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• Using Unity – Part 1

  - by nmarun

  I have been going through implementing some IoC pattern using Unity and so I decided to share my learnings (I know that’s not an English word, but you get the point). Ok, so I have an ASP.net project named ProductWeb and a class library called ProductModel. In the model library, I have a class called Product: 1: public class Product 2: { 3: public string Name { get; set; } 4: public string Description { get; set; } 5:  6: public Product() 7: { 8: Name = "iPad"; 9: Description = "Not just a reader!"; 10: } 11:  12: public string WriteProductDetails() 13: { 14: return string.Format("Name: {0} Description: {1}", Name, Description); 15: } 16: } In the Page_Load event of the default.aspx, I’ll need something like: 1: Product product = new Product(); 2: productDetailsLabel.Text = product.WriteProductDetails(); Now, let’s go ‘Unity’fy this application. I assume you have all the bits for the pattern. If not, get it from here. I found this schematic representation of Unity pattern from the above link. This image might not make much sense to you now, but as we proceed, things will get better. The first step to implement the Inversion of Control pattern is to create interfaces that your types will implement. An IProduct interface is added to the ProductModel project. 1: public interface IProduct 2: { 3: string WriteProductDetails(); 4: } Let’s make our Product class to implement the IProduct interface. The application will compile and run as before despite the changes made. Add the following references to your web project: Microsoft.Practices.Unity Microsoft.Practices.Unity.Configuration Microsoft.Practices.Unity.StaticFactory Microsoft.Practices.ObjectBuilder2 We need to add a few lines to the web.config file. The line below tells what version of Unity pattern we’ll be using. 1: <configSections> 2: <section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration, Version=1.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> 3: </configSections> Add another block with the same name as the section name declared above – ‘unity’. 1: <unity> 2: <typeAliases> 3: <!--Custom object types--> 4: <typeAlias alias="IProduct" type="ProductModel.IProduct, ProductModel"/> 5: <typeAlias alias="Product" type="ProductModel.Product, ProductModel"/> 6: </typeAliases> 7: <containers> 8: <container name="unityContainer"> 9: <types> 10: <type type="IProduct" mapTo="Product"/> 11: </types> 12: </container> 13: </containers> 14: </unity> From the Unity Configuration schematic shown above, you see that the ‘unity’ block has a ‘typeAliases’ and a ‘containers’ segment. The typeAlias element gives a ‘short-name’ for a type. This ‘short-name’ can be used to point to this type any where in the configuration file (web.config in our case, but all this information could be coming from an external xml file as well). The container element holds all the mapping information. This container is referenced through its name attribute in the code and you can have multiple of these container elements in the containers segment. The ‘type’ element in line 10 basically says: ‘When Unity requests to resolve the alias IProduct, return an instance of whatever the short-name of Product points to’. This is the most basic piece of Unity pattern and all of this is accomplished purely through configuration. So, in future you have a change in your model, all you need to do is - implement IProduct on the new model class and - either add a typeAlias for the new type and point the mapTo attribute to the new alias declared - or modify the mapTo attribute of the type element to point to the new alias (as the case may be). Now for the calling code. It’s a good idea to store your unity container details in the Application cache, as this is rarely bound to change and also adds for better performance. The Global.asax.cs file comes for our rescue: 1: protected void Application_Start(object sender, EventArgs e) 2: { 3: // create and populate a new Unity container from configuration 4: IUnityContainer unityContainer = new UnityContainer(); 5: UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity"); 6: section.Containers["unityContainer"].Configure(unityContainer); 7: Application["UnityContainer"] = unityContainer; 8: } 9:  10: protected void Application_End(object sender, EventArgs e) 11: { 12: Application["UnityContainer"] = null; 13: } All this says is: create an instance of UnityContainer() and read the ‘unity’ section from the configSections segment of the web.config file. Then get the container named ‘unityContainer’ and store it in the Application cache. In my code-behind file, I’ll make use of this UnityContainer to create an instance of the Product type. 1: public partial class _Default : Page 2: { 3: private IUnityContainer unityContainer; 4: protected void Page_Load(object sender, EventArgs e) 5: { 6: unityContainer = Application["UnityContainer"] as IUnityContainer; 7: if (unityContainer == null) 8: { 9: productDetailsLabel.Text = "ERROR: Unity Container not populated in Global.asax.<p />"; 10: } 11: else 12: { 13: IProduct productInstance = unityContainer.Resolve<IProduct>(); 14: productDetailsLabel.Text = productInstance.WriteProductDetails(); 15: } 16: } 17: } Looking the ‘else’ block, I’m asking the unityContainer object to resolve the IProduct type. All this does, is to look at the matching type in the container, read its mapTo attribute value, get the full name from the alias and create an instance of the Product class. Fabulous!! I’ll go more in detail in the next blog. The code for this blog can be found here.

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• Using Unity – Part 3

  - by nmarun

  The previous blog was about registering and invoking different types dynamically. In this one I’d like to show how Unity manages/disposes the instances – say hello to Lifetime Managers. When a type gets registered, either through the config file or when RegisterType method is explicitly called, the default behavior is that the container uses a transient lifetime manager. In other words, the unity container creates a new instance of the type when Resolve or ResolveAll method is called. Whereas, when you register an existing object using the RegisterInstance method, the container uses a container controlled lifetime manager - a singleton pattern. It does this by storing the reference of the object and that means so as long as the container is ‘alive’, your registered instance does not go out of scope and will be disposed only after the container either goes out of scope or when the code explicitly disposes the container. Let’s see how we can use these and test if something is a singleton or a transient instance. Continuing on the same solution used in the previous blogs, I have made the following changes: First is to add typeAlias elements for TransientLifetimeManager type: 1: <typeAlias alias="transient" type="Microsoft.Practices.Unity.TransientLifetimeManager, Microsoft.Practices.Unity"/> You then need to tell what type(s) you want to be transient by nature: 1: <type type="IProduct" mapTo="Product2"> 2: <lifetime type="transient" /> 3: </type> 4: <!--<type type="IProduct" mapTo="Product2" />--> The lifetime element’s type attribute matches with the alias attribute of the typeAlias element. Now since ‘transient’ is the default behavior, you can have a concise version of the same as line 4 shows. Also note that I’ve changed the mapTo attribute from ‘Product’ to ‘Product2’. I’ve done this to help understand the transient nature of the instance of the type Product2. By making this change, you are basically saying when a type of IProduct needs to be resolved, Unity should create an instance of Product2 by default. 1: public string WriteProductDetails() 2: { 3: return string.Format("Name: {0}<br/>Category: {1}<br/>Mfg Date: {2}<br/>Hash Code: {3}", 4: Name, Category, MfgDate.ToString("MM/dd/yyyy hh:mm:ss tt"), GetHashCode()); 5: } Again, the above change is purely for the purpose of making the example more clear to understand. The display will show the full date and also displays the hash code of the current instance. The GetHashCode() method returns an integer when an instance gets created – a new integer for every instance. When you run the application, you’ll see something like the below: Now when you click on the ‘Get Product2 Instance’ button, you’ll see that the Mfg Date (which is set in the constructor) and the Hash Code are different from the one created on page load. This proves to us that a new instance is created every single time. To make this a singleton, we need to add a type alias for the ContainerControlledLifetimeManager class and then change the type attribute of the lifetime element to singleton. 1: <typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity"/> 2: ... 3: <type type="IProduct" mapTo="Product2"> 4: <lifetime type="singleton" /> 5: </type> Running the application now gets me the following output: Click on the button below and you’ll see that the Mfg Date and the Hash code remain unchanged => the unity container is storing the reference the first time it is created and then returns the same instance every time the type needs to be resolved. Digging more deeper into this, Unity provides more than the two lifetime managers. ExternallyControlledLifetimeManager – maintains a weak reference to type mappings and instances. Unity returns the same instance as long as the some code is holding a strong reference to this instance. For this, you need: 1: <typeAlias alias="external" type="Microsoft.Practices.Unity.ExternallyControlledLifetimeManager, Microsoft.Practices.Unity"/> 2: ... 3: <type type="IProduct" mapTo="Product2"> 4: <lifetime type="external" /> 5: </type> PerThreadLifetimeManager – Unity returns a unique instance of an object for each thread – so this effectively is a singleton behavior on a  per-thread basis. 1: <typeAlias alias="perThread" type="Microsoft.Practices.Unity.PerThreadLifetimeManager, Microsoft.Practices.Unity"/> 2: ... 3: <type type="IProduct" mapTo="Product2"> 4: <lifetime type="perThread" /> 5: </type> One thing to note about this is that if you use RegisterInstance method to register an existing object, this instance will be returned for every thread, making this a purely singleton behavior. Needless to say, this type of lifetime management is useful in multi-threaded applications (duh!!). I hope this blog provided some basics on lifetime management of objects resolved in Unity and in the next blog, I’ll talk about Injection. Please see the code used here.

