!" cries Elaine. "I really wanted to do that." "Patience, grasshopper." says Joe. "Those who wait for the bees to leave the hive will not have lips too swollen to relish the honey." Elaine looks confused. Everyone looks confused. "So . . .," Jane continues, "I think we can also do away with . . ." And so, bit by bit, the list of tasks shrinks. Developers who lose a task sign up for one of the remaining ones.   The negotiation is not painless. Several times, Jane exhibits obvious frustration and impatience. Once, when tensions are especially high, Elaine volunteers, "I'll work extra hard to make up some of the missing time." You are about to correct her when, fortunately, Joe looks her in the eye and says, "When once you proceed down the dark path, forever will it dominate your destiny."   In the end, an iteration acceptable to Jane is reached. It's not what Jane wanted. Indeed, it is significantly less. But it's something the team feels that can be achieved in the next 3 weeks.   And, after all, it still addresses the most important things that Jane wanted in the iteration. "So, Jane," you say when things had quieted down a bit, "when can we expect acceptance tests from you?" Jane sighs. This is the other side of the coin. For every story the development team implements,   Jane must supply a suite of acceptance tests that prove that it works. And the team needs these long before the end of the iteration, since they will certainly point out differences in the way Jane and the developers imagine the system's behaviour.   "I'll get you some example test scripts today," Jane promises. "I'll add to them every day after that. You'll have the entire suite by the middle of the iteration."   * * *   The iteration begins on Monday morning with a flurry of Class, Responsibilities, Collaborators sessions. By midmorning, all the developers have assembled into pairs and are rapidly coding away. "And now, my young apprentice," Joe says to Elaine, "you shall learn the mysteries of test-first design!"   "Wow, that sounds pretty rad," Elaine replies. "How do you do it?" Joe beams. It's clear that he has been anticipating this moment. "OK, what does the code do right now?" "Huh?" replied Elaine, "It doesn't do anything at all; there is no code."   "So, consider our task; can you think of something the code should do?" "Sure," Elaine said with youthful assurance, "First, it should connect to the database." "And thereupon, what must needs be required to connecteth the database?" "You sure talk weird," laughed Elaine. "I think we'd have to get the database object from some registry and call the Connect() method. "Ah, astute young wizard. Thou perceives correctly that we requireth an object within which we can cacheth the database object." "Is 'cacheth' really a word?" "It is when I say it! So, what test can we write that we know the database registry should pass?" Elaine sighs. She knows she'll just have to play along. "We should be able to create a database object and pass it to the registry in a Store() method. And then we should be able to pull it out of the registry with a Get() method and make sure it's the same object." "Oh, well said, my prepubescent sprite!" "Hay!" "So, now, let's write a test function that proves your case." "But shouldn't we write the database object and registry object first?" "Ah, you've much to learn, my young impatient one. Just write the test first." "But it won't even compile!" "Are you sure? What if it did?" "Uh . . ." "Just write the test, Elaine. Trust me." And so Joe, Elaine, and all the other developers began to code their tasks, one test case at a time. The room in which they worked was abuzz with the conversations between the pairs. The murmur was punctuated by an occasional high five when a pair managed to finish a task or a difficult test case.   As development proceeded, the developers changed partners once or twice a day. Each developer got to see what all the others were doing, and so knowledge of the code spread generally throughout the team.   Whenever a pair finished something significant whether a whole task or simply an important part of a task they integrated what they had with the rest of the system. Thus, the code base grew daily, and integration difficulties were minimized.   The developers communicated with Jane on a daily basis. They'd go to her whenever they had a question about the functionality of the system or the interpretation of an acceptance test case.   Jane, good as her word, supplied the team with a steady stream of acceptance test scripts. The team read these carefully and thereby gained a much better understanding of what Jane expected the system to do. By the beginning of the second week, there was enough functionality to demonstrate to Jane. She watched eagerly as the demonstration passed test case after test case. "This is really cool," Jane said as the demonstration finally ended. "But this doesn't seem like one-third of the tasks. Is your velocity slower than anticipated?"   You grimace. You'd been waiting for a good time to mention this to Jane but now she was forcing the issue. "Yes, unfortunately, we are going more slowly than we had expected. The new application server we are using is turning out to be a pain to configure. Also, it takes forever to reboot, and we have to reboot it whenever we make even the slightest change to its configuration."   Jane eyes you with suspicion. The stress of last Monday's negotiations had still not entirely dissipated. She says, "And what does this mean to our schedule? We can't slip it again, we just can't. Russ will have a fit! He'll haul us all into the woodshed and ream us some new ones."   You look Jane right in the eyes. There's no pleasant way to give someone news like this. So you just blurt out, "Look, if things keep going like they're going, we're not going to be done with everything by next Friday. Now it's possible that we'll figure out a way to go faster. But, frankly, I wouldn't depend on that. You should start thinking about one or two tasks that could be removed from the iteration without ruining the demonstration for Russ. Come hell or high water, we are going to give that demonstration on Friday, and I don't think you want us to choose which tasks to omit."   "Aw forchrisakes!" Jane barely manages to stifle yelling that last word as she stalks away, shaking her head. Not for the first time, you say to yourself, "Nobody ever promised me project management would be easy." You are pretty sure it won't be the last time, either.   Actually, things went a bit better than you had hoped. The team did, in fact, have to drop one task from the iteration, but Jane had chosen wisely, and the demonstration for Russ went without a hitch. Russ was not impressed with the progress, but neither was he dismayed. He simply said, "This is pretty good. But remember, we have to be able to demonstrate this system at the trade show in July, and at this rate, it doesn't look like you'll have all that much to show." Jane, whose attitude had improved dramatically with the completion of the iteration, responded to Russ by saying, "Russ, this team is working hard, and well. When July comes around, I am confident that we'll have something significant to demonstrate. It won't be everything, and some of it may be smoke and mirrors, but we'll have something."   Painful though the last iteration was, it had calibrated your velocity numbers. The next iteration went much better. Not because your team got more done than in the last iteration but simply because the team didn't have to remove any tasks or stories in the middle of the iteration.   By the start of the fourth iteration, a natural rhythm has been established. Jane, you, and the team know exactly what to expect from one another. The team is running hard, but the pace is sustainable. You are confident that the team can keep up this pace for a year or more.   The number of surprises in the schedule diminishes to near zero; however, the number of surprises in the requirements does not. Jane and Russ frequently look over the growing system and make recommendations or changes to the existing functionality. But all parties realize that these changes take time and must be scheduled. So the changes do not cause anyone's expectations to be violated. In March, there is a major demonstration of the system to the board of directors. The system is very limited and is not yet in a form good enough to take to the trade show, but progress is steady, and the board is reasonably impressed.   The second release goes even more smoothly than the first. By now, the team has figured out a way to automate Jane's acceptance test scripts. The team has also refactored the design of the system to the point that it is really easy to add new features and change old ones. The second release was done by the end of June and was taken to the trade show. It had less in it than Jane and Russ would have liked, but it did demonstrate the most important features of the system. Although customers at the trade show noticed that certain features were missing, they were very impressed overall. You, Russ, and Jane all returned from the trade show with smiles on your faces. You all felt as though this project was a winner.   Indeed, many months later, you are contacted by Rufus Inc. That company had been working on a system like this for its internal operations. Rufus has canceled the development of that system after a death-march project and is negotiating to license your technology for its environment.   Indeed, things are looking up!

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  • Q1 2010 New Feature: Paging with RadGridView for Silverlight and WPF

    We are glad to announce that the Q1 2010 Release has added another weapon to RadGridViews growing arsenal of features. This is the brand new RadDataPager control which provides the user interface for paging through a collection of data. The good news is that RadDataPager can be used to page any collection. It does not depend on RadGridView in any way, so you will be free to use it with the rest of your ItemsControls if you chose to do so. Before you read on, you might want to download the samples solution that I have attached. It contains a sample project for every scenario that I will discuss later on. Looking at the code while reading will make things much easier for you. There is something for everyone among the 10 Visual Studio projects that are included in the solution. So go and grab it. I. Paging essentials The single most important piece of software concerning paging in Silverlight is the System.ComponentModel.IPagedCollectionView interface. Those of you who are on the WPF front need not worry though. As you might already know, Teleriks Silverlight and WPF controls is share the same code-base. Since WPF does not contain a similar interface, Telerik has provided its own Telerik.Windows.Data.IPagedCollectionView. The IPagedCollectionView interface contains several important members which are used by RadGridView to perform the actual paging. Silverlight provides a default implementation of this interface which, naturally, is called PagedCollectionView. You should definitely take a look at its source code in case you are interested in what is going on under the hood. But this is not a prerequisite for our discussion. The WPF default implementation of the interface is Teleriks QueryableCollectionView which, among many other interfaces, implements IPagedCollectionView. II. No Paging In order to gradually build up my case, I will start with a very simple example that lacks paging whatsoever. It might sound stupid, but this will help us build on top of this paging-devoid example. Let us imagine that we have the simplest possible scenario. That is a simple IEnumerable and an ItemsControl that shows its contents. This will look like this: No Paging IEnumerable itemsSource = Enumerable.Range(0, 1000); this.itemsControl.ItemsSource = itemsSource; XAML <Border Grid.Row="0" BorderBrush="Black" BorderThickness="1" Margin="5">     <ListBox Name="itemsControl"/> </Border> <Border Grid.Row="1" BorderBrush="Black" BorderThickness="1" Margin="5">     <TextBlock Text="No Paging"/> </Border> Nothing special for now. Just some data displayed in a ListBox. The two sample projects in the solution that I have attached are: NoPaging_WPF NoPaging_SL3 With every next sample those two project will evolve in some way or another. III. Paging simple collections The single most important property of RadDataPager is its Source property. This is where you pass in your collection of data for paging. More often than not your collection will not be an IPagedCollectionView. It will either be a simple List<T>, or an ObservableCollection<T>, or anything that is simply IEnumerable. Unless you had paging in mind when you designed your project, it is almost certain that your data source will not be pageable out of the box. So what are the options? III. 1. Wrapping the simple collection in an IPagedCollectionView If you look at the constructors of PagedCollectionView and QueryableCollectionView you will notice that you can pass in a simple IEnumerable as a parameter. Those two classes will wrap it and provide paging capabilities over your original data. In fact, this is what RadGridView does internally. It wraps your original collection in an QueryableCollectionView in order to easily perform many useful tasks such as filtering, sorting, and others, but in our case the most important one is paging. So let us start our series of examples with the most simplistic one. Imagine that you have a simple IEnumerable which is the source for an ItemsControl. Here is how to wrap it in order to enable paging: Silverlight IEnumerable itemsSource = Enumerable.Range(0, 1000); var pagedSource = new PagedCollectionView(itemsSource); this.radDataPager.Source = pagedSource; this.itemsControl.ItemsSource = pagedSource; WPF IEnumerable itemsSource = Enumerable.Range(0, 1000); var pagedSource = new QueryableCollectionView(itemsSource); this.radDataPager.Source = pagedSource; this.itemsControl.ItemsSource = pagedSource; XAML <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <ListBox Name="itemsControl"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> This will do the trick. It is quite simple, isnt it? The two sample projects in the solution that I have attached are: PagingSimpleCollectionWithWrapping_WPF PagingSimpleCollectionWithWrapping_SL3 III. 2. Binding to RadDataPager.PagedSource In case you do not like this approach there is a better one. When you assign an IEnumerable as the Source of a RadDataPager it will automatically wrap it in a QueryableCollectionView and expose it through its PagedSource property. From then on, you can attach any number of ItemsControls to the PagedSource and they will be automatically paged. Here is how to do this entirely in XAML: Using RadDataPager.PagedSource <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1" Margin="5">     <ListBox Name="itemsControl"              ItemsSource="{Binding PagedSource, ElementName=radDataPager}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding ItemsSource}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> The two sample projects in the solution that I have attached are: PagingSimpleCollectionWithPagedSource_WPF PagingSimpleCollectionWithPagedSource_SL3 IV. Paging collections implementing IPagedCollectionView Those of you who are using WCF RIA Services should feel very lucky. After a quick look with Reflector or the debugger we can see that the DomainDataSource.Data property is in fact an instance of the DomainDataSourceView class. This class implements a handful of useful interfaces: ICollectionView IEnumerable INotifyCollectionChanged IEditableCollectionView IPagedCollectionView INotifyPropertyChanged Luckily, IPagedCollectionView is among them which lets you do the whole paging in the server. So lets do this. We will add a DomainDataSource control to our page/window and connect the items control and the pager to it. Here is how to do this: MainPage <riaControls:DomainDataSource x:Name="invoicesDataSource"                               AutoLoad="True"                               QueryName="GetInvoicesQuery">     <riaControls:DomainDataSource.DomainContext>         <services:ChinookDomainContext/>     </riaControls:DomainDataSource.DomainContext> </riaControls:DomainDataSource> <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <ListBox Name="itemsControl"              ItemsSource="{Binding Data, ElementName=invoicesDataSource}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding Data, ElementName=invoicesDataSource}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> By the way, you can replace the ListBox from the above code snippet with any other ItemsControl. It can be RadGridView, it can be the MS DataGrid, you name it. Essentially, RadDataPager is sending paging commands to the the DomainDataSource.Data. It does not care who, what, or how many different controls are bound to this same Data property of the DomainDataSource control. So if you would like to experiment with this, you can throw in any number of other ItemsControls next to the ListBox, bind them in the same manner, and all of them will be paged by our single RadDataPager. Furthermore, you can throw in any number of RadDataPagers and bind them to the same property. Then when you page with any one of them will automatically update all of the rest. The whole picture is simply beautiful and we can do all of this thanks to WCF RIA Services. The two sample projects (Silverlight only) in the solution that I have attached are: PagingIPagedCollectionView PagingIPagedCollectionView.Web IV. Paging RadGridView While you can replace the ListBox in any of the above examples with a RadGridView, RadGridView offers something extra. Similar to the DomainDataSource.Data property, the RadGridView.Items collection implements the IPagedCollectionView interface. So you are already thinking: Then why not bind the Source property of RadDataPager to RadGridView.Items? Well thats exactly what you can do and you will start paging RadGridView out-of-the-box. It is as simple as that, no code-behind is involved: MainPage <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1" Margin="5">     <telerikGrid:RadGridView Name="radGridView"                              ItemsSource="{Binding ItemsSource}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding Items, ElementName=radGridView}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> The two sample projects in the solution that I have attached are: PagingRadGridView_SL3 PagingRadGridView_WPF With this last example I think I have covered every possible paging combination. In case you would like to see an example of something that I have not covered, please let me know. Also, make sure you check out those great online examples: WCF RIA Services with DomainDataSource Paging Configurator Endless Paging Paging Any Collection Paging RadGridView Happy Paging! Download Full Source Code Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Writing Unit Tests for ASP.NET Web API Controller