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• ASP.NET MVC ‘Extendable-hooks’ – ControllerActionInvoker class

  - by nmarun

  There’s a class ControllerActionInvoker in ASP.NET MVC. This can be used as one of an hook-points to allow customization of your application. Watching Brad Wilsons’ Advanced MP3 from MVC Conf inspired me to write about this class. What MSDN says: “Represents a class that is responsible for invoking the action methods of a controller.” Well if MSDN says it, I think I can instill a fair amount of confidence into what the class does. But just to get to the details, I also looked into the source code for MVC. Seems like the base class Controller is where an IActionInvoker is initialized: 1: protected virtual IActionInvoker CreateActionInvoker() { 2: return new ControllerActionInvoker(); 3: } In the ControllerActionInvoker (the O-O-B behavior), there are different ‘versions’ of InvokeActionMethod() method that actually call the action method in question and return an instance of type ActionResult. 1: protected virtual ActionResult InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary<string, object> parameters) { 2: object returnValue = actionDescriptor.Execute(controllerContext, parameters); 3: ActionResult result = CreateActionResult(controllerContext, actionDescriptor, returnValue); 4: return result; 5: } I guess that’s enough on the ‘behind-the-screens’ of this class. Let’s see how we can use this class to hook-up extensions. Say I have a requirement that the user should be able to get different renderings of the same output, like html, xml, json, csv and so on. The user will type-in the output format in the url and should the get result accordingly. For example: http://site.com/RenderAs/ – renders the default way (the razor view) http://site.com/RenderAs/xml http://site.com/RenderAs/csv … and so on where RenderAs is my controller. There are many ways of doing this and I’m using a custom ControllerActionInvoker class (even though this might not be the best way to accomplish this). For this, my one and only route in the Global.asax.cs is: 1: routes.MapRoute("RenderAsRoute", "RenderAs/{outputType}", 2: new {controller = "RenderAs", action = "Index", outputType = ""}); Here the controller name is ‘RenderAsController’ and the action that’ll get called (always) is the Index action. The outputType parameter will map to the type of output requested by the user (xml, csv…). I intend to display a list of food items for this example. 1: public class Item 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: public Cuisine Cuisine { get; set; } 6: } 7:  8: public class Cuisine 9: { 10: public int CuisineId { get; set; } 11: public string Name { get; set; } 12: } Coming to my ‘RenderAsController’ class. I generate an IList<Item> to represent my model. 1: private static IList<Item> GetItems() 2: { 3: Cuisine cuisine = new Cuisine { CuisineId = 1, Name = "Italian" }; 4: Item item = new Item { Id = 1, Name = "Lasagna", Cuisine = cuisine }; 5: IList<Item> items = new List<Item> { item }; 6: item = new Item {Id = 2, Name = "Pasta", Cuisine = cuisine}; 7: items.Add(item); 8: //... 9: return items; 10: } My action method looks like 1: public IList<Item> Index(string outputType) 2: { 3: return GetItems(); 4: } There are two things that stand out in this action method. The first and the most obvious one being that the return type is not of type ActionResult (or one of its derivatives). Instead I’m passing the type of the model itself (IList<Item> in this case). We’ll convert this to some type of an ActionResult in our custom controller action invoker class later. The second thing (a little subtle) is that I’m not doing anything with the outputType value that is passed on to this action method. This value will be in the RouteData dictionary and we’ll use this in our custom invoker class as well. It’s time to hook up our invoker class. First, I’ll override the Initialize() method of my RenderAsController class. 1: protected override void Initialize(RequestContext requestContext) 2: { 3: base.Initialize(requestContext); 4: string outputType = string.Empty; 5:  6: // read the outputType from the RouteData dictionary 7: if (requestContext.RouteData.Values["outputType"] != null) 8: { 9: outputType = requestContext.RouteData.Values["outputType"].ToString(); 10: } 11:  12: // my custom invoker class 13: ActionInvoker = new ContentRendererActionInvoker(outputType); 14: } Coming to the main part of the discussion – the ContentRendererActionInvoker class: 1: public class ContentRendererActionInvoker : ControllerActionInvoker 2: { 3: private readonly string _outputType; 4:  5: public ContentRendererActionInvoker(string outputType) 6: { 7: _outputType = outputType.ToLower(); 8: } 9: //... 10: } So the outputType value that was read from the RouteData, which was passed in from the url, is being set here in  a private field. Moving to the crux of this article, I now override the CreateActionResult method. 1: protected override ActionResult CreateActionResult(ControllerContext controllerContext, ActionDescriptor actionDescriptor, object actionReturnValue) 2: { 3: if (actionReturnValue == null) 4: return new EmptyResult(); 5:  6: ActionResult result = actionReturnValue as ActionResult; 7: if (result != null) 8: return result; 9:  10: // This is where the magic happens 11: // Depending on the value in the _outputType field, 12: // return an appropriate ActionResult 13: switch (_outputType) 14: { 15: case "json": 16: { 17: JavaScriptSerializer serializer = new JavaScriptSerializer(); 18: string json = serializer.Serialize(actionReturnValue); 19: return new ContentResult { Content = json, ContentType = "application/json" }; 20: } 21: case "xml": 22: { 23: XmlSerializer serializer = new XmlSerializer(actionReturnValue.GetType()); 24: using (StringWriter writer = new StringWriter()) 25: { 26: serializer.Serialize(writer, actionReturnValue); 27: return new ContentResult { Content = writer.ToString(), ContentType = "text/xml" }; 28: } 29: } 30: case "csv": 31: controllerContext.HttpContext.Response.AddHeader("Content-Disposition", "attachment; filename=items.csv"); 32: return new ContentResult 33: { 34: Content = ToCsv(actionReturnValue as IList<Item>), 35: ContentType = "application/ms-excel" 36: }; 37: case "pdf": 38: string filePath = controllerContext.HttpContext.Server.MapPath("~/items.pdf"); 39: controllerContext.HttpContext.Response.AddHeader("content-disposition", 40: "attachment; filename=items.pdf"); 41: ToPdf(actionReturnValue as IList<Item>, filePath); 42: return new FileContentResult(StreamFile(filePath), "application/pdf"); 43:  44: default: 45: controllerContext.Controller.ViewData.Model = actionReturnValue; 46: return new ViewResult 47: { 48: TempData = controllerContext.Controller.TempData, 49: ViewData = controllerContext.Controller.ViewData 50: }; 51: } 52: } A big method there! The hook I was talking about kinda above actually is here. This is where different kinds / formats of output get returned based on the output type requested in the url. When the _outputType is not set (string.Empty as set in the Global.asax.cs file), the razor view gets rendered (lines 45-50). This is the default behavior in most MVC applications where-in a view (webform/razor) gets rendered on the browser. As you see here, this gets returned as a ViewResult. But then, for an outputType of json/xml/csv, a ContentResult gets returned, while for pdf, a FileContentResult is returned. Here are how the different kinds of output look like: This is how we can leverage this feature of ASP.NET MVC to developer a better application. I’ve used the iTextSharp library to convert to a pdf format. Mike gives quite a bit of detail regarding this library here. You can download the sample code here. (You’ll get an option to download once you open the link). Verdict: Hot chocolate: $3; Reebok shoes: $50; Your first car: $3000; Being able to extend a web application: Priceless.