    - by shiju
    In this blog post, I will write unit tests for a ASP.NET Web API controller in the EFMVC reference application. Let me introduce the EFMVC app, If you haven't heard about EFMVC. EFMVC is a simple app, developed as a reference implementation for demonstrating ASP.NET MVC, EF Code First, ASP.NET Web API, Domain-Driven Design (DDD), Test-Driven Development (DDD). The current version is built with ASP.NET MVC 4, EF Code First 5, ASP.NET Web API, Autofac, AutoMapper, Nunit and Moq. All unit tests were written with Nunit and Moq. You can download the latest version of the reference app from http://efmvc.codeplex.com/ Unit Test for HTTP Get Let’s write a unit test class for verifying the behaviour of a ASP.NET Web API controller named CategoryController. Let’s define mock implementation for Repository class, and a Command Bus that is used for executing write operations.  [TestFixture] public class CategoryApiControllerTest { private Mock<ICategoryRepository> categoryRepository; private Mock<ICommandBus> commandBus; [SetUp] public void SetUp() {     categoryRepository = new Mock<ICategoryRepository>();     commandBus = new Mock<ICommandBus>(); } The code block below provides the unit test for a HTTP Get operation. [Test] public void Get_All_Returns_AllCategory() {     // Arrange        IEnumerable<CategoryWithExpense> fakeCategories = GetCategories();     categoryRepository.Setup(x => x.GetCategoryWithExpenses()).Returns(fakeCategories);     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()                 {                     Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }                 }     };     // Act     var categories = controller.Get();     // Assert     Assert.IsNotNull(categories, "Result is null");     Assert.IsInstanceOf(typeof(IEnumerable<CategoryWithExpense>),categories, "Wrong Model");             Assert.AreEqual(3, categories.Count(), "Got wrong number of Categories"); }        The GetCategories method is provided below: private static IEnumerable<CategoryWithExpense> GetCategories() {     IEnumerable<CategoryWithExpense> fakeCategories = new List<CategoryWithExpense> {     new CategoryWithExpense {CategoryId=1, CategoryName = "Test1", Description="Test1Desc", TotalExpenses=1000},     new CategoryWithExpense {CategoryId=2, CategoryName = "Test2", Description="Test2Desc",TotalExpenses=2000},     new CategoryWithExpense { CategoryId=3, CategoryName = "Test3", Description="Test3Desc",TotalExpenses=3000}       }.AsEnumerable();     return fakeCategories; } In the unit test method Get_All_Returns_AllCategory, we specify setup on the mocked type ICategoryrepository, for a call to GetCategoryWithExpenses method returns dummy data. We create an instance of the ApiController, where we have specified the Request property of the ApiController since the Request property is used to create a new HttpResponseMessage that will provide the appropriate HTTP status code along with response content data. Unit Tests are using for specifying the behaviour of components so that we have specified that Get operation will use the model type IEnumerable<CategoryWithExpense> for sending the Content data. The implementation of HTTP Get in the CategoryController is provided below: public IQueryable<CategoryWithExpense> Get() {     var categories = categoryRepository.GetCategoryWithExpenses().AsQueryable();     return categories; } Unit Test for HTTP Post The following are the behaviours we are going to implement for the HTTP Post: A successful HTTP Post  operation should return HTTP status code Created An empty Category should return HTTP status code BadRequest A successful HTTP Post operation should provide correct Location header information in the response for the newly created resource. Writing unit test for HTTP Post is required more information than we write for HTTP Get. In the HTTP Post implementation, we will call to Url.Link for specifying the header Location of Response as shown in below code block. var response = Request.CreateResponse(HttpStatusCode.Created, category); string uri = Url.Link("DefaultApi", new { id = category.CategoryId }); response.Headers.Location = new Uri(uri); return response; While we are executing Url.Link from unit tests, we have to specify HttpRouteData information from the unit test method. Otherwise, Url.Link will get a null value. The code block below shows the unit tests for specifying the behaviours for the HTTP Post operation. [Test] public void Post_Category_Returns_CreatedStatusCode() {     // Arrange        commandBus.Setup(c => c.Submit(It.IsAny<CreateOrUpdateCategoryCommand>())).Returns(new CommandResult(true));     Mapper.CreateMap<CategoryFormModel, CreateOrUpdateCategoryCommand>();          var httpConfiguration = new HttpConfiguration();     WebApiConfig.Register(httpConfiguration);     var httpRouteData = new HttpRouteData(httpConfiguration.Routes["DefaultApi"],         new HttpRouteValueDictionary { { "controller", "category" } });     var controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage(HttpMethod.Post, "http://localhost/api/category/")         {             Properties =             {                 { HttpPropertyKeys.HttpConfigurationKey, httpConfiguration },                 { HttpPropertyKeys.HttpRouteDataKey, httpRouteData }             }         }     };     // Act     CategoryModel category = new CategoryModel();     category.CategoryId = 1;     category.CategoryName = "Mock Category";     var response = controller.Post(category);               // Assert     Assert.AreEqual(HttpStatusCode.Created, response.StatusCode);     var newCategory = JsonConvert.DeserializeObject<CategoryModel>(response.Content.ReadAsStringAsync().Result);     Assert.AreEqual(string.Format("http://localhost/api/category/{0}", newCategory.CategoryId), response.Headers.Location.ToString()); } [Test] public void Post_EmptyCategory_Returns_BadRequestStatusCode() {     // Arrange        commandBus.Setup(c => c.Submit(It.IsAny<CreateOrUpdateCategoryCommand>())).Returns(new CommandResult(true));     Mapper.CreateMap<CategoryFormModel, CreateOrUpdateCategoryCommand>();     var httpConfiguration = new HttpConfiguration();     WebApiConfig.Register(httpConfiguration);     var httpRouteData = new HttpRouteData(httpConfiguration.Routes["DefaultApi"],         new HttpRouteValueDictionary { { "controller", "category" } });     var controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage(HttpMethod.Post, "http://localhost/api/category/")         {             Properties =             {                 { HttpPropertyKeys.HttpConfigurationKey, httpConfiguration },                 { HttpPropertyKeys.HttpRouteDataKey, httpRouteData }             }         }     };     // Act     CategoryModel category = new CategoryModel();     category.CategoryId = 0;     category.CategoryName = "";     // The ASP.NET pipeline doesn't run, so validation don't run.     controller.ModelState.AddModelError("", "mock error message");     var response = controller.Post(category);     // Assert     Assert.AreEqual(HttpStatusCode.BadRequest, response.StatusCode);   } In the above code block, we have written two unit methods, Post_Category_Returns_CreatedStatusCode and Post_EmptyCategory_Returns_BadRequestStatusCode. The unit test method Post_Category_Returns_CreatedStatusCode  verifies the behaviour 1 and 3, that we have defined in the beginning of the section “Unit Test for HTTP Post”. The unit test method Post_EmptyCategory_Returns_BadRequestStatusCode verifies the behaviour 2. For extracting the data from response, we call Content.ReadAsStringAsync().Result of HttpResponseMessage object and deserializeit it with Json Convertor. The implementation of HTTP Post in the CategoryController is provided below: // POST /api/category public HttpResponseMessage Post(CategoryModel category) {       if (ModelState.IsValid)     {         var command = new CreateOrUpdateCategoryCommand(category.CategoryId, category.CategoryName, category.Description);         var result = commandBus.Submit(command);         if (result.Success)         {                               var response = Request.CreateResponse(HttpStatusCode.Created, category);             string uri = Url.Link("DefaultApi", new { id = category.CategoryId });             response.Headers.Location = new Uri(uri);             return response;         }     }     else     {         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);     }     throw new HttpResponseException(HttpStatusCode.BadRequest); } The unit test implementation for HTTP Put and HTTP Delete are very similar to the unit test we have written for  HTTP Get. The complete unit tests for the CategoryController is given below: [TestFixture] public class CategoryApiControllerTest { private Mock<ICategoryRepository> categoryRepository; private Mock<ICommandBus> commandBus; [SetUp] public void SetUp() {     categoryRepository = new Mock<ICategoryRepository>();     commandBus = new Mock<ICommandBus>(); } [Test] public void Get_All_Returns_AllCategory() {     // Arrange        IEnumerable<CategoryWithExpense> fakeCategories = GetCategories();     categoryRepository.Setup(x => x.GetCategoryWithExpenses()).Returns(fakeCategories);     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()                 {                     Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }                 }     };     // Act     var categories = controller.Get();     // Assert     Assert.IsNotNull(categories, "Result is null");     Assert.IsInstanceOf(typeof(IEnumerable<CategoryWithExpense>),categories, "Wrong Model");             Assert.AreEqual(3, categories.Count(), "Got wrong number of Categories"); }        [Test] public void Get_CorrectCategoryId_Returns_Category() {     // Arrange        IEnumerable<CategoryWithExpense> fakeCategories = GetCategories();     categoryRepository.Setup(x => x.GetCategoryWithExpenses()).Returns(fakeCategories);     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()         {             Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }         }     };     // Act     var response = controller.Get(1);     // Assert     Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);     var category = JsonConvert.DeserializeObject<CategoryWithExpense>(response.Content.ReadAsStringAsync().Result);     Assert.AreEqual(1, category.CategoryId, "Got wrong number of Categories"); } [Test] public void Get_InValidCategoryId_Returns_NotFound() {     // Arrange        IEnumerable<CategoryWithExpense> fakeCategories = GetCategories();     categoryRepository.Setup(x => x.GetCategoryWithExpenses()).Returns(fakeCategories);     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()         {             Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }         }     };     // Act     var response = controller.Get(5);     // Assert     Assert.AreEqual(HttpStatusCode.NotFound, response.StatusCode);            } [Test] public void Post_Category_Returns_CreatedStatusCode() {     // Arrange        commandBus.Setup(c => c.Submit(It.IsAny<CreateOrUpdateCategoryCommand>())).Returns(new CommandResult(true));     Mapper.CreateMap<CategoryFormModel, CreateOrUpdateCategoryCommand>();          var httpConfiguration = new HttpConfiguration();     WebApiConfig.Register(httpConfiguration);     var httpRouteData = new HttpRouteData(httpConfiguration.Routes["DefaultApi"],         new HttpRouteValueDictionary { { "controller", "category" } });     var controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage(HttpMethod.Post, "http://localhost/api/category/")         {             Properties =             {                 { HttpPropertyKeys.HttpConfigurationKey, httpConfiguration },                 { HttpPropertyKeys.HttpRouteDataKey, httpRouteData }             }         }     };     // Act     CategoryModel category = new CategoryModel();     category.CategoryId = 1;     category.CategoryName = "Mock Category";     var response = controller.Post(category);               // Assert     Assert.AreEqual(HttpStatusCode.Created, response.StatusCode);     var newCategory = JsonConvert.DeserializeObject<CategoryModel>(response.Content.ReadAsStringAsync().Result);     Assert.AreEqual(string.Format("http://localhost/api/category/{0}", newCategory.CategoryId), response.Headers.Location.ToString()); } [Test] public void Post_EmptyCategory_Returns_BadRequestStatusCode() {     // Arrange        commandBus.Setup(c => c.Submit(It.IsAny<CreateOrUpdateCategoryCommand>())).Returns(new CommandResult(true));     Mapper.CreateMap<CategoryFormModel, CreateOrUpdateCategoryCommand>();     var httpConfiguration = new HttpConfiguration();     WebApiConfig.Register(httpConfiguration);     var httpRouteData = new HttpRouteData(httpConfiguration.Routes["DefaultApi"],         new HttpRouteValueDictionary { { "controller", "category" } });     var controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage(HttpMethod.Post, "http://localhost/api/category/")         {             Properties =             {                 { HttpPropertyKeys.HttpConfigurationKey, httpConfiguration },                 { HttpPropertyKeys.HttpRouteDataKey, httpRouteData }             }         }     };     // Act     CategoryModel category = new CategoryModel();     category.CategoryId = 0;     category.CategoryName = "";     // The ASP.NET pipeline doesn't run, so validation don't run.     controller.ModelState.AddModelError("", "mock error message");     var response = controller.Post(category);     // Assert     Assert.AreEqual(HttpStatusCode.BadRequest, response.StatusCode);   } [Test] public void Put_Category_Returns_OKStatusCode() {     // Arrange        commandBus.Setup(c => c.Submit(It.IsAny<CreateOrUpdateCategoryCommand>())).Returns(new CommandResult(true));     Mapper.CreateMap<CategoryFormModel, CreateOrUpdateCategoryCommand>();     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()         {             Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }         }     };     // Act     CategoryModel category = new CategoryModel();     category.CategoryId = 1;     category.CategoryName = "Mock Category";     var response = controller.Put(category.CategoryId,category);     // Assert     Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);    } [Test] public void Delete_Category_Returns_NoContentStatusCode() {     // Arrange              commandBus.Setup(c => c.Submit(It.IsAny<DeleteCategoryCommand >())).Returns(new CommandResult(true));     CategoryController controller = new CategoryController(commandBus.Object, categoryRepository.Object)     {         Request = new HttpRequestMessage()         {             Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }         }     };     // Act               var response = controller.Delete(1);     // Assert     Assert.AreEqual(HttpStatusCode.NoContent, response.StatusCode);   } private static IEnumerable<CategoryWithExpense> GetCategories() {     IEnumerable<CategoryWithExpense> fakeCategories = new List<CategoryWithExpense> {     new CategoryWithExpense {CategoryId=1, CategoryName = "Test1", Description="Test1Desc", TotalExpenses=1000},     new CategoryWithExpense {CategoryId=2, CategoryName = "Test2", Description="Test2Desc",TotalExpenses=2000},     new CategoryWithExpense { CategoryId=3, CategoryName = "Test3", Description="Test3Desc",TotalExpenses=3000}       }.AsEnumerable();     return fakeCategories; } }  The complete implementation for the Api Controller, CategoryController is given below: public class CategoryController : ApiController {       private readonly ICommandBus commandBus;     private readonly ICategoryRepository categoryRepository;     public CategoryController(ICommandBus commandBus, ICategoryRepository categoryRepository)     {         this.commandBus = commandBus;         this.categoryRepository = categoryRepository;     } public IQueryable<CategoryWithExpense> Get() {     var categories = categoryRepository.GetCategoryWithExpenses().AsQueryable();     return categories; }   // GET /api/category/5 public HttpResponseMessage Get(int id) {     var category = categoryRepository.GetCategoryWithExpenses().Where(c => c.CategoryId == id).SingleOrDefault();     if (category == null)     {         return Request.CreateResponse(HttpStatusCode.NotFound);     }     return Request.CreateResponse(HttpStatusCode.OK, category); }   // POST /api/category public HttpResponseMessage Post(CategoryModel category) {       if (ModelState.IsValid)     {         var command = new CreateOrUpdateCategoryCommand(category.CategoryId, category.CategoryName, category.Description);         var result = commandBus.Submit(command);         if (result.Success)         {                               var response = Request.CreateResponse(HttpStatusCode.Created, category);             string uri = Url.Link("DefaultApi", new { id = category.CategoryId });             response.Headers.Location = new Uri(uri);             return response;         }     }     else     {         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);     }     throw new HttpResponseException(HttpStatusCode.BadRequest); }   // PUT /api/category/5 public HttpResponseMessage Put(int id, CategoryModel category) {     if (ModelState.IsValid)     {         var command = new CreateOrUpdateCategoryCommand(category.CategoryId, category.CategoryName, category.Description);         var result = commandBus.Submit(command);         return Request.CreateResponse(HttpStatusCode.OK, category);     }     else     {         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);     }     throw new HttpResponseException(HttpStatusCode.BadRequest); }       // DELETE /api/category/5     public HttpResponseMessage Delete(int id)     {         var command = new DeleteCategoryCommand { CategoryId = id };         var result = commandBus.Submit(command);         if (result.Success)         {             return new HttpResponseMessage(HttpStatusCode.NoContent);         }             throw new HttpResponseException(HttpStatusCode.BadRequest);     } } Source Code The EFMVC app can download from http://efmvc.codeplex.com/ . The unit test project can be found from the project EFMVC.Tests and Web API project can be found from EFMVC.Web.API.