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• ASP.NET MVC 2 RTM Unit Tests not compiling

  - by nmarun

  I found something weird this time when it came to ASP.NET MVC 2 release. A very handful of people ‘made noise’ about the release.. at least on the asp.net blog site, usually there’s a big ‘WOOHAA… <something> is released’, kind of a thing. Hmm… but here’s the reason I’m writing this post. I’m not sure how many of you read the release notes before downloading the version.. I did, I did, I did. Now there’s a ‘Known issues’ section in the document and I’m quoting the text as is from this section: Unit test project does not contain reference to ASP.NET MVC 2 project: If the Solution Explorer window is hidden in Visual Studio, when you create a new ASP.NET MVC 2 Web application project and you select the option Yes, create a unit test project in the Create Unit Test Project dialog box, the unit test project is created but does not have a reference to the associated ASP.NET MVC 2 project. When you build the solution, Visual Studio will display compilation errors and the unit tests will not run. There are two workarounds. The first workaround is to make sure that the Solution Explorer is displayed when you create a new ASP.NET MVC 2 Web application project. If you prefer to keep Solution Explorer hidden, the second workaround is to manually add a project reference from the unit test project to the ASP.NET MVC 2 project. This definitely looks like a bug to me and see below for a visual: At the top right corner you’ll see that the Solution Explorer is set to auto hide and there’s no reference for the TestMvc2 project and that is the reason we get compilation errors without even writing a single line of code. So thanks to <VeryBigFont>ME</VeryBigFont> and <VerySmallFont>Microsoft</VerySmallFont>) , we’ve shown the world how to resolve a major issue and to live in Peace with the rest of humanity!

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• LINQ – TakeWhile and SkipWhile methods

  - by nmarun

  I happened to read about these methods on Vikram's blog and tried testing it. Somehow when I saw the output, things did not seem to add up right. I’m writing this blog to show the actual workings of these methods. Let’s take the same example as showing in Vikram’s blog and I’ll build around it. 1: int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 2:  3: foreach(var number in numbers.TakeWhile(n => n < 7)) 4: { 5: Console.WriteLine(number); 6: } Now, the way I (incorrectly) read the upper bound condition in the foreach loop was: ‘Give me all numbers that pass the condition of n<7’. So I was expecting the answer to be: 5, 4, 1, 3, 2, 0. But when I run the application, I see only: 5, 4, 1,3. Turns out I was wrong (happens at least once a day). The documentation on the method says ‘Returns elements from a sequence as long as a specified condition is true. To show in code, my interpretation was the below code’: 1: foreach (var number in numbers) 2: { 3: if (number < 7) 4: { 5: Console.WriteLine(number); 6: } 7: } But the actual implementation is: 1: foreach(var number in numbers) 2: { 3: if(number < 7) 4: { 5: Console.WriteLine(number); 6: break; 7: } 8: } So there it is, another situation where one simple word makes a difference of a whole world. The SkipWhile method has been implemented in a similar way – ‘Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements’ and not ‘Bypasses elements in a sequence where a specified condition is true and then returns the remaining elements’. (Subtle.. very very subtle). It’s feels strange saying this, but hope very few require to read this article to understand these methods.

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• Using Unity – Part 2

  - by nmarun

  In the first part of this series, we created a simple project and learned how to implement IoC pattern using Unity. In this one, I’ll show how you can instantiate other types that implement our IProduct interface. One place where this one would want to use this feature is to create mock types for testing purposes. Alright, let’s dig in. I added another class – Product2.cs  to the ProductModel project. 1: public class Product2 : IProduct 2: { 3: public string Name { get; set;} 4: public Category Category { get; set; } 5: public DateTime MfgDate { get;set; } 6:  7: public Product2() 8: { 9: Name = "Canon Digital Rebel XTi"; 10: Category = new Category {Name = "Electronics", SubCategoryName = "Digital Cameras"}; 11: MfgDate = DateTime.Now; 12: } 13:  14: public string WriteProductDetails() 15: { 16: return string.Format("Name: {0}<br/>Category: {1}<br/>Mfg Date: {2}", 17: Name, Category, MfgDate.ToShortDateString()); 18: } 19: } Highlights of this class are that it implements IProduct interface and it has some different properties than the Product class. The Category class looks like below: 1: public class Category 2: { 3: public string Name { get; set; } 4: public string SubCategoryName { get; set; } 5:  6: public override string ToString() 7: { 8: return string.Format("{0} - {1}", Name, SubCategoryName); 9: } 10: } We’ll go to our web.config file to add the configuration information about this new class – Product2 that we created. Let’s first add a typeAlias element. 1: <typeAlias alias="Product2" type="ProductModel.Product2, ProductModel"/> That’s all that is needed for us to get an instance of Product2 in our application. I have a new button added to the .aspx page and the click event of this button is where all the magic happens: 1: private IUnityContainer unityContainer; 2: protected void Page_Load(object sender, EventArgs e) 3: { 4: unityContainer = Application["UnityContainer"] as IUnityContainer; 5: 6: if (unityContainer == null) 7: { 8: productDetailsLabel.Text = "ERROR: Unity Container not populated in Global.asax.<p />"; 9: } 10: else 11: { 12: if (!IsPostBack) 13: { 14: IProduct productInstance = unityContainer.Resolve<IProduct>(); 15: productDetailsLabel.Text = productInstance.WriteProductDetails(); 16: } 17: } 18: } 19:  20: protected void Product2Button_Click(object sender, EventArgs e) 21: { 22: unityContainer.RegisterType<IProduct, Product2>(); 23: IProduct product2Instance = unityContainer.Resolve<IProduct>(); 24: productDetailsLabel.Text = product2Instance.WriteProductDetails(); 25: } The unityContainer instance is set in the Page_Load event. Line 22 in the click event of the Product2Button registers a type mapping in the container. In English, this means that when unityContainer tries to resolve for IProduct, it gets an instance of Product2. Once this code runs, following output is rendered: There’s another way of doing this. You can resolve an instance of the requested type with a name from the container. We’ll have to update the container element of our web.config file to include the following: 1: <container name="unityContainer"> 2: <types> 3: <type type="IProduct" mapTo="Product"/> 4: <!-- Named mapping for IProduct to Product --> 5: <type type="IProduct" mapTo="Product" name="LegacyProduct" /> 6: <!-- Named mapping for IProduct to Product2 --> 7: <type type="IProduct" mapTo="Product2" name="NewProduct" /> 8: </types> 9: </container> I’ve added a Dropdownlist and a button to the design page: 1: <asp:DropDownList ID="ModelTypesList" runat="server"> 2: <asp:ListItem Text="Legacy Product" Value="LegacyProduct" /> 3: <asp:ListItem Text="New Product" Value="NewProduct" /> 4: </asp:DropDownList> 5: <br /> 6: <asp:Button ID="SelectedModelButton" Text="Get Selected Instance" runat="server" 7: onclick="SelectedModelButton_Click" /> 1: protected void SelectedModelButton_Click(object sender, EventArgs e) 2: { 3: // get the selected value: LegacyProduct or NewProduct 4: string modelType = ModelTypesList.SelectedValue; 5: // pass the modelType to the Resolve method 6: IProduct customModel = unityContainer.Resolve<IProduct>(modelType); 7: productDetailsLabel.Text = customModel.WriteProductDetails(); 8: } Pretty straight forward right? The only thing to note here is that the values in the dropdownlist item need to match the name attribute of the type. Depending on what you select, you’ll get an instance of either the Product class or the Product2 class and the corresponding WriteProductDetails() method is called. Now you see, how either of these methods can be used to create mock objects your the test project. See the code here. I’ll continue to share more of Unity in the next blog.

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• Using Unity Application Block – from basics to generics

  - by nmarun

  I just wanted to have one place where I list all the six Unity blogs I’ve written. Part 1: The very basics – Begin using Unity (code here) Part 2: Registering other types and resolving them (code here) Part 3: Lifetime Management (code here) Part 4: Constructor and Property or Setter Injection (code here) Part 5: Arrays (code here) Part 6: Generics (code here) Hope this helps someone (and this is the smallest blog I’ve posted till now).