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  • Adding Client Validation To DataAnnotations DataType Attribute

    - by srkirkland
    The System.ComponentModel.DataAnnotations namespace contains a validation attribute called DataTypeAttribute, which takes an enum specifying what data type the given property conforms to.  Here are a few quick examples: public class DataTypeEntity { [DataType(DataType.Date)] public DateTime DateTime { get; set; }   [DataType(DataType.EmailAddress)] public string EmailAddress { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This attribute comes in handy when using ASP.NET MVC, because the type you specify will determine what “template” MVC uses.  Thus, for the DateTime property if you create a partial in Views/[loc]/EditorTemplates/Date.ascx (or cshtml for razor), that view will be used to render the property when using any of the Html.EditorFor() methods. One thing that the DataType() validation attribute does not do is any actual validation.  To see this, let’s take a look at the EmailAddress property above.  It turns out that regardless of the value you provide, the entity will be considered valid: //valid new DataTypeEntity {EmailAddress = "Foo"}; .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Hmmm.  Since DataType() doesn’t validate, that leaves us with two options: (1) Create our own attributes for each datatype to validate, like [Date], or (2) add validation into the DataType attribute directly.  In this post, I will show you how to hookup client-side validation to the existing DataType() attribute for a desired type.  From there adding server-side validation would be a breeze and even writing a custom validation attribute would be simple (more on that in future posts). Validation All The Way Down Our goal will be to leave our DataTypeEntity class (from above) untouched, requiring no reference to System.Web.Mvc.  Then we will make an ASP.NET MVC project that allows us to create a new DataTypeEntity and hookup automatic client-side date validation using the suggested “out-of-the-box” jquery.validate bits that are included with ASP.NET MVC 3.  For simplicity I’m going to focus on the only DateTime field, but the concept is generally the same for any other DataType. Building a DataTypeAttribute Adapter To start we will need to build a new validation adapter that we can register using ASP.NET MVC’s DataAnnotationsModelValidatorProvider.RegisterAdapter() method.  This method takes two Type parameters; The first is the attribute we are looking to validate with and the second is an adapter that should subclass System.Web.Mvc.ModelValidator. Since we are extending DataAnnotations we can use the subclass of ModelValidator called DataAnnotationsModelValidator<>.  This takes a generic argument of type DataAnnotations.ValidationAttribute, which lucky for us means the DataTypeAttribute will fit in nicely. So starting from there and implementing the required constructor, we get: public class DataTypeAttributeAdapter : DataAnnotationsModelValidator<DataTypeAttribute> { public DataTypeAttributeAdapter(ModelMetadata metadata, ControllerContext context, DataTypeAttribute attribute) : base(metadata, context, attribute) { } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now you have a full-fledged validation adapter, although it doesn’t do anything yet.  There are two methods you can override to add functionality, IEnumerable<ModelValidationResult> Validate(object container) and IEnumerable<ModelClientValidationRule> GetClientValidationRules().  Adding logic to the server-side Validate() method is pretty straightforward, and for this post I’m going to focus on GetClientValidationRules(). Adding a Client Validation Rule Adding client validation is now incredibly easy because jquery.validate is very powerful and already comes with a ton of validators (including date and regular expressions for our email example).  Teamed with the new unobtrusive validation javascript support we can make short work of our ModelClientValidationDateRule: public class ModelClientValidationDateRule : ModelClientValidationRule { public ModelClientValidationDateRule(string errorMessage) { ErrorMessage = errorMessage; ValidationType = "date"; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If your validation has additional parameters you can the ValidationParameters IDictionary<string,object> to include them.  There is a little bit of conventions magic going on here, but the distilled version is that we are defining a “date” validation type, which will be included as html5 data-* attributes (specifically data-val-date).  Then jquery.validate.unobtrusive takes this attribute and basically passes it along to jquery.validate, which knows how to handle date validation. Finishing our DataTypeAttribute Adapter Now that we have a model client validation rule, we can return it in the GetClientValidationRules() method of our DataTypeAttributeAdapter created above.  Basically I want to say if DataType.Date was provided, then return the date rule with a given error message (using ValidationAttribute.FormatErrorMessage()).  The entire adapter is below: public class DataTypeAttributeAdapter : DataAnnotationsModelValidator<DataTypeAttribute> { public DataTypeAttributeAdapter(ModelMetadata metadata, ControllerContext context, DataTypeAttribute attribute) : base(metadata, context, attribute) { }   public override System.Collections.Generic.IEnumerable<ModelClientValidationRule> GetClientValidationRules() { if (Attribute.DataType == DataType.Date) { return new[] { new ModelClientValidationDateRule(Attribute.FormatErrorMessage(Metadata.GetDisplayName())) }; }   return base.GetClientValidationRules(); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Putting it all together Now that we have an adapter for the DataTypeAttribute, we just need to tell ASP.NET MVC to use it.  The easiest way to do this is to use the built in DataAnnotationsModelValidatorProvider by calling RegisterAdapter() in your global.asax startup method. DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(DataTypeAttribute), typeof(DataTypeAttributeAdapter)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Show and Tell Let’s see this in action using a clean ASP.NET MVC 3 project.  First make sure to reference the jquery, jquery.vaidate and jquery.validate.unobtrusive scripts that you will need for client validation. Next, let’s make a model class (note we are using the same built-in DataType() attribute that comes with System.ComponentModel.DataAnnotations). public class DataTypeEntity { [DataType(DataType.Date, ErrorMessage = "Please enter a valid date (ex: 2/14/2011)")] public DateTime DateTime { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Then we make a create page with a strongly-typed DataTypeEntity model, the form section is shown below (notice we are just using EditorForModel): @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>Fields</legend>   @Html.EditorForModel()   <p> <input type="submit" value="Create" /> </p> </fieldset> } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The final step is to register the adapter in our global.asax file: DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(DataTypeAttribute), typeof(DataTypeAttributeAdapter)); Now we are ready to run the page: Looking at the datetime field’s html, we see that our adapter added some data-* validation attributes: <input type="text" value="1/1/0001" name="DateTime" id="DateTime" data-val-required="The DateTime field is required." data-val-date="Please enter a valid date (ex: 2/14/2011)" data-val="true" class="text-box single-line valid"> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here data-val-required was added automatically because DateTime is non-nullable, and data-val-date was added by our validation adapter.  Now if we try to add an invalid date: Our custom error message is displayed via client-side validation as soon as we tab out of the box.  If we didn’t include a custom validation message, the default DataTypeAttribute “The field {0} is invalid” would have been shown (of course we can change the default as well).  Note we did not specify server-side validation, but in this case we don’t have to because an invalid date will cause a server-side error during model binding. Conclusion I really like how easy it is to register new data annotations model validators, whether they are your own or, as in this post, supplements to existing validation attributes.  I’m still debating about whether adding the validation directly in the DataType attribute is the correct place to put it versus creating a dedicated “Date” validation attribute, but it’s nice to know either option is available and, as we’ve seen, simple to implement. I’m also working through the nascent stages of an open source project that will create validation attribute extensions to the existing data annotations providers using similar techniques as seen above (examples: Email, Url, EqualTo, Min, Max, CreditCard, etc).  Keep an eye on this blog and subscribe to my twitter feed (@srkirkland) if you are interested for announcements.