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• ASP.NET Server-side comments

  - by nmarun

  I believe a good number of you know about Server-side commenting. This blog is just like a revival to refresh your memories. When you write comments in your .aspx/.ascx files, people usually write them as: 1: <!-- This is a comment. --> To show that it actually makes a difference for using the server-side commenting technique, I’ve started a web application project and my default.aspx page looks like this: 1: <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="ServerSideComment._Default" %> 2: <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> 3: </asp:Content> 4: <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> 5: <h2> 6: <!-- This is a comment --> 7: Welcome to ASP.NET! 8: </h2> 9: <p> 10: To learn more about ASP.NET visit <a href="http://www.asp.net" title="ASP.NET Website">www.asp.net</a>. 11: </p> 12: <p> 13: You can also find <a href="http://go.microsoft.com/fwlink/?LinkID=152368&amp;clcid=0x409" 14: title="MSDN ASP.NET Docs">documentation on ASP.NET at MSDN</a>. 15: </p> 16: </asp:Content> See the comment in line 6 and when I run the app, I can do a view source on the browser which shows up as: 1: <h2> 2: <!-- This is a comment --> 3: Welcome to ASP.NET! 4: </h2> Using Fiddler shows the page size as: Let’s change the comment style and use server-side commenting technique. 1: <h2> 2: <%-- This is a comment --%> 3: Welcome to ASP.NET! 4: </h2> Upon rendering, the view source looks like: 1: <h2> 2: 3: Welcome to ASP.NET! 4: </h2> Fiddler now shows the page size as: The difference is that client-side comments are ignored by the browser, but they are still sent down the pipe. With server-side comments, the compiler ignores everything inside this block. Visual Studio’s Text Editor toolbar also puts comments as server-side ones. If you want to give it a shot, go to your design page and press Ctrl+K, Ctrl+C on some selected text and you’ll see it commented in the server-side commenting style.

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• Using Unity – Part 6

  - by nmarun

  This is the last of the ‘Unity’ series and I’ll be talking about generics here. If you’ve been following the previous articles, you must have noticed that I’m just adding more and more ‘Product’ classes to the project. I’ll change that trend in this blog where I’ll be adding an ICaller interface and a Caller class. 1: public interface ICaller<T> where T : IProduct 2: { 3: string CallMethod<T>(string typeName); 4: } 5:  6: public class Caller<T> : ICaller<T> where T:IProduct 7: { 8: public string CallMethod<T>(string typeName) 9: { 10: //... 11: } 12: } We’ll fill-in the implementation of the CallMethod in a few, but first, here’s what we’re going to do: create an instance of the Caller class pass it the IProduct as a generic parameter in the CallMethod method, we’ll use Unity to dynamically create an instance of IProduct implemented object I need to add the config information for ICaller and Caller types. 1: <typeAlias alias="ICaller`1" type="ProductModel.ICaller`1, ProductModel" /> 2: <typeAlias alias="Caller`1" type="ProductModel.Caller`1, ProductModel" /> The .NET Framework’s convention to express generic types is ICaller`1, where the digit following the "`" matches the number of types contained in the generic type. So a generic type that contains 4 types contained in the generic type would be declared as: 1: <typeAlias alias="Caller`4" type="ProductModel.Caller`4, ProductModel" /> On my .aspx page, I have the following UI design: 1: <asp:RadioButton ID="LegacyProduct" Text="Product" runat="server" GroupName="ProductWeb" 2: AutoPostBack="true" OnCheckedChanged="RadioButton_CheckedChanged" /> 3: <br /> 4: <asp:RadioButton ID="NewProduct" Text="Product 2" runat="server" GroupName="ProductWeb" 5: AutoPostBack="true" OnCheckedChanged="RadioButton_CheckedChanged" /> 6: <br /> 7: <asp:RadioButton ID="ComplexProduct" Text="Product 3" runat="server" GroupName="ProductWeb" 8: AutoPostBack="true" OnCheckedChanged="RadioButton_CheckedChanged" /> 9: <br /> 10: <asp:RadioButton ID="ArrayConstructor" Text="Product 4" runat="server" GroupName="ProductWeb" 11: AutoPostBack="true" OnCheckedChanged="RadioButton_CheckedChanged" /> Things to note here are that all these radio buttons belong to the same GroupName => only one of these four can be clicked. Next, all four controls postback to the same ‘OnCheckedChanged’ event and lastly the ID’s point to named types of IProduct (already added to the web.config file). 1: <type type="IProduct" mapTo="Product" name="LegacyProduct" /> 2:  3: <type type="IProduct" mapTo="Product2" name="NewProduct" /> 4:  5: <type type="IProduct" mapTo="Product3" name="ComplexProduct"> 6: ... 7: </type> 8:  9: <type type="IProduct" mapTo="Product4" name="ArrayConstructor"> 10: ... 11: </type> In my calling code, I see which radio button was clicked, pass that as an argument to the CallMethod method. 1: protected void RadioButton_CheckedChanged(object sender, EventArgs e) 2: { 3: string typeName = ((RadioButton)sender).ID; 4: ICaller<IProduct> caller = unityContainer.Resolve<ICaller<IProduct>>(); 5: productDetailsLabel.Text = caller.CallMethod<IProduct>(typeName); 6: } What’s basically happening here is that the ID of the control gets passed on to the typeName which will be one of “LegacyProduct”, “NewProduct”, “ComplexProduct” or “ArrayConstructor”. I then create an instance of an ICaller and pass the typeName to it. Now, we’ll fill in the blank for the CallMethod method (sorry for the naming guys). 1: public string CallMethod<T>(string typeName) 2: { 3: IUnityContainer unityContainer = HttpContext.Current.Application["UnityContainer"] as IUnityContainer; 4: T productInstance = unityContainer.Resolve<T>(typeName); 5: return ((IProduct)productInstance).WriteProductDetails(); 6: } This is where I’ll resolve the IProduct by passing the type name and calling the WriteProductDetails() method. With all things in place, when I run the application and choose different radio buttons, the output should look something like below:          Basically this is how generics come to play in Unity. Please see the code I’ve used for this here. This marks the end of the ‘Unity’ series. I’ll definitely post any updates that I find, but for now I don’t have anything planned.

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• To ref or not to ref

  - by nmarun

  So the question is what is the point of passing a reference type along with the ref keyword? I have an Employee class as below: 1: public class Employee 2: { 3: public string FirstName { get; set; } 4: public string LastName { get; set; } 5:  6: public override string ToString() 7: { 8: return string.Format("{0}-{1}", FirstName, LastName); 9: } 10: } In my calling class, I say: 1: class Program 2: { 3: static void Main() 4: { 5: Employee employee = new Employee 6: { 7: FirstName = "John", 8: LastName = "Doe" 9: }; 10: Console.WriteLine(employee); 11: CallSomeMethod(employee); 12: Console.WriteLine(employee); 13: } 14:  15: private static void CallSomeMethod(Employee employee) 16: { 17: employee.FirstName = "Smith"; 18: employee.LastName = "Doe"; 19: } 20: }   After having a look at the code, you’ll probably say, Well, an instance of a class gets passed as a reference, so any changes to the instance inside the CallSomeMethod, actually modifies the original object. Hence the output will be ‘John-Doe’ on the first call and ‘Smith-Doe’ on the second. And you’re right: So the question is what’s the use of passing this Employee parameter as a ref? 1: class Program 2: { 3: static void Main() 4: { 5: Employee employee = new Employee 6: { 7: FirstName = "John", 8: LastName = "Doe" 9: }; 10: Console.WriteLine(employee); 11: CallSomeMethod(ref employee); 12: Console.WriteLine(employee); 13: } 14:  15: private static void CallSomeMethod(ref Employee employee) 16: { 17: employee.FirstName = "Smith"; 18: employee.LastName = "Doe"; 19: } 20: } The output is still the same: Ok, so is there really a need to pass a reference type using the ref keyword? I’ll remove the ‘ref’ keyword and make one more change to the CallSomeMethod method. 1: class Program 2: { 3: static void Main() 4: { 5: Employee employee = new Employee 6: { 7: FirstName = "John", 8: LastName = "Doe" 9: }; 10: Console.WriteLine(employee); 11: CallSomeMethod(employee); 12: Console.WriteLine(employee); 13: } 14:  15: private static void CallSomeMethod(Employee employee) 16: { 17: employee = new Employee 18: { 19: FirstName = "Smith", 20: LastName = "John" 21: }; 22: } 23: } In line 17 you’ll see I’ve ‘new’d up the incoming Employee parameter and then set its properties to new values. The output tells me that the original instance of the Employee class does not change. Huh? But an instance of a class gets passed by reference, so why did the values not change on the original instance or how do I keep the two instances in-sync all the times? Aah, now here’s the answer. In order to keep the objects in sync, you pass them using the ‘ref’ keyword. 1: class Program 2: { 3: static void Main() 4: { 5: Employee employee = new Employee 6: { 7: FirstName = "John", 8: LastName = "Doe" 9: }; 10: Console.WriteLine(employee); 11: CallSomeMethod(ref employee); 12: Console.WriteLine(employee); 13: } 14:  15: private static void CallSomeMethod(ref Employee employee) 16: { 17: employee = new Employee 18: { 19: FirstName = "Smith", 20: LastName = "John" 21: }; 22: } 23: } Viola! Now, to prove it beyond doubt, I said, let me try with another reference type: string. 1: class Program 2: { 3: static void Main() 4: { 5: string name = "abc"; 6: Console.WriteLine(name); 7: CallSomeMethod(ref name); 8: Console.WriteLine(name); 9: } 10:  11: private static void CallSomeMethod(ref string name) 12: { 13: name = "def"; 14: } 15: } The output was as expected, first ‘abc’ and then ‘def’ - proves the 'ref' keyword works here as well. Now, what if I remove the ‘ref’ keyword? The output should still be the same as the above right, since string is a reference type? 1: class Program 2: { 3: static void Main() 4: { 5: string name = "abc"; 6: Console.WriteLine(name); 7: CallSomeMethod(name); 8: Console.WriteLine(name); 9: } 10:  11: private static void CallSomeMethod(string name) 12: { 13: name = "def"; 14: } 15: } Wrong, the output shows ‘abc’ printed twice. Wait a minute… now how could this be? This is because string is an immutable type. This means that any time you modify an instance of string, new memory address is allocated to the instance. The effect is similar to ‘new’ing up the Employee instance inside the CallSomeMethod in the absence of the ‘ref’ keyword. Verdict: ref key came to the rescue and saved the planet… again!

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• WCF – interchangeable data-contract types

  - by nmarun

  In a WSDL based environment, unlike a CLR-world, we pass around the ‘state’ of an object and not the reference of an object. Well firstly, what does ‘state’ mean and does this also mean that we can send a struct where a class is expected (or vice-versa) as long as their ‘state’ is one and the same? Let’s see. So I have an operation contract defined as below: 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract] 5: Employee SaveEmployee(Employee employee); 6: } 7:  8: [ServiceBehavior] 9: public class LearnWcfService : ILearnWcfServiceExtend 10: { 11: public Employee SaveEmployee(Employee employee) 12: { 13: employee.EmployeeId = 123; 14: return employee; 15: } 16: } Quite simplistic operation there (which translates to ‘absolutely no business value’). Now, the data contract Employee mentioned above is a struct. 1: public struct Employee 2: { 3: public int EmployeeId { get; set; } 4:  5: public string FName { get; set; } 6: } After compilation and consumption of this service, my proxy (in the Reference.cs file) looks like below (I’ve ignored the rest of the details just to avoid unwanted confusion): 1: public partial struct Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged I call the service with the code below: 1: private static void CallWcfService() 2: { 3: Employee employee = new Employee { FName = "A" }; 4: Console.WriteLine("IsValueType: {0}", employee.GetType().IsValueType); 5: Console.WriteLine("IsClass: {0}", employee.GetType().IsClass); 6: Console.WriteLine("Before calling the service: {0} - {1}", employee.EmployeeId, employee.FName); 7: employee = LearnWcfServiceClient.SaveEmployee(employee); 8: Console.WriteLine("Return from the service: {0} - {1}", employee.EmployeeId, employee.FName); 9: } The output is: I now change my Employee type from a struct to a class in the proxy class and run the application: 1: public partial class Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged { The output this time is: The state of an object implies towards its composition, the properties and the values of these properties and not based on whether it is a reference type (class) or a value type (struct). And as shown above, we’re actually passing an object by its state and not by reference. Continuing on the same topic of ‘type-interchangeability’, WCF treats two data contracts as equivalent if they have the same ‘wire-representation’. We can do so using the DataContract and DataMember attributes’ Name property. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: public int Id { get; set; } 6:  7: [DataMember] 8: public string FirstName { get; set; } 9: } 10:  11: [DataContract(Name="Person")] 12: public class Employee 13: { 14: [DataMember(Name = "Id")] 15: public int EmployeeId { get; set; } 16:  17: [DataMember(Name="FirstName")] 18: public string FName { get; set; } 19: } I’ve created two data contracts with the exact same wire-representation. Just remember that the names and the types of data members need to match to be considered equivalent. The question then arises as to what gets generated in the proxy class. Despite us declaring two data contracts (Person and Employee), only one gets emitted – Person. This is because we’re saying that the Employee type has the same wire-representation as the Person type. Also that the signature of the SaveEmployee operation gets changed on the proxy side: 1: [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")] 2: [System.ServiceModel.ServiceContractAttribute(ConfigurationName="ServiceProxy.ILearnWcfServiceExtend")] 3: public interface ILearnWcfServiceExtend 4: { 5: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployee", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployeeResponse")] 6: ClientApplication.ServiceProxy.Person SaveEmployee(ClientApplication.ServiceProxy.Person employee); 7: } But, on the service side, the SaveEmployee still accepts and returns an Employee data contract. 1: [ServiceBehavior] 2: public class LearnWcfService : ILearnWcfServiceExtend 3: { 4: public Employee SaveEmployee(Employee employee) 5: { 6: employee.EmployeeId = 123; 7: return employee; 8: } 9: } Despite all these changes, our output remains the same as the last one: This is type-interchangeability at work! Here’s one more thing to ponder about. Our Person type is a struct and Employee type is a class. Then how is it that the Person type got emitted as a ‘class’ in the proxy? It’s worth mentioning that WSDL describes a type called Employee and does not say whether it is a class or a struct (see the SOAP message below): 1: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 2: xmlns:tem="http://tempuri.org/" 3: xmlns:ser="http://schemas.datacontract.org/2004/07/ServiceApplication"> 4: <soapenv:Header/> 5: <soapenv:Body> 6: <tem:SaveEmployee> 7: <!--Optional:--> 8: <tem:employee> 9: <!--Optional:--> 10: <ser:EmployeeId>?</ser:EmployeeId> 11: <!--Optional:--> 12: <ser:FName>?</ser:FName> 13: </tem:employee> 14: </tem:SaveEmployee> 15: </soapenv:Body> 16: </soapenv:Envelope> There are some differences between how ‘Add Service Reference’ and the svcutil.exe generate the proxy class, but turns out both do some kind of reflection and determine the type of the data contract and emit the code accordingly. So since the Employee type is a class, the proxy ‘Person’ type gets generated as a class. In fact, reflecting on svcutil.exe application, you’ll see that there are a couple of places wherein a flag actually determines a type as a class or a struct. One example is in the ExportISerializableDataContract method in the System.Runtime.Serialization.CodeExporter class. Seems like these flags have a say in deciding whether the type gets emitted as a struct or a class. This behavior is different if you use the WSDL tool though. WSDL tool does not do any kind of reflection of the data contract / serialized type, it emits the type as a class by default. You can check this using the two command lines below:   Note to self: Remember ‘state’ and type-interchangeability when traversing through the WSDL planet!