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  • Pure Server-Side Filtering with RadGridView and WCF RIA Services

    Those of you who are familiar with WCF RIA Services know that the DomainDataSource control provides a FilterDescriptors collection that enables you to filter data returned by the query on the server. We have been using this DomainDataSource feature in our RIA Services with DomainDataSource online example for almost an year now. In the example, we are listening for RadGridViews Filtering event in order to intercept any filtering that is performed on the client and translate it to something that the DomainDataSource will understand, in this case a System.Windows.Data.FilterDescriptor being added or removed from its FilterDescriptors collection. Think of RadGridView.FilterDescriptors as client-side filtering and of DomainDataSource.FilterDescriptors as server-side filtering. We no longer need the client-side one. With the introduction of the Custom Filtering Controls feature many new possibilities have opened. With these custom controls we no longer need to do any filtering on the client. I have prepared a very small project that demonstrates how to filter solely on the server by using a custom filtering control. As I have already mentioned filtering on the server is done through the FilterDescriptors collection of the DomainDataSource control. This collection holds instances of type System.Windows.Data.FilterDescriptor. The FilterDescriptor has three important properties: PropertyPath: Specifies the name of the property that we want to filter on (the left operand). Operator: Specifies the type of comparison to use when filtering. An instance of FilterOperator Enumeration. Value: The value to compare with (the right operand). An instance of the Parameter Class. By adding filters, you can specify that only entities which meet the condition in the filter are loaded from the domain context. In case you are not familiar with these concepts you might find Brad Abrams blog interesting. Now, our requirements are to create some kind of UI that will manipulate the DomainDataSource.FilterDescriptors collection. When it comes to collections, my first choice of course would be RadGridView. If you are not familiar with the Custom Filtering Controls concept I would strongly recommend getting acquainted with my step-by-step tutorial Custom Filtering with RadGridView for Silverlight and checking the online example out. I have created a simple custom filtering control that contains a RadGridView and several buttons. This control is aware of the DomainDataSource instance, since it is operating on its FilterDescriptors collection. In fact, the RadGridView that is inside it is bound to this collection. In order to display filters that are relevant for the current column only, I have applied a filter to the grid. This filter is a Telerik.Windows.Data.FilterDescriptor and is used to filter the little grid inside the custom control. It should not be confused with the DomainDataSource.FilterDescriptors collection that RadGridView is actually bound to. These are the RIA filters. Additionally, I have added several other features. For example, if you have specified a DataFormatString on your original column, the Value column inside the custom control will pick it up and format the filter values accordingly. Also, I have transferred the data type of the column that you are filtering to the Value column of the custom control. This will help the little RadGridView determine what kind of editor to show up when you begin edit, for example a date picker for DateTime columns. Finally, I have added four buttons two of them can be used to add or remove filters and the other two will communicate the changes you have made to the server. Here is the full source code of the DomainDataSourceFilteringControl. The XAML: <UserControl x:Class="PureServerSideFiltering.DomainDataSourceFilteringControl"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:telerikGrid="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView"     xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls"     Width="300">     <Border x:Name="LayoutRoot"             BorderThickness="1"             BorderBrush="#FF8A929E"             Padding="5"             Background="#FFDFE2E5">           <Grid>             <Grid.RowDefinitions>                 <RowDefinition Height="Auto"/>                 <RowDefinition Height="150"/>                 <RowDefinition Height="Auto"/>             </Grid.RowDefinitions>               <StackPanel Grid.Row="0"                         Margin="2"                         Orientation="Horizontal"                         HorizontalAlignment="Center">                 <telerik:RadButton Name="addFilterButton"                                   Click="OnAddFilterButtonClick"                                   Content="Add Filter"                                   Margin="2"                                   Width="96"/>                 <telerik:RadButton Name="removeFilterButton"                                   Click="OnRemoveFilterButtonClick"                                   Content="Remove Filter"                                   Margin="2"                                   Width="96"/>             </StackPanel>               <telerikGrid:RadGridView Name="filtersGrid"                                     Grid.Row="1"                                     Margin="2"                                     ItemsSource="{Binding FilterDescriptors}"                                     AddingNewDataItem="OnFilterGridAddingNewDataItem"                                     ColumnWidth="*"                                     ShowGroupPanel="False"                                     AutoGenerateColumns="False"                                     CanUserResizeColumns="False"                                     CanUserReorderColumns="False"                                     CanUserFreezeColumns="False"                                     RowIndicatorVisibility="Collapsed"                                     IsFilteringAllowed="False"                                     CanUserSortColumns="False">                 <telerikGrid:RadGridView.Columns>                     <telerikGrid:GridViewComboBoxColumn DataMemberBinding="{Binding Operator}"                                                         UniqueName="Operator"/>                     <telerikGrid:GridViewDataColumn Header="Value"                                                     DataMemberBinding="{Binding Value.Value}"                                                     UniqueName="Value"/>                 </telerikGrid:RadGridView.Columns>             </telerikGrid:RadGridView>               <StackPanel Grid.Row="2"                         Margin="2"                         Orientation="Horizontal"                         HorizontalAlignment="Center">                 <telerik:RadButton Name="filterButton"                                   Click="OnApplyFiltersButtonClick"                                   Content="Apply Filters"                                   Margin="2"                                   Width="96"/>                 <telerik:RadButton Name="clearButton"                                   Click="OnClearFiltersButtonClick"                                   Content="Clear Filters"                                   Margin="2"                                   Width="96"/>             </StackPanel>           </Grid>       </Border> </UserControl>   And the code-behind: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using Telerik.Windows.Controls.GridView; using System.Windows.Data; using Telerik.Windows.Controls; using Telerik.Windows.Data;   namespace PureServerSideFiltering {     /// <summary>     /// A custom filtering control capable of filtering purely server-side.     /// </summary>     public partial class DomainDataSourceFilteringControl : UserControl, IFilteringControl     {         // The main player here.         DomainDataSource domainDataSource;           // This is the name of the property that this column displays.         private string dataMemberName;           // This is the type of the property that this column displays.         private Type dataMemberType;           /// <summary>         /// Identifies the <see cref="IsActive"/> dependency property.         /// </summary>         /// <remarks>         /// The state of the filtering funnel (i.e. full or empty) is bound to this property.         /// </remarks>         public static readonly DependencyProperty IsActiveProperty =             DependencyProperty.Register(                 "IsActive",                 typeof(bool),                 typeof(DomainDataSourceFilteringControl),                 new PropertyMetadata(false));           /// <summary>         /// Gets or sets a value indicating whether the filtering is active.         /// </summary>         /// <remarks>         /// Set this to true if you want to lit-up the filtering funnel.         /// </remarks>         public bool IsActive         {             get { return (bool)GetValue(IsActiveProperty); }             set { SetValue(IsActiveProperty, value); }         }           /// <summary>         /// Gets or sets the domain data source.         /// We need this in order to work on its FilterDescriptors collection.         /// </summary>         /// <value>The domain data source.</value>         public DomainDataSource DomainDataSource         {             get { return this.domainDataSource; }             set { this.domainDataSource = value; }         }           public System.Windows.Data.FilterDescriptorCollection FilterDescriptors         {             get { return this.DomainDataSource.FilterDescriptors; }         }           public DomainDataSourceFilteringControl()         {             InitializeComponent();         }           public void Prepare(GridViewBoundColumnBase column)         {             this.LayoutRoot.DataContext = this;               if (this.DomainDataSource == null)             {                 // Sorry, but we need a DomainDataSource. Can't do anything without it.                 return;             }               // This is the name of the property that this column displays.             this.dataMemberName = column.GetDataMemberName();               // This is the type of the property that this column displays.             // We need this in order to see which FilterOperators to feed to the combo-box column.             this.dataMemberType = column.DataType;               // We will use our magic Type extension method to see which operators are applicable for             // this data type. You can go to the extension method body and see what it does.             ((GridViewComboBoxColumn)this.filtersGrid.Columns["Operator"]).ItemsSource                 = this.dataMemberType.ApplicableFilterOperators();               // This is very nice as well. We will tell the Value column its data type. In this way             // RadGridView will pick up the best editor according to the data type. For example,             // if the data type of the value is DateTime, you will be editing it with a DatePicker.             // Nice!             ((GridViewDataColumn)this.filtersGrid.Columns["Value"]).DataType = this.dataMemberType;               // Yet another nice feature. We will transfer the original DataFormatString (if any) to             // the Value column. In this way if you have specified a DataFormatString for the original             // column, you will see all filter values formatted accordingly.             ((GridViewDataColumn)this.filtersGrid.Columns["Value"]).DataFormatString = column.DataFormatString;               // This is important. Since our little filtersGrid will be bound to the entire collection             // of this.domainDataSource.FilterDescriptors, we need to set a Telerik filter on the             // grid so that it will display FilterDescriptor which are relevane to this column ONLY!             Telerik.Windows.Data.FilterDescriptor columnFilter = new Telerik.Windows.Data.FilterDescriptor("PropertyPath"                 , Telerik.Windows.Data.FilterOperator.IsEqualTo                 , this.dataMemberName);             this.filtersGrid.FilterDescriptors.Add(columnFilter);               // We want to listen for this in order to activate and de-activate the UI funnel.             this.filtersGrid.Items.CollectionChanged += this.OnFilterGridItemsCollectionChanged;         }           /// <summary>         // Since the DomainDataSource is a little bit picky about adding uninitialized FilterDescriptors         // to its collection, we will prepare each new instance with some default values and then         // the user can change them later. Go to the event handler to see how we do this.         /// </summary>         void OnFilterGridAddingNewDataItem(object sender, GridViewAddingNewEventArgs e)         {             // We need to initialize the new instance with some values and let the user go on from here.             System.Windows.Data.FilterDescriptor newFilter = new System.Windows.Data.FilterDescriptor();               // This is a must. It should know what member it is filtering on.             newFilter.PropertyPath = this.dataMemberName;               // Initialize it with one of the allowed operators.             // TypeExtensions.ApplicableFilterOperators method for more info.             newFilter.Operator = this.dataMemberType.ApplicableFilterOperators().First();               if (this.dataMemberType == typeof(DateTime))             {                 newFilter.Value.Value = DateTime.Now;             }             else if (this.dataMemberType == typeof(string))             {                 newFilter.Value.Value = "<enter text>";             }             else if (this.dataMemberType.IsValueType)             {                 // We need something non-null for all value types.                 newFilter.Value.Value = Activator.CreateInstance(this.dataMemberType);             }               // Let the user edit the new filter any way he/she likes.             e.NewObject = newFilter;         }           void OnFilterGridItemsCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)         {             // We are active only if we have any filters define. In this case the filtering funnel will lit-up.             this.IsActive = this.filtersGrid.Items.Count > 0;         }           private void OnApplyFiltersButtonClick(object sender, RoutedEventArgs e)         {             if (this.DomainDataSource.IsLoadingData)             {                 return;             }               // Comment this if you want the popup to stay open after the button is clicked.             this.ClosePopup();               // Since this.domainDataSource.AutoLoad is false, this will take into             // account all filtering changes that the user has made since the last             // Load() and pull the new data to the client.             this.DomainDataSource.Load();         }           private void OnClearFiltersButtonClick(object sender, RoutedEventArgs e)         {             if (this.DomainDataSource.IsLoadingData)             {                 return;             }               // We want to remove ONLY those filters from the DomainDataSource             // that this control is responsible for.             this.DomainDataSource.FilterDescriptors                 .Where(fd => fd.PropertyPath == this.dataMemberName) // Only "our" filters.                 .ToList()                 .ForEach(fd => this.DomainDataSource.FilterDescriptors.Remove(fd)); // Bye-bye!               // Comment this if you want the popup to stay open after the button is clicked.             this.ClosePopup();               // After we did our housekeeping, get the new data to the client.             this.DomainDataSource.Load();         }           private void OnAddFilterButtonClick(object sender, RoutedEventArgs e)         {             if (this.DomainDataSource.IsLoadingData)             {                 return;             }               // Let the user enter his/or her requirements for a new filter.             this.filtersGrid.BeginInsert();             this.filtersGrid.UpdateLayout();         }           private void OnRemoveFilterButtonClick(object sender, RoutedEventArgs e)         {             if (this.DomainDataSource.IsLoadingData)             {                 return;             }               // Find the currently selected filter and destroy it.             System.Windows.Data.FilterDescriptor filterToRemove = this.filtersGrid.SelectedItem as System.Windows.Data.FilterDescriptor;             if (filterToRemove != null                 && this.DomainDataSource.FilterDescriptors.Contains(filterToRemove))             {                 this.DomainDataSource.FilterDescriptors.Remove(filterToRemove);             }         }           private void ClosePopup()         {             System.Windows.Controls.Primitives.Popup popup = this.ParentOfType<System.Windows.Controls.Primitives.Popup>();             if (popup != null)             {                 popup.IsOpen = false;             }         }     } }   Finally, we need to tell RadGridViews Columns to use this custom control instead of the default one. Here is how to do it: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Windows.Data; using Telerik.Windows.Data; using Telerik.Windows.Controls; using Telerik.Windows.Controls.GridView;   namespace PureServerSideFiltering {     public partial class MainPage : UserControl     {         public MainPage()         {             InitializeComponent();             this.grid.AutoGeneratingColumn += this.OnGridAutoGeneratingColumn;               // Uncomment this if you want the DomainDataSource to start pre-filtered.             // You will notice how our custom filtering controls will correctly read this information,             // populate their UI with the respective filters and lit-up the funnel to indicate that             // filtering is active. Go ahead and try it.             this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("Title", System.Windows.Data.FilterOperator.Contains, "Assistant"));             this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("HireDate", System.Windows.Data.FilterOperator.IsGreaterThan, new DateTime(1998, 12, 31)));             this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("HireDate", System.Windows.Data.FilterOperator.IsLessThanOrEqualTo, new DateTime(1999, 12, 31)));               this.employeesDataSource.Load();         }           /// <summary>         /// First of all, we will need to replace the default filtering control         /// of each column with out custom filtering control DomainDataSourceFilteringControl         /// </summary>         private void OnGridAutoGeneratingColumn(object sender, GridViewAutoGeneratingColumnEventArgs e)         {             GridViewBoundColumnBase dataColumn = e.Column as GridViewBoundColumnBase;             if (dataColumn != null)             {                 // We do not like ugly dates.                 if (dataColumn.DataType == typeof(DateTime))                 {                     dataColumn.DataFormatString = "{0:d}"; // Short date pattern.                       // Notice how this format will be later transferred to the Value column                     // of the grid that we have inside the DomainDataSourceFilteringControl.                 }                   // Replace the default filtering control with our.                 dataColumn.FilteringControl = new DomainDataSourceFilteringControl()                 {                     // Let the control know about the DDS, after all it will work directly on it.                     DomainDataSource = this.employeesDataSource                 };                   // Finally, lit-up the filtering funnel through the IsActive dependency property                 // in case there are some filters on the DDS that match our column member.                 string dataMemberName = dataColumn.GetDataMemberName();                 dataColumn.FilteringControl.IsActive =                     this.employeesDataSource.FilterDescriptors                     .Where(fd => fd.PropertyPath == dataMemberName)                     .Count() > 0;             }         }     } } The best part is that we are not only writing filters for the DomainDataSource we can read and load them. If the DomainDataSource has some pre-existing filters (like I have created in the code above), our control will read them and will populate its UI accordingly. Even the filtering funnel will light-up! Remember, the funnel is controlled by the IsActive property of our control. While this is just a basic implementation, the source code is absolutely yours and you can take it from here and extend it to match your specific business requirements. Below the main grid there is another debug grid. With its help you can monitor what filter descriptors are added and removed to the domain data source. Download Source Code. (You will have to have the AdventureWorks sample database installed on the default SQLExpress instance in order to run it.) Enjoy!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Changing CSS on the fly in a UIWebView on iPhone

    - by Shaggy Frog
    Let's say I'm developing an iPhone app that is a catalogue of cars. The user will choose a car from a list, and I will present a detail view for the car, which will describe things like top speed. The detail view will essentially be a UIWebView that is loading an existing HTML file. Different users will live in different parts of the world, so they will like to see the top speed for the car in whatever units are appropriate for their locale. Let's say there are two such units: SI (km/h) and conventional (mph). Let's also say the user will be able to change the display units by hitting a button on the screen; when that happens, the detail screen should switch to show the relevant units. So far, here's what I've done to try and solve this. The HTML might look something like this: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US"> <head> <title>Some Car</title> <link rel="stylesheet" media="screen" type="text/css" href="persistent.css" /> <link rel="alternate stylesheet" media="screen" type="text/css" href="si.css" title="si" /> <link rel="alternate stylesheet" media="screen" type="text/css" href="conventional.css" title="conventional" /> <script type="text/javascript" src="switch.js"></script> </head> <body> <h1>Some Car</h1> <div id="si"> <h2>Top Speed: 160 km/h</h2> </div> <div id="conventional"> <h2>Top Speed: 100 mph</h2> </div> </body> The peristent stylesheet, persistent.css: #si { display:none; } #conventional { display:none; } The first alternate stylesheet, si.css: #si { display:inline; } #conventional { display:none; } And the second alternate stylesheet, conventional.css: #si { display:none; } #conventional { display:inline; } Based on a tutorial at A List Apart, my switch.js looks something like this: function disableStyleSheet(title) { var i, a; for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) { if ((a.getAttribute("rel").indexOf("alt") != -1) && (a.getAttribute("title") == title)) { a.disabled = true; } } } function enableStyleSheet(title) { var i, a; for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) { if ((a.getAttribute("rel").indexOf("alt") != -1) && (a.getAttribute("title") == title)) { a.disabled = false; } } } function switchToSiStyleSheet() { disableStyleSheet("conventional"); enableStyleSheet("si"); } function switchToConventionalStyleSheet() { disableStyleSheet("si"); enableStyleSheet("conventional"); } My button action handler looks something like this: - (void)notesButtonAction:(id)sender { static BOOL isUsingSi = YES; if (isUsingSi) { NSString* command = [[NSString alloc] initWithString:@"switchToSiStyleSheet();"]; [self.webView stringByEvaluatingJavaScriptFromString:command]; [command release]; } else { NSString* command = [[NSString alloc] initWithFormat:@"switchToConventionalStyleSheet();"]; [self.webView stringByEvaluatingJavaScriptFromString:command]; [command release]; } isUsingSi = !isUsingSi; } Here's the first problem. The first time the button is hit, the UIWebView doesn't change. The second time it's hit, it looks like the conventional style sheet is loaded. The third time, it switches to the SI style sheet; the fourth time, back to the conventional, and so on. So, basically, only that first button press doesn't seem to do anything. Here's the second problem. I'm not sure how to switch to the correct style sheet upon initial load of the UIWebView. I tried this: - (void)webViewDidFinishLoad:(UIWebView *)webView { NSString* command = [[NSString alloc] initWithString:@"switchToSiStyleSheet();"]; [self.webView stringByEvaluatingJavaScriptFromString:command]; [command release]; } But, like the first button hit, it doesn't seem to do anything. Can anyone help me with these two problems?

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  • Silverlight Tree View with Multiple Levels