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• ASP.NET MVC 2 Model Binding for a Collection

  - by nmarun

  Yes, my yet another post on Model Binding (previous one is here), but this one uses features presented in MVC 2. How I got to writing this blog? Well, I’m on a project where we’re doing some MVC things for a shopping cart. Let me show you what I was working with. Below are my model classes: 1: public class Product 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: public int Quantity { get; set; } 6: public decimal UnitPrice { get; set; } 7: } 8:   9: public class Totals 10: { 11: public decimal SubTotal { get; set; } 12: public decimal Tax { get; set; } 13: public decimal Total { get; set; } 14: } 15:   16: public class Basket 17: { 18: public List<Product> Products { get; set; } 19: public Totals Totals { get; set;} 20: } The view looks as below:  1: <h2>Shopping Cart</h2> 2:   3: <% using(Html.BeginForm()) { %> 4: 5: <h3>Products</h3> 6: <% for (int i = 0; i < Model.Products.Count; i++) 7: { %> 8: <div style="width: 100px;float:left;">Id</div> 9: <div style="width: 100px;float:left;"> 10: <%= Html.TextBox("ID", Model.Products[i].Id) %> 11: </div> 12: <div style="clear:both;"></div> 13: <div style="width: 100px;float:left;">Name</div> 14: <div style="width: 100px;float:left;"> 15: <%= Html.TextBox("Name", Model.Products[i].Name) %> 16: </div> 17: <div style="clear:both;"></div> 18: <div style="width: 100px;float:left;">Quantity</div> 19: <div style="width: 100px;float:left;"> 20: <%= Html.TextBox("Quantity", Model.Products[i].Quantity)%> 21: </div> 22: <div style="clear:both;"></div> 23: <div style="width: 100px;float:left;">Unit Price</div> 24: <div style="width: 100px;float:left;"> 25: <%= Html.TextBox("UnitPrice", Model.Products[i].UnitPrice)%> 26: </div> 27: <div style="clear:both;"><hr /></div> 28: <% } %> 29: 30: <h3>Totals</h3> 31: <div style="width: 100px;float:left;">Sub Total</div> 32: <div style="width: 100px;float:left;"> 33: <%= Html.TextBox("SubTotal", Model.Totals.SubTotal)%> 34: </div> 35: <div style="clear:both;"></div> 36: <div style="width: 100px;float:left;">Tax</div> 37: <div style="width: 100px;float:left;"> 38: <%= Html.TextBox("Tax", Model.Totals.Tax)%> 39: </div> 40: <div style="clear:both;"></div> 41: <div style="width: 100px;float:left;">Total</div> 42: <div style="width: 100px;float:left;"> 43: <%= Html.TextBox("Total", Model.Totals.Total)%> 44: </div> 45: <div style="clear:both;"></div> 46: <p /> 47: <input type="submit" name="Submit" value="Submit" /> 48: <% } %> .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; } .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; } Nothing fancy, just a bunch of div’s containing textboxes and a submit button. Just make note that the textboxes have the same name as the property they are going to display. Yea, yea, I know. I’m displaying unit price as a textbox instead of a label, but that’s beside the point (and trust me, this will not be how it’ll look on the production site!!). The way my controller works is that initially two dummy products are added to the basked object and the Totals are calculated based on what products were added in what quantities and their respective unit price. So when the page loads in edit mode, where the user can change the quantity and hit the submit button. In the ‘post’ version of the action method, the Totals get recalculated and the new total will be displayed on the screen. Here’s the code: 1: public ActionResult Index() 2: { 3: Product product1 = new Product 4: { 5: Id = 1, 6: Name = "Product 1", 7: Quantity = 2, 8: UnitPrice = 200m 9: }; 10:   11: Product product2 = new Product 12: { 13: Id = 2, 14: Name = "Product 2", 15: Quantity = 1, 16: UnitPrice = 150m 17: }; 18:   19: List<Product> products = new List<Product> { product1, product2 }; 20:   21: Basket basket = new Basket 22: { 23: Products = products, 24: Totals = ComputeTotals(products) 25: }; 26: return View(basket); 27: } 28:   29: [HttpPost] 30: public ActionResult Index(Basket basket) 31: { 32: basket.Totals = ComputeTotals(basket.Products); 33: return View(basket); 34: } .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; } That’s that. Now I run the app, I see two products with the totals section below them. I look at the view source and I see that the input controls have the right ID, the right name and the right value as well. 1: <input id="ID" name="ID" type="text" value="1" /> 2: <input id="Name" name="Name" type="text" value="Product 1" /> 3: ... 4: <input id="ID" name="ID" type="text" value="2" /> 5: <input id="Name" name="Name" type="text" value="Product 2" /> .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; } So just as a regular user would do, I change the quantity value of one of the products and hit the submit button. The ‘post’ version of the Index method gets called and I had put a break-point on line 32 in the above snippet. When I hovered my mouse on the ‘basked’ object, happily assuming that the object would be all bound and ready for use, I was surprised to see both basket.Products and basket.Totals were null. Huh? A little research and I found out that the reason the DefaultModelBinder could not do its job is because of a naming mismatch on the input controls. What I mean is that when you have to bind to a custom .net type, you need more than just the property name. You need to pass a qualified name to the name property of the input control. I modified my view and the emitted code looked as below: 1: <input id="Product_Name" name="Product.Name" type="text" value="Product 1" /> 2: ... 3: <input id="Product_Name" name="Product.Name" type="text" value="Product 2" /> 4: ... 5: <input id="Totals_SubTotal" name="Totals.SubTotal" type="text" value="550" /> .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, I update the quantity and hit the submit button and I see that the Totals object is populated, but the Products list is still null. Once again I went: ‘Hmm.. time for more research’. I found out that the way to do this is to provide the name as: 1: <%= Html.TextBox(string.Format("Products[{0}].ID", i), Model.Products[i].Id) %> 2: <!-- this will be rendered as --> 3: <input id="Products_0__ID" name="Products[0].ID" type="text" value="1" /> .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; } It was only now that I was able to see both the products and the totals being properly bound in the ‘post’ action method. Somehow, I feel this is kinda ‘clunky’ way of doing things. Seems like people at MS felt in a similar way and offered us a much cleaner way to solve this issue. The simple solution is that instead of using a Textbox, we can either use a TextboxFor or an EditorFor helper method. This one directly spits out the name of the input property as ‘Products[0].ID and so on. Cool right? I totally fell for this and changed my UI to contain EditorFor helper method. At this point, I ran the application, changed the quantity field and pressed the submit button. Of course my basket object parameter in my action method was correctly bound after these changes. I let the app complete the rest of the lines in the action method. When the page finally rendered, I did see that the quantity was changed to what I entered before the post. But, wait a minute, the totals section did not reflect the changes and showed the old values. My status: COMPLETELY PUZZLED! Just to recap, this is what my ‘post’ Index method looked like: 1: [HttpPost] 2: public ActionResult Index(Basket basket) 3: { 4: basket.Totals = ComputeTotals(basket.Products); 5: return View(basket); 6: } .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; } A careful debug confirmed that the basked.Products[0].Quantity showed the updated value and the ComputeTotals() method also returns the correct totals. But still when I passed this basket object, it ended up showing the old totals values only. I began playing a bit with the code and my first guess was that the input controls got their values from the ModelState object. For those who don’t know, the ModelState is a temporary storage area that ASP.NET MVC uses to retain incoming attempted values plus binding and validation errors. Also, the fact that input controls populate the values using data taken from: Previously attempted values recorded in the ModelState["name"].Value.AttemptedValue Explicitly provided value (<%= Html.TextBox("name", "Some value") %>) ViewData, by calling ViewData.Eval("name") FYI: ViewData dictionary takes precedence over ViewData's Model properties – read more here. These two indicators led to my guess. It took me quite some time, but finally I hit this post where Brad brilliantly explains why this is the preferred behavior. My guess was right and I, accordingly modified my code to reflect the following way: 1: [HttpPost] 2: public ActionResult Index(Basket basket) 3: { 4: // read the following posts to see why the ModelState 5: // needs to be cleared before passing it the view 6: // http://forums.asp.net/t/1535846.aspx 7: // http://forums.asp.net/p/1527149/3687407.aspx 8: if (ModelState.IsValid) 9: { 10: ModelState.Clear(); 11: } 12:   13: basket.Totals = ComputeTotals(basket.Products); 14: return View(basket); 15: } .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; } What this does is that in the case where your ModelState IS valid, it clears the dictionary. This enables the values to be read from the model directly and not from the ModelState. So the verdict is this: If you need to pass other parameters (like html attributes and the like) to your input control, use 1: <%= Html.TextBox(string.Format("Products[{0}].ID", i), Model.Products[i].Id) %> .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; } Since, in EditorFor, there is no direct and simple way of passing this information to the input control. If you don’t have to pass any such ‘extra’ piece of information to the control, then go the EditorFor way. The code used in the post can be found here.