    - by psheriff
    There are many examples of the Silverlight Tree View that you will find on the web, however, most of them only show you how to go to two levels. What if you have more than two levels? This is where understanding exactly how the Hierarchical Data Templates works is vital. In this blog post, I am going to break down how these templates work so you can really understand what is going on underneath the hood. To start, let’s look at the typical two-level Silverlight Tree View that has been hard coded with the values shown below: <sdk:TreeView>  <sdk:TreeViewItem Header="Managers">    <TextBlock Text="Michael" />    <TextBlock Text="Paul" />  </sdk:TreeViewItem>  <sdk:TreeViewItem Header="Supervisors">    <TextBlock Text="John" />    <TextBlock Text="Tim" />    <TextBlock Text="David" />  </sdk:TreeViewItem></sdk:TreeView> Figure 1 shows you how this tree view looks when you run the Silverlight application. Figure 1: A hard-coded, two level Tree View. Next, let’s create three classes to mimic the hard-coded Tree View shown above. First, you need an Employee class and an EmployeeType class. The Employee class simply has one property called Name. The constructor is created to accept a “name” argument that you can use to set the Name property when you create an Employee object. public class Employee{  public Employee(string name)  {    Name = name;  }   public string Name { get; set; }} Finally you create an EmployeeType class. This class has one property called EmpType and contains a generic List<> collection of Employee objects. The property that holds the collection is called Employees. public class EmployeeType{  public EmployeeType(string empType)  {    EmpType = empType;    Employees = new List<Employee>();  }   public string EmpType { get; set; }  public List<Employee> Employees { get; set; }} Finally we have a collection class called EmployeeTypes created using the generic List<> class. It is in the constructor for this class where you will build the collection of EmployeeTypes and fill it with Employee objects: public class EmployeeTypes : List<EmployeeType>{  public EmployeeTypes()  {    EmployeeType type;            type = new EmployeeType("Manager");    type.Employees.Add(new Employee("Michael"));    type.Employees.Add(new Employee("Paul"));    this.Add(type);     type = new EmployeeType("Project Managers");    type.Employees.Add(new Employee("Tim"));    type.Employees.Add(new Employee("John"));    type.Employees.Add(new Employee("David"));    this.Add(type);  }} You now have a data hierarchy in memory (Figure 2) which is what the Tree View control expects to receive as its data source. Figure 2: A hierachial data structure of Employee Types containing a collection of Employee objects. To connect up this hierarchy of data to your Tree View you create an instance of the EmployeeTypes class in XAML as shown in line 13 of Figure 3. The key assigned to this object is “empTypes”. This key is used as the source of data to the entire Tree View by setting the ItemsSource property as shown in Figure 3, Callout #1. Figure 3: You need to start from the bottom up when laying out your templates for a Tree View. The ItemsSource property of the Tree View control is used as the data source in the Hierarchical Data Template with the key of employeeTypeTemplate. In this case there is only one Hierarchical Data Template, so any data you wish to display within that template comes from the collection of Employee Types. The TextBlock control in line 20 uses the EmpType property of the EmployeeType class. You specify the name of the Hierarchical Data Template to use in the ItemTemplate property of the Tree View (Callout #2). For the second (and last) level of the Tree View control you use a normal <DataTemplate> with the name of employeeTemplate (line 14). The Hierarchical Data Template in lines 17-21 sets its ItemTemplate property to the key name of employeeTemplate (Line 19 connects to Line 14). The source of the data for the <DataTemplate> needs to be a property of the EmployeeTypes collection used in the Hierarchical Data Template. In this case that is the Employees property. In the Employees property there is a “Name” property of the Employee class that is used to display the employee name in the second level of the Tree View (Line 15). What is important here is that your lowest level in your Tree View is expressed in a <DataTemplate> and should be listed first in your Resources section. The next level up in your Tree View should be a <HierarchicalDataTemplate> which has its ItemTemplate property set to the key name of the <DataTemplate> and the ItemsSource property set to the data you wish to display in the <DataTemplate>. The Tree View control should have its ItemsSource property set to the data you wish to display in the <HierarchicalDataTemplate> and its ItemTemplate property set to the key name of the <HierarchicalDataTemplate> object. It is in this way that you get the Tree View to display all levels of your hierarchical data structure. Three Levels in a Tree View Now let’s expand upon this concept and use three levels in our Tree View (Figure 4). This Tree View shows that you now have EmployeeTypes at the top of the tree, followed by a small set of employees that themselves manage employees. This means that the EmployeeType class has a collection of Employee objects. Each Employee class has a collection of Employee objects as well. Figure 4: When using 3 levels in your TreeView you will have 2 Hierarchical Data Templates and 1 Data Template. The EmployeeType class has not changed at all from our previous example. However, the Employee class now has one additional property as shown below: public class Employee{  public Employee(string name)  {    Name = name;    ManagedEmployees = new List<Employee>();  }   public string Name { get; set; }  public List<Employee> ManagedEmployees { get; set; }} The next thing that changes in our code is the EmployeeTypes class. The constructor now needs additional code to create a list of managed employees. Below is the new code. public class EmployeeTypes : List<EmployeeType>{  public EmployeeTypes()  {    EmployeeType type;    Employee emp;    Employee managed;     type = new EmployeeType("Manager");    emp = new Employee("Michael");    managed = new Employee("John");    emp.ManagedEmployees.Add(managed);    managed = new Employee("Tim");    emp.ManagedEmployees.Add(managed);    type.Employees.Add(emp);     emp = new Employee("Paul");    managed = new Employee("Michael");    emp.ManagedEmployees.Add(managed);    managed = new Employee("Sara");    emp.ManagedEmployees.Add(managed);    type.Employees.Add(emp);    this.Add(type);     type = new EmployeeType("Project Managers");    type.Employees.Add(new Employee("Tim"));    type.Employees.Add(new Employee("John"));    type.Employees.Add(new Employee("David"));    this.Add(type);  }} Now that you have all of the data built in your classes, you are now ready to hook up this three-level structure to your Tree View. Figure 5 shows the complete XAML needed to hook up your three-level Tree View. You can see in the XAML that there are now two Hierarchical Data Templates and one Data Template. Again you list the Data Template first since that is the lowest level in your Tree View. The next Hierarchical Data Template listed is the next level up from the lowest level, and finally you have a Hierarchical Data Template for the first level in your tree. You need to work your way from the bottom up when creating your Tree View hierarchy. XAML is processed from the top down, so if you attempt to reference a XAML key name that is below where you are referencing it from, you will get a runtime error. Figure 5: For three levels in a Tree View you will need two Hierarchical Data Templates and one Data Template. Each Hierarchical Data Template uses the previous template as its ItemTemplate. The ItemsSource of each Hierarchical Data Template is used to feed the data to the previous template. This is probably the most confusing part about working with the Tree View control. You are expecting the content of the current Hierarchical Data Template to use the properties set in the ItemsSource property of that template. But you need to look to the template lower down in the XAML to see the source of the data as shown in Figure 6. Figure 6: The properties you use within the Content of a template come from the ItemsSource of the next template in the resources section. Summary Understanding how to put together your hierarchy in a Tree View is simple once you understand that you need to work from the bottom up. Start with the bottom node in your Tree View and determine what that will look like and where the data will come from. You then build the next Hierarchical Data Template to feed the data to the previous template you created. You keep doing this for each level in your Tree View until you get to the last level. The data for that last Hierarchical Data Template comes from the ItemsSource in the Tree View itself. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “Silverlight TreeView with Multiple Levels” from the drop down list.

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  • LLBLGen Pro feature highlights: automatic element name construction

    - by FransBouma
    (This post is part of a series of posts about features of the LLBLGen Pro system) One of the things one might take for granted but which has a huge impact on the time spent in an entity modeling environment is the way the system creates names for elements out of the information provided, in short: automatic element name construction. Element names are created in both directions of modeling: database first and model first and the more names the system can create for you without you having to rename them, the better. LLBLGen Pro has a rich, fine grained system for creating element names out of the meta-data available, which I'll describe more in detail below. First the model element related element naming features are highlighted, in the section Automatic model element naming features and after that I'll go more into detail about the relational model element naming features LLBLGen Pro has to offer in the section Automatic relational model element naming features. Automatic model element naming features When working database first, the element names in the model, e.g. entity names, entity field names and so on, are in general determined from the relational model element (e.g. table, table field) they're mapped on, as the model elements are reverse engineered from these relational model elements. It doesn't take rocket science to automatically name an entity Customer if the entity was created after reverse engineering a table named Customer. It gets a little trickier when the entity which was created by reverse engineering a table called TBL_ORDER_LINES has to be named 'OrderLine' automatically. Automatic model element naming also takes into effect with model first development, where some settings are used to provide you with a default name, e.g. in the case of navigator name creation when you create a new relationship. The features below are available to you in the Project Settings. Open Project Settings on a loaded project and navigate to Conventions -> Element Name Construction. Strippers! The above example 'TBL_ORDER_LINES' shows that some parts of the table name might not be needed for name creation, in this case the 'TBL_' prefix. Some 'brilliant' DBAs even add suffixes to table names, fragments you might not want to appear in the entity names. LLBLGen Pro offers you to define both prefix and suffix fragments to strip off of table, view, stored procedure, parameter, table field and view field names. In the example above, the fragment 'TBL_' is a good candidate for such a strip pattern. You can specify more than one pattern for e.g. the table prefix strip pattern, so even a really messy schema can still be used to produce clean names. Underscores Be Gone Another thing you might get rid of are underscores. After all, most naming schemes for entities and their classes use PasCal casing rules and don't allow for underscores to appear. LLBLGen Pro can automatically strip out underscores for you. It's an optional feature, so if you like the underscores, you're not forced to see them go: LLBLGen Pro will leave them alone when ordered to to so. PasCal everywhere... or not, your call LLBLGen Pro can automatically PasCal case names on word breaks. It determines word breaks in a couple of ways: a space marks a word break, an underscore marks a word break and a case difference marks a word break. It will remove spaces in all cases, and based on the underscore removal setting, keep or remove the underscores, and upper-case the first character of a word break fragment, and lower case the rest. Say, we keep the defaults, which is remove underscores and PasCal case always and strip the TBL_ fragment, we get with our example TBL_ORDER_LINES, after stripping TBL_ from the table name two word fragments: ORDER and LINES. The underscores are removed, the first character of each fragment is upper-cased, the rest lower-cased, so this results in OrderLines. Almost there! Pluralization and Singularization In general entity names are singular, like Customer or OrderLine so LLBLGen Pro offers a way to singularize the names. This will convert OrderLines, the result we got after the PasCal casing functionality, into OrderLine, exactly what we're after. Show me the patterns! There are other situations in which you want more flexibility. Say, you have an entity Customer and an entity Order and there's a foreign key constraint defined from the target of Order and the target of Customer. This foreign key constraint results in a 1:n relationship between the entities Customer and Order. A relationship has navigators mapped onto the relationship in both entities the relationship is between. For this particular relationship we'd like to have Customer as navigator in Order and Orders as navigator in Customer, so the relationship becomes Customer.Orders 1:n Order.Customer. To control the naming of these navigators for the various relationship types, LLBLGen Pro defines a set of patterns which allow you, using macros, to define how the auto-created navigator names will look like. For example, if you rather have Customer.OrderCollection, you can do so, by changing the pattern from {$EndEntityName$P} to {$EndEntityName}Collection. The $P directive makes sure the name is pluralized, which is not what you want if you're going for <EntityName>Collection, hence it's removed. When working model first, it's a given you'll create foreign key fields along the way when you define relationships. For example, you've defined two entities: Customer and Order, and they have their fields setup properly. Now you want to define a relationship between them. This will automatically create a foreign key field in the Order entity, which reflects the value of the PK field in Customer. (No worries if you hate the foreign key fields in your classes, on NHibernate and EF these can be hidden in the generated code if you want to). A specific pattern is available for you to direct LLBLGen Pro how to name this foreign key field. For example, if all your entities have Id as PK field, you might want to have a different name than Id as foreign key field. In our Customer - Order example, you might want to have CustomerId instead as foreign key name in Order. The pattern for foreign key fields gives you that freedom. Abbreviations... make sense of OrdNr and friends I already described word breaks in the PasCal casing paragraph, how they're used for the PasCal casing in the constructed name. Word breaks are used for another neat feature LLBLGen Pro has to offer: abbreviation support. Burt, your friendly DBA in the dungeons below the office has a hate-hate relationship with his keyboard: he can't stand it: typing is something he avoids like the plague. This has resulted in tables and fields which have names which are very short, but also very unreadable. Example: our TBL_ORDER_LINES example has a lovely field called ORD_NR. What you would like to see in your fancy new OrderLine entity mapped onto this table is a field called OrderNumber, not a field called OrdNr. What you also like is to not have to rename that field manually. There are better things to do with your time, after all. LLBLGen Pro has you covered. All it takes is to define some abbreviation - full word pairs and during reverse engineering model elements from tables/views, LLBLGen Pro will take care of the rest. For the ORD_NR field, you need two values: ORD as abbreviation and Order as full word, and NR as abbreviation and Number as full word. LLBLGen Pro will now convert every word fragment found with the word breaks which matches an abbreviation to the given full word. They're case sensitive and can be found in the Project Settings: Navigate to Conventions -> Element Name Construction -> Abbreviations. Automatic relational model element naming features Not everyone works database first: it may very well be the case you start from scratch, or have to add additional tables to an existing database. For these situations, it's key you have the flexibility that you can control the created table names and table fields without any work: let the designer create these names based on the entity model you defined and a set of rules. LLBLGen Pro offers several features in this area, which are described in more detail below. These features are found in Project Settings: navigate to Conventions -> Model First Development. Underscores, welcome back! Not every database is case insensitive, and not every organization requires PasCal cased table/field names, some demand all lower or all uppercase names with underscores at word breaks. Say you create an entity model with an entity called OrderLine. You work with Oracle and your organization requires underscores at word breaks: a table created from OrderLine should be called ORDER_LINE. LLBLGen Pro allows you to do that: with a simple checkbox you can order LLBLGen Pro to insert an underscore at each word break for the type of database you're working with: case sensitive or case insensitive. Checking the checkbox Insert underscore at word break case insensitive dbs will let LLBLGen Pro create a table from the entity called Order_Line. Half-way there, as there are still lower case characters there and you need all caps. No worries, see below Casing directives so everyone can sleep well at night For case sensitive databases and case insensitive databases there is one setting for each of them which controls the casing of the name created from a model element (e.g. a table created from an entity definition using the auto-mapping feature). The settings can have the following values: AsProjectElement, AllUpperCase or AllLowerCase. AsProjectElement is the default, and it keeps the casing as-is. In our example, we need to get all upper case characters, so we select AllUpperCase for the setting for case sensitive databases. This will produce the name ORDER_LINE. Sequence naming after a pattern Some databases support sequences, and using model-first development it's key to have sequences, when needed, to be created automatically and if possible using a name which shows where they're used. Say you have an entity Order and you want to have the PK values be created by the database using a sequence. The database you're using supports sequences (e.g. Oracle) and as you want all numeric PK fields to be sequenced, you have enabled this by the setting Auto assign sequences to integer pks. When you're using LLBLGen Pro's auto-map feature, to create new tables and constraints from the model, it will create a new table, ORDER, based on your settings I previously discussed above, with a PK field ID and it also creates a sequence, SEQ_ORDER, which is auto-assigns to the ID field mapping. The name of the sequence is created by using a pattern, defined in the Model First Development setting Sequence pattern, which uses plain text and macros like with the other patterns previously discussed. Grouping and schemas When you start from scratch, and you're working model first, the tables created by LLBLGen Pro will be in a catalog and / or schema created by LLBLGen Pro as well. If you use LLBLGen Pro's grouping feature, which allows you to group entities and other model elements into groups in the project (described in a future blog post), you might want to have that group name reflected in the schema name the targets of the model elements are in. Say you have a model with a group CRM and a group HRM, both with entities unique for these groups, e.g. Employee in HRM, Customer in CRM. When auto-mapping this model to create tables, you might want to have the table created for Employee in the HRM schema but the table created for Customer in the CRM schema. LLBLGen Pro will do just that when you check the setting Set schema name after group name to true (default). This gives you total control over where what is placed in the database from your model. But I want plural table names... and TBL_ prefixes! For now we follow best practices which suggest singular table names and no prefixes/suffixes for names. Of course that won't keep everyone happy, so we're looking into making it possible to have that in a future version. Conclusion LLBLGen Pro offers a variety of options to let the modeling system do as much work for you as possible. Hopefully you enjoyed this little highlight post and that it has given you new insights in the smaller features available to you in LLBLGen Pro, ones you might not have thought off in the first place. Enjoy!

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  • C#/.NET Fundamentals: Choosing the Right Collection Class

    - by James Michael Hare
    The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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  • SOA Community Newsletter: nouvelle lettre !

    - by mseika
    SOA PARTNER COMMUNITY NEWSLETTERAUGUST 2012 Dear SOA partner community member Have you submitted your feedback on SOA Partner Community Survey 2012? This is the last chance to participate in the survey. We recommend you to complete the survey and help us to improve our SOA Community. Thanks to all attendees and trainers for their participation in the excellent Fusion Middleware Summer Camps held in Lisbon and Munich. I would also like to thank you for the great feedback and the nice reports provided by AMIS Technology Blog & Middleware by Link Consulting. Most of our courses have been overbooked, if you did not get a chance or missed it, we offer a wide range of online training and the course material. Key take-away from the advanced BPM course is to become an expert in ADF. Here is the course from Grant Ronald Learn Advanced ADF online available. The Link Consulting Team became experts in SOA Governance with EAMS and Oracle Enterprise Repository! We always encourage our community members to share their best practices and are very keen to publish it. Please let us know if you want to share your best practices through this medium.We encourage you to make use of the Specialization benefits - this month we are giving an opportunity to Promote Your SOA & BPM Events. Jürgen KressOracle SOA & BPM Partner Adoption EMEA NEW CONTENT Presentations & Training material OFM Summer CampsPromote Your SOA & BPM Events Advanced ADF Online, For Free By Grant BPM 11g Customer Stories & Solution Catalog & Process Accelerators Delivering SOA Governance with EAMS by Link Consulting Team WebLogic Server Provisioning and Patching News from our Partners & CommunityUpdated material by Oracle Connect and Network SOA Blogs SOA on Facebook SOA on LinkedIn SOA on Twitter Mix SOA Forum SOA Workspace PRESENTATIONS & TRAINING MATERIAL OFM SUMMER CAMPS Thanks to all attendees who invested their time and utilized the opportunity to attend the Summer Camps! Due to high demand of our most of the trainings, we had a long waiting list with more numbers of partners who are keen to attend it. We would like to give our special thanks to all trainers, who delivered excellent workshops! Most of the presentations and course material have been posted on our SOA Community Workspaceand WebLogic Community Workspace. You can access the content only if you are a registered community member. To register for the SOA Community please click here. You can register for the WebLogic Community here. To find out the first impressions of the event please visit our Facebook pages:www.facebook.com/WebLogicCommunity &www.facebook.com/soacommunity or Picasa AlbumThanks for the excellent blog posts from AMIS Technology Blog & Middleware by Link Consulting. Let us know if you published a twitter blog on@soacommunity & @wlscommunity. We will be pleased to publish it in our Newsletters. BPM Course Quotes “Its always easy, if you know, what you are doing” - Torsten Winterberg, Opitz“ The best ideas are the ideas from the best” - Filipe Sequeria, Primesoft “Best invest in the education in the last 12 months” - Richard Schaller, IPT “Practice best practice with the best instructor” - Graham Lamond Capgemini “If you have basic BPM knowledge, this is the course to really mater it” - Diogo Henriques Link Consulting “Very good trainers lot of work. Lot of fun as well” - Matthias Gris Workflow Factory “If you like to accelerate in Oracle come to the training to bring it all together” - Marcel van der Glind, Amis ADF Course Quotes "Excellent training, great opportunity to network!" - Frank Houweling, Amis "Lots of fun and good ideas" - Ana Santiago, GFI "Learn ADF, worth it Fusion Apps is the future" - Miguel Delgadillo, STO Consulting "The best way to learn Fusion Middleware from the #1" Alexandro Montantes, STO Consulting "Be advanced to to be the first” - Dimitar Petrov Fadata "Great opportunity to suck all the knowledge out of some very experienced product managers” - Wilfred von der Deijl, The Future Group WebLogic Course Quotes “Oracle trainings are the best” - Pedro Neto Novobas“ "Excellent training, well organized” - Pedro Antunh, Capgemini “This course dives you into Oracle WebLogic giving you a quick start on benefiting from Fusion Apps” - Leonardo Fernandes, Outsystems Additional Quotes “Thanks a lot again for organizing such a great and informative Summer Camp. Both training and networking were organized very professionally. I have gained tons of very useful Info, which will definitely help to increase quality of our future projects.” - Daniel Fasko fss-group.com I didn’t get the chance yesterday to thank you for a most enjoyable and thoroughly educational time I had in Munich over the last few days.” - Jeroen Bakker Ordina “Just to congratulate you on a great event, not only today but also in the previous days of training. As we know, a very good organization and, as a native Portuguese that knows Lisbon very good, a nice choice of places to visit. Looking forward to come again next year.” Pedro Miguel Neto, Novobase PROMOTE YOUR SOA & BPM EVENTS The Partner Event Publisher has just been made available to all SOA & BPM specialized partners in EMEA. Partners now have the opportunity to publish their events to theOracle.com/events site and spread the word on their upcoming live in-person and/or live webcast events. See the demo below and click here to read more information. ADVANCED ADF ONLINE, FOR FREE BY GRANT The second part of the advanced ADF online eCourse is Live now! This covers the advanced topics of region and region interaction as well as getting down and dirty with some of the layout features of ADF Faces, skinning and DVT components. The aim of this course is to give you a self-paced learning aid which covers the more advanced topics of ADF development. The content is developed by Product Management and our Curriculum development teams and is based on advanced training material we have been running internally for about 18 months. We will get started on the next chapter, but in the meantime, please have a look at chapters one and two. Back to top BPM 11G CUSTOMER STORIES & SOLUTION CATALOG & PROCESS ACCELERATORS Stories Everyone loves a good story on planning or implementing a BPM strategy. Everyone wants to hear how it was done before?, what worked?, what was achieved? If you have achieved success with BPM, we are very keen to hear your stories and examples of how your customers use it. We receive lots of requests from people who are thinking of using BPM to solve a specific problem or in combination with a specific technology to talk to someone who has done it before. These stories are invaluable. Drop down the details of anything you think is relevant with a bit of detail and we will follow up on it. As one good deed deserves another, we will do our best to give you stories if you need them to show that where you are going, others have treaded before. Send your stories to us using this e-mail link and we will share them among other like minded people. Solution Catalogue This summer, Oracle is launching a solution catalogue specifically intended for partners. If you have delivered a successful implementation in BPM and think it could be reused and applied again in a similar scenario in the same industry or in a similar environment, then we ware keen to know about it and will add it to the solution catalogue. The solution catalogue will showcase successful BPM solutions both inside and outside Oracle. Be in touch with us on this e-mail link and we will make sure to add your solution. Process AcceleratorsFinally if you have specific processes that you are expert on, you have implemented at a customer and you want to work with us on getting these productised, then we would love to know about it. The process accelerator programme is explained in the most recent SOA/BPM Community Newsletter but again feel free to contact us if you want to get involved. Good luck with BPM and let us know how we can help. Barry O'Reilly Director BPM [email protected] DELIVERING SOA GOVERNANCE WITH EAMS BY LINK CONSULTING TEAM In the last 12 years Link Consulting has been making its presence in specific areas such as Governance and Architecture, both in terms of practices and methodologies, products, know-how and technological expertise. The Enterprise Architecture Management System - Oracle Enterprise Edition (EAMS - OER Edition) is the result of this experience and combines the architecture management solution with OER in order to deliver a product specialized for SOA Governance that gathers the better of two worlds in solution that enables SOA Governance projects, initiatives and programs. Enterprise Architecture Management System Enterprise Architecture Management System (EAMS), is an automation based solution that enables the efficient management of Enterprise Architectures. The solution uses configured enterprise repositories and takes advantages of its features to provide automation capabilities to the users. EAMS provides capabilities to create/customize/analyze repository data, architectural blueprints, reports and analytic charts. Oracle Enterprise Repository Oracle Enterprise Repository (OER) is one of the major and central elements of the Oracle SOA Governance solution. Oracle Enterprise Repository provides the tools to manage and govern the metadata for any type of software asset, from business processes and services to patterns, frameworks, applications, components, and models. OER maps the relationships and inter-dependencies that connect those assets to improve impact analysis, promote and optimize their reuse, and measure their impact on the bottom line. It provides the visibility, feedback, controls, and analytics to keep your SOA on track to deliver business value. The intense focus on automation helps to overcome barriers to SOA adoption and streamline governance throughout the lifecycle. Core capabilities of the OER include: Asset Management Asset Lifecycle Management Usage Tracking Service Discovery Version Management Dependency Analysis Portfolio Management EAMS - OER Edition The solution takes the advantages and features from both products and combines them in a symbiotic tool that enhances the quality of SOA Governance Initiatives and Programs. EAMS is able to produce a vast number of outputs by combining its analytical engine, SOA-specific configurations and the assets in OER and other related tools, catalogs and repositories. The configurations encompass not only the extendable parametrization of the metadata but also fully configurable blueprints, PowerPoint reports, charts and queries. The SOA blueprints The solution comes with a set of predefined architectural representations that help the organization better perceive their SOA landscape. More blueprints can be easily created in order to accommodate the organizations needs in terms of detail, audience and metadata. Charts & Dashboards The solution encompasses a set of predefined charts and dashboards that promote a more agile way to control and explore the assets. Time Based Visualization All representations are time bound, and with EAMS - OER you can truly govern SOA with a complete view of the Past, Present and Future; The solution delivers Gap Analysis, a project oriented approach while taking into consideration the As-Was, As-Is an To-Be. Time based visualization differentiating factors: Extensive automation and maintenance of architectural representations Organization wide solution. Easy access and navigation to and between all architectural artifacts and representations. Flexible meta-model, customization and extensibility capabilities. Lifecycle management and enforcement of the time dimension over all the repository content. Profile based customization. Comprehensive visibility Architectural alignment Friendly and striking user interfaces For more information on EAMS visit us here. For more information on SOA visit us here. WEBLOGIC SERVER PROVISIONING AND PATCHING For access to the Oracle demo systems please visit OPN and talk to your Partner Expert.SOA Suite and BPM Suite runs on WebLogic! We are pleased to announce the availability of a WebLogic Server Management demo that showcases some of the key provisioning and patching capabilities of WebLogic Server Management Pack Enterprise Edition (EE). To learn more about these features - as well as other features of the pack - please visit the pack's saleskit page.Demo Highlights The demo showcases the following capabilities: Patching Oracle WebLogic Servers Standardizing WebLogic Server Patch Rollouts Creating a WebLogic Domain Provisioning Profile Cloning a WebLogic Domain from a Provisioning Profile Deploying a Java EE Application Scaling Out an Oracle WebLogic Cluster Demo Instructions Go to the DSS website for Oracle Partners. On the Standard Demo Launchpad page, under the “Software Lifecycle Automation” section, click on the link “EM Cloud Control 12c WLS Provisioning and Patching” (tagged as “NEW”). Specific demo launchpad page contains a link to the detailed demo script with instructions on how to show the demo.