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• MVC 2 jQuery Client-side Validation

  - by nmarun

  Well, I watched Phil Haack’s show What's New in Microsoft ASP.NET MVC 2 and was impressed about the client-side validation (starts at 17:45) that MVC 2 offers. I tried creating the same, but Phil does not show what .js files need to be included and also I was not able to find the source code for the application that he used. In order to find out the required JavaScript file references, I added all of the files in my application to the page and ran it. Of course it worked, but this is definitely not an optimum solution. By removing one at a time and testing the app, I’ve short-listed the following ones: 1: <script src="../../Scripts/jquery-1.4.1.min.js" type="text/javascript"></script 2: <script src="../../Scripts/MicrosoftAjax.js" type="text/javascript"></script> 3: <script src="../../Scripts/MicrosoftMvcValidation.js" type="text/javascript"></script> Now, a little about the feature itself. Say, I’m working with a Book application so my model will look something like: 1: public class Book 2: { 3: [HiddenInput(DisplayValue = false)] 4: public int BookId { get; set; } 5:  6: [DisplayName("Book Title")] 7: [Required(ErrorMessage = "Book title is required")] 8: [StringLength(20, ErrorMessage = "Must be under 20 characters")] 9: public string Title { get; set; } 10:  11: [Required(ErrorMessage = "Author is required")] 12: [StringLength(40, ErrorMessage = "Must be under 40 characters")] 13: public string Author { get; set; } 14:  15: public decimal Price { get; set; } 16: 17: [DisplayName("ISBN")] 18: [StringLength(13, ErrorMessage = "Must be 13 characters")] 19: public string Isbn { get; set; } 20: } This ensures that the data passed will be validated upon post. But what would happen if you add the line (along with the above mentioned .js files): 1: <% Html.EnableClientValidation(); %> Now, this acts as ‘on-the-fly’ or ‘real-time’ validation. Now, when the user types 20 characters for the Title, the error shows up right on the 21st character. Beautiful… and you do not have to create the JavaScript function(s) for this. They’re auto-magically created for you. (Doing a ‘View Source’ on the browser page shows you the JavaScript logic that goes on behind the scenes). I bumped into another post that shows how .net 4 allows us to create custom validation attributes: Dynamic Range validation in MVC 2. This will help us attach virtually any business logic to the model itself. Please see the source code I’ve worked with.

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• readonly keyword

  - by nmarun

  This is something new that I learned about the readonly keyword. Have a look at the following class: 1: public class MyClass 2: { 3: public string Name { get; set; } 4: public int Age { get; set; } 5:  6: private readonly double Delta; 7:  8: public MyClass() 9: { 10: Initializer(); 11: } 12:  13: public MyClass(string name = "", int age = 0) 14: { 15: Name = name; 16: Age = age; 17: Initializer(); 18: } 19:  20: private void Initializer() 21: { 22: Delta = 0.2; 23: } 24: } I have a couple of public properties and a private readonly member. There are two constructors – one that doesn’t take any parameters and the other takes two parameters to initialize the public properties. I’m also calling the Initializer method in both constructors to initialize the readonly member. Now when I build this, the code breaks and the Error window says: “A readonly field cannot be assigned to (except in a constructor or a variable initializer)” Two things after I read this message: It’s such a negative statement. I’d prefer something like: “A readonly field can be assigned to (or initialized) only in a constructor or through a variable initializer” But in my defense, I AM assigning it in a constructor (only indirectly). All I’m doing is creating a method that does it and calling it in a constructor. Turns out, .net was not ‘frameworked’ this way. We need to have the member initialized directly in the constructor. If you have multiple constructors, you can just use the ‘this’ keyword on all except the default constructors to call the default constructor. This default constructor can then initialize your readonly members. This will ensure you’re not repeating the code in multiple places. A snippet of what I’m talking can be seen below: 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha; 10: private readonly int Beta; 11: private readonly double Delta; 12: private readonly double Gamma; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: } 26: } See the syntax in line 22 and you’ll know what I’m talking about. So the default constructor gets called before the one in line 22. These are known as constructor initializers and they allow one constructor to call another. The other ‘myth’ I had about readonly members is that you can set it’s value only once. This was busted as well (I recall Adam and Jamie’s show). Say you’ve initialized the readonly member through a variable initializer. You can over-write this value in any of the constructors any number of times. 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha = "asdf"; 10: private readonly int Beta = 15; 11: private readonly double Delta = 0.077; 12: private readonly double Gamma = 1.0; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: Beta = 3; 26: } 27:  28: public Person(string name, DateTime dob) : this() 29: { 30: Name = name; 31: DateOfBirth = dob; 32:  33: Alpha = ";LKJ"; 34: Gamma = 0.0898; 35: } 36:  37: public Person(int uniqueNumber, string name, int age, DateTime dob, string invoiceNumber) : this() 38: { 39: UniqueNumber = uniqueNumber; 40: Name = name; 41: Age = age; 42: DateOfBirth = dob; 43: InvoiceNumber = invoiceNumber; 44:  45: Alpha = "QWER"; 46: Beta = 5; 47: Delta = 1.0; 48: Gamma = 0.0; 49: } 50: } In the above example, every constructor over-writes the values for the readonly members. This is perfectly valid. There is a possibility that based on the way the object is instantiated, the readonly member will have a different value. Well, that’s all I have for today and read this as it’s on a related topic.

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• Windows 8 UX Guidelines in one PDF

  - by nmarun

  There are quite a few things you need do to differently in order to write a great Windows 8 App. Although MSDN has it documented completely in their site , the sheer volume of other related information might overwhelm you. In order to make it easy, they have a single pdf with all the relevant information. The file will also serve as a ‘quick ref’ document whether you are developing using C#-XAML or HTML5-JS-CSS or C++-DirectX style. And yes, this has been updated for the RTM version....(read more)

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• Parallel LINQ - PLINQ

  - by nmarun

  Turns out now with .net 4.0 we can run a query like a multi-threaded application. Say you want to query a collection of objects and return only those that meet certain conditions. Until now, we basically had one ‘control’ that iterated over all the objects in the collection, checked the condition on each object and returned if it passed. We obviously agree that if we can ‘break’ this task into smaller ones, assign each task to a different ‘control’ and ask all the controls to do their job - in-parallel, the time taken the finish the entire task will be much lower. Welcome to PLINQ. Let’s take some examples. I have the following method that uses our good ol’ LINQ. 1: private static void Linq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers =   from num in source 12: where IsDivisibleBy(num, 2) 13: select num; 14: 15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } I’ve added comments for the major steps, but the only thing I want to talk about here is the IsDivisibleBy() method. I know I could have just included the logic directly in the where clause. I called a method to add ‘delay’ to the execution of the query - to simulate a loooooooooong operation (will be easier to compare the results). 1: private static bool IsDivisibleBy(int number, int divisor) 2: { 3: // iterate over some database query 4: // to add time to the execution of this method; 5: // the TableB has around 10 records 6: for (int i = 0; i < 10; i++) 7: { 8: DataClasses1DataContext dataContext = new DataClasses1DataContext(); 9: var query = from b in dataContext.TableBs select b; 10: 11: foreach (var row in query) 12: { 13: // Do NOTHING (wish my job was like this) 14: } 15: } 16:  17: return number % divisor == 0; 18: } Now, let’s look at how to modify this to PLINQ. 1: private static void Plinq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers = from num in source.AsParallel() 12: where IsDivisibleBy(num, 2) 13: select num; 14:  15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } That’s it, this is now in PLINQ format. Oh and if you haven’t found the difference, look line 11 a little more closely. You’ll see an extension method ‘AsParallel()’ added to the ‘source’ variable. Couldn’t be more simpler right? So this is going to improve the performance for us. Let’s test it. So in my Main method of the Console application that I’m working on, I make a call to both. 1: static void Main(string[] args) 2: { 3: // set lower and upper limits 4: int lowerLimit = 1; 5: int upperLimit = 20; 6: // call the methods 7: Console.WriteLine("Calling Linq() method"); 8: Linq(lowerLimit, upperLimit); 9: 10: Console.WriteLine(); 11: Console.WriteLine("Calling Plinq() method"); 12: Plinq(lowerLimit, upperLimit); 13:  14: Console.ReadLine(); // just so I get enough time to read the output 15: } YMMV, but here are the results that I got:    It’s quite obvious from the above results that the Plinq() method is taking considerably less time than the Linq() version. I’m sure you’ve already noticed that the output of the Plinq() method is not in order. That’s because, each of the ‘control’s we sent to fetch the results, reported with values as and when they obtained them. This is something about parallel LINQ that one needs to remember – the collection cannot be guaranteed to be undisturbed. This could be counted as a negative about PLINQ (emphasize ‘could’). Nevertheless, if we want the collection to be sorted, we can use a SortedSet (.net 4.0) or build our own custom ‘sorter’. Either way we go, there’s a good chance we’ll end up with a better performance using PLINQ. And there’s another negative of PLINQ (depending on how you see it). This is regarding the CPU cycles. See the usage for Linq() method (used ResourceMonitor): I have dual CPU’s and see the height of the peak in the bottom two blocks and now compare to what happens when I run the Plinq() method. The difference is obvious. Higher usage, but for a shorter duration (width of the peak). Both these points make sense in both cases. Linq() runs for a longer time, but uses less resources whereas Plinq() runs for a shorter time and consumes more resources. Even after knowing all these, I’m still inclined towards PLINQ. PLINQ rocks! (no hard feelings LINQ)

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• ASP.NET MVC 2 throws exception for ‘favicon.ico’

  - by nmarun

  I must be on fire or something – third blog in 2 days… awesome! Before I begin, in case you’re wondering, favicon.ico is the small image that appears to the left of your web address, once the page loads. In order to learn more about MVC or any thing for that matter, it’s better to look at the source itself. Since MVC is open source (at least some part of it is), I started looking at the source code that’s available for download. While doing so, I hit Steve Sanderson’s blog site where he explains in great detail the way to debug your app using ASP.NET MVC source code. For those who are not aware, Steve Sanderson’s book - Pro ASP.NET MVC Framework, is one of the best books to learn about MVC. Alrighty, I followed the article and I hit F5 to debug the default / unchanged MVC project. I put a breakpoint in the DefaultControllerFactory.cs, CreateController() method. To know a little more about this class and the method, read this. Sure enough, the control stopped at the breakpoint and I hit F5 again and the page rendered just fine. But then what’s this? The breakpoint was hit again, as if something else was being requested. I now hovered my mouse over the ‘controllerName’ parameter and it says – favicon.ico. This by itself was more than enough for me to raise my eye-brows, but what happened next just took the ground below my feet. Oh, oh, I’m sorry I’m just typing, no code, no image, so here are a couple of screen captures. The first one shows the request for the Home controller; I get ‘Home’ when I hover over the parameter: And here’s the one that shows the same for call for ‘favicon.ico’. So, I step through the code and when the control reaches line 91 – GetControllerInstance() method, I step in. This is when I had the ‘ground-losing’ experience. Wow, an exception is being thrown for this file and that too in RTM. For some reason MVC thinks, this as a controller and tries to run it through the MvcHandler and it hits this snag. So it seems like this will happen for any MVC 2 site and this did not happen for me in the previous version of MVC. Before I get to how to resolve it, here’s another way of reproducing this exception. Revert back all your changes that you did as mentioned in Steve’s blog above. Now, add a class to your MVC project and call it say, MyControllerFactory and let this inherit from DefaultControllerFactory class. (Read this for details on the DefaultControllerFactory class is and how it is used in a different context). Add an override for the CreateController() method and for the sake of this blog, just copy the same content from the DefaultControllerFactory class. The last step is to tell your MVC app to use the MyControllerFactory class instead of the default one. To do this, go to your Global.asax.cs file and add line 6 of the snippet below: 1: protected void Application_Start() 2: { 3: AreaRegistration.RegisterAllAreas(); 4:   5: RegisterRoutes(RouteTable.Routes); 6: ControllerBuilder.Current.SetControllerFactory(new MyControllerFactory()); 7: } .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’re ready to reproduce the issue. Just F5 the project and when you hit the overridden CreateController() method for the second time, this is what it looks like for me: And continuing further gives me the same exception. I believe this is something that MS should fix, as not having ‘favicon.ico’ file will be common for most of the applications. So I think the when you create an MVC project, line 6 should be added by default by Visual Studio itself: 1: public class MvcApplication : System.Web.HttpApplication 2: { 3: public static void RegisterRoutes(RouteCollection routes) 4: { 5: routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); 6: routes.IgnoreRoute("favicon.ico"); 7:   8: routes.MapRoute( 9: "Default", // Route name 10: "{controller}/{action}/{id}", // URL with parameters 11: new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults 12: ); 13: } .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; } There it is, that’s the solution to avoid the exception altogether. I tried this both IE8 and Firefox browsers and was able to successfully reproduce the error. Hope someone will look at this issue and find a fix. Just before I finish up, I found another ‘bug’, if you want to call it, with Visual Studio 2008. Remember how you could change what browser you want your application to run in by just right clicking on the .aspx file and choosing ‘Browse with…’? Seems like that’s missing when you’re working with an MVC project. In order to test the above bug in the other browser, I had to load a classic ASP.NET project, change the settings and then run my MVC project. Felt kinda ‘icky’, for lack of a better word.

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• My app 'Howzzat Book–Windows 8 Metro App is in the store now

  - by nmarun

  I’m just so excited that my application Howzzat Book passed all certifications and is now in the Windows Store. Here’s the email from MIcrosoft that I received: “Your app is in the Windows Store! Congratulations! Howzzat Book, release 1 is now in the Windows Store. Use this link to your app’s listing in the Windows Store to let others know about your app.” Link for Howzzat Book Now, since they’ve just added it to the store, it might take some time to be available for download. So if you don’t find...(read more)

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• Get and Set property accessors are ‘actually’ methods

  - by nmarun

  Well, they are ‘special’ methods, but they indeed are methods. See the class below: 1: public class Person 2: { 3: private string _name; 4:  5: public string Name 6: { 7: get 8: { 9: return _name; 10: } 11: set 12: { 13: if (value == "aaa") 14: { 15: throw new ArgumentException("Invalid Name"); 16: } 17: _name = value; 18: } 19: } 20:  21: public void Save() 22: { 23: Console.WriteLine("Saving..."); 24: } 25: } Ok, so a class with a field, a property with the get and set accessors and a method. Now my calling code says: 1: static void Main() 2: { 3: try 4: { 5: Person person1 = new Person 6: { 7: Name = "aaa", 8: }; 9:  10: } 11: catch (Exception ex) 12: { 13: Console.WriteLine(ex.Message); 14: Console.WriteLine(ex.StackTrace); 15: Console.WriteLine("--------------------"); 16: } 17: } When the code is run, you’ll get the following exception message displayed: Now, you see the first line of the stack trace where it says that the exception was thrown in the method set_Name(String value). Wait a minute, we have not declared any method with that name in our Person class. Oh no, we actually have. When you create a property, this is what happens behind the screen. The CLR creates two methods for each get and set property accessor. Let’s look at the signature once again: set_Name(String value) This also tells you where the ‘value’ keyword comes from in our set property accessor. You’re actually wiring up a method parameter to a field. 1: set 2: { 3: if (value == "aaa") 4: { 5: throw new ArgumentException("Invalid Name"); 6: } 7: _name = value; 8: } Digging deeper on this, I ran the ILDasm tool and this is what I see: We see the ‘free’ constructor (named .ctor) that the compiler gives us, the _name field, the Name property and the Save method. We also see the get_Name and set_Name methods. In order to compare the Save and the set_Name methods