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  • VS 2012 Code Review &ndash; Before Check In OR After Check In?

    - by Tarun Arora
    “Is Code Review Important and Effective?” There is a consensus across the industry that code review is an effective and practical way to collar code inconsistency and possible defects early in the software development life cycle. Among others some of the advantages of code reviews are, Bugs are found faster Forces developers to write readable code (code that can be read without explanation or introduction!) Optimization methods/tricks/productive programs spread faster Programmers as specialists "evolve" faster It's fun “Code review is systematic examination (often known as peer review) of computer source code. It is intended to find and fix mistakes overlooked in the initial development phase, improving both the overall quality of software and the developers' skills. Reviews are done in various forms such as pair programming, informal walkthroughs, and formal inspections.” Wikipedia No where does the definition mention whether its better to review code before the code has been committed to version control or after the commit has been performed. No matter which side you favour, Visual Studio 2012 allows you to request for a code review both before check in and also request for a review after check in. Let’s weigh the pros and cons of the approaches independently. Code Review Before Check In or Code Review After Check In? Approach 1 – Code Review before Check in Developer completes the code and feels the code quality is appropriate for check in to TFS. The developer raises a code review request to have a second pair of eyes validate if the code abides to the recommended best practices, will not result in any defects due to common coding mistakes and whether any optimizations can be made to improve the code quality.                                             Image 1 – code review before check in Pros Everything that gets committed to source control is reviewed. Minimizes the chances of smelly code making its way into the code base. Decreases the cost of fixing bugs, remember, the earlier you find them, the lesser the pain in fixing them. Cons Development Code Freeze – Since the changes aren’t in the source control yet. Further development can only be done off-line. The changes have not been through a CI build, hard to say whether the code abides to all build quality standards. Inconsistent! Cumbersome to track the actual code review process.  Not every change to the code base is worth reviewing, a lot of effort is invested for very little gain. Approach 2 – Code Review after Check in Developer checks in, random code reviews are performed on the checked in code.                                                      Image 2 – Code review after check in Pros The code has already passed the CI build and run through any code analysis plug ins you may have running on the build server. Instruct the developer to ensure ZERO fx cop, style cop and static code analysis before check in. Code is cleaner and smell free even before the code review. No Offline development, developers can continue to develop against the source control. Cons Bad code can easily make its way into the code base. Since the review take place much later in the cycle, the cost of fixing issues can prove to be much higher. Approach 3 – Hybrid Approach The community advocates a more hybrid approach, a blend of tooling and human accountability quotient.                                                               Image 3 – Hybrid Approach 1. Code review high impact check ins. It is not possible to review everything, by setting up code review check in policies you can end up slowing your team. More over, the code that you are reviewing before check in hasn't even been through a green CI build either. 2. Tooling. Let the tooling work for you. By running static analysis, fx cop, style cop and other plug ins on the build agent, you can identify the real issues that in my opinion can't possibly be identified using human reviews. Configure the tooling to report back top 10 issues every day. Mandate the manual code review of individuals who keep making it to this list of shame more often. 3. During Merge. I would prefer eliminating some of the other code issues during merge from Main branch to the release branch. In a scrum project this is still easier because cheery picking the merges is a possibility and the size of code being reviewed is still limited. Let the tooling work for you, if some one breaks the CI build often, put them on a gated check in build course until you see improvement. If some one appears on the top 10 list of shame generated via the build then ensure that all their code is reviewed till you see improvement. At the end of the day, the goal is to ensure that the code being delivered is top quality. By enforcing a code review before any check in, you force the developer to work offline or stay put till the review is complete. What do the experts say? So I asked a few expects what they thought of “Code Review quality gate before Checking in code?" Terje Sandstrom | Microsoft ALM MVP You mean a review quality gate BEFORE checking in code????? That would mean a lot of code staying either local or in shelvesets, and not even been through a CI build, and a green CI build being the main criteria for going further, f.e. to the review state. I would not like code laying around with no checkin’s. Having a requirement that code is checked in small pieces, 4-8 hours work max, and AT LEAST daily checkins, a manual code review comes second down the lane. I would expect review quality gates to happen before merging back to main, or before merging to release.  But that would all be on checked-in code.  Branching is absolutely one way to ease the pain.   Another way we are using is automatic quality builds, running metrics, coverage, static code analysis.  Unfortunately it takes some time, would be great to be on CI’s – but…., so it’s done scheduled every night. Based on this we get, among other stuff,  top 10 lists of suspicious code, which is then subjected to reviews.  If a person seems to be very popular on these top 10 lists, we subject every check in from that person to a review for a period. That normally helps.   None of the clients I have can afford to have every checkin reviewed, so we need to find ways around it. I don’t disagree with the nicety of having all the code reviewed, but I find it hard to find those resources in today’s enterprises. David V. Corbin | Visual Studio ALM Ranger I tend to agree with both sides. I hate having code that is not checked in, but at the same time hate having “bad” code in the repository. I have found that branching is one approach to solving this dilemma. Code is checked into the private/feature branch before the review, but is not merged over to the “official” branch until after the review. I advocate both, depending on circumstance (especially team dynamics)   - The “pre-checkin” is usually for elements that may impact the project as a whole. Think of it as another “gate” along with passing unit tests. - The “post-checkin” may very well not be at the changeset level, but correlates to a review at the “user story” level.   Again, this depends on team dynamics in play…. Robert MacLean | Microsoft ALM MVP I do not think there is no right answer for the industry as a whole. In short the question is why do you do reviews? Your question implies risk mitigation, so in low risk areas you can get away with it after check in while in high risk you need to do it before check in. An example is those new to a team or juniors need it much earlier (maybe that is before checkin, maybe that is soon after) than seniors who have shipped twenty sprints on the team. Abhimanyu Singhal | Visual Studio ALM Ranger Depends on per scenario basis. We recommend post check-in reviews when: 1. We don't want to block other checks and processes on manual code reviews. Manual reviews take time, and some pieces may not require manual reviews at all. 2. We need to trace all changes and track history. 3. We have a code promotion strategy/process in place. For risk mitigation, post checkin code can be promoted to Accepted branches. Or can be rejected. Pre Checkin Reviews are used when 1. There is a high risk factor associated 2. Reviewers are generally (most of times) have immediate availability. 3. Team does not have strict tracking needs. Simply speaking, no single process fits all scenarios. You need to select what works best for your team/project. Thomas Schissler | Visual Studio ALM Ranger This is an interesting discussion, I’m right now discussing details about executing code reviews with my teams. I see and understand the aspects you brought in, but there is another side as well, I’d like to point out. 1.) If you do reviews per check in this is not very practical as a hard rule because this will disturb the flow of the team very often or it will lead to reduce the checkin frequency of the devs which I would not accept. 2.) If you do later reviews, for example if you review PBIs, it is not easy to find out which code you should review. Either you review all changesets associate with the PBI, but then you might review code which has been changed with a later checkin and the dev maybe has already fixed the issue. Or you review the diff of the latest changeset of the PBI with the first but then you might also review changes of other PBIs. Jakob Leander | Sr. Director, Avanade In my experience, manual code review: 1. Does not get done and at the very least does not get redone after changes (regardless of intentions at start of project) 2. When a project actually do it, they often do not do it right away = errors pile up 3. Requires a lot of time discussing/defining the standard and for the team to learn it However code review is very important since e.g. even small memory leaks in a high volume web solution have big consequences In the last years I have advocated following approach for code review - Architects up front do “at least one best practice example” of each type of component and tell the team. Copy from this one. This should include error handling, logging, security etc. - Dev lead on project continuously browse code to validate that the best practices are used. Especially that patterns etc. are not broken. You can do this formally after each sprint/iteration if you want. Once this is validated it is unlikely to “go bad” even during later code changes Agree with customer to rely on static code analysis from Visual Studio as the one and only coding standard. This has HUUGE benefits - You can easily tweak to reach the level you desire together with customer - It is easy to measure for both developers/management - It is 100% consistent across code base - It gets validated all the time so you never end up getting hammered by a customer review in the end - It is easy to tell the developer that you do not want code back unless it has zero errors = minimize communication You need to track this at least during nightly builds and make sure team sees total # issues. Do not allow #issues it to grow uncontrolled. On the project I run I require code analysis to have run on code before checkin (checkin rule). This means -  You have to have clean compile (or CA wont run) so this is extra benefit = very few broken builds - You can change a few of the rules to compile as errors instead of warnings. I often do this for “missing dispose” issues which you REALLY do not want in your app Tip: Place your custom CA rules files as part of solution. That  way it works when you do branching etc. (path to CA file is relative in VS) Some may argue that CA is not as good as manual inspection. But since manual inspection in reality suffers from the 3 issues in start it is IMO a MUCH better (and much cheaper) approach from helicopter perspective Tirthankar Dutta | Director, Avanade I think code review should be run both before and after check ins. There are some code metrics that are meant to be run on the entire codebase … Also, especially on multi-site projects, one should strive to architect in a way that lets men manage the framework while boys write the repetitive code… scales very well with the need to review less by containment and imposing architectural restrictions to emphasise the design. Bruno Capuano | Microsoft ALM MVP For code reviews (means peer reviews) in distributed team I use http://www.vsanywhere.com/default.aspx  David Jobling | Global Sr. Director, Avanade Peer review is the only way to scale and its a great practice for all in the team to learn to perform and accept. In my experience you soon learn who's code to watch more than others and tune the attention. Mikkel Toudal Kristiansen | Manager, Avanade If you have several branches in your code base, you will need to merge often. This requires manual merging, when a file has been changed in both branches. It offers a good opportunity to actually review to changed code. So my advice is: Merging between branches should be done as often as possible, it should be done by a senior developer, and he/she should perform a full code review of the code being merged. As for detecting architectural smells and code smells creeping into the code base, one really good third party tools exist: Ndepend (http://www.ndepend.com/, for static code analysis of the current state of the code base). You could also consider adding StyleCop to the solution. Jesse Houwing | Visual Studio ALM Ranger I gave a presentation on this subject on the TechDays conference in NL last year. See my presentation and slides here (talk in Dutch, but English presentation): http://blog.jessehouwing.nl/2012/03/did-you-miss-my-techdaysnl-talk-on-code.html  I’d like to add a few more points: - Before/After checking is mostly a trust issue. If you have a team that does diligent peer reviews and regularly talk/sit together or peer review, there’s no need to enforce a before-checkin policy. The peer peer-programming and regular feedback during development can take care of most of the review requirements as long as the team isn’t under stress. - Under stress, enforce pre-checkin reviews, it might sound strange, if you’re already under time or budgetary constraints, but it is under such conditions most real issues start to be created or pile up. - Use tools to catch most common errors, Code Analysis/FxCop was already mentioned. HP Fortify, Resharper, Coderush etc can help you there. There are also a lot of 3rd party rules you can add to Code Analysis. I’ve written a few myself (http://fccopcontrib.codeplex.com) and various teams from Microsoft have added their own rules (MSOCAF for SharePoint, WSSF for WCF). For common errors that keep cropping up, see if you can define a rule. It’s much easier. But more importantly make sure you have a good help page explaining *WHY* it's wrong. If you have small feature or developer branches/shelvesets, you might want to review pre-merge. It’s still better to do peer reviews and peer programming, but the most important thing is that bad quality code doesn’t make it into the important branch. So my philosophy: - Use tooling as much as possible. - Make sure the team understands the tooling and the importance of the things it flags. It’s too easy to just click suppress all to ignore the warnings. - Under stress, tighten process, it’s under stress that the problems of late reviews will really surface - Most importantly if you do reviews do them as early as possible, but never later than needed. In other words, pre-checkin/post checking doesn’t really matter, as long as the review is done before the code is released. It’ll just be much more expensive to fix any review outcomes the later you find them. --- I would love to hear what you think!

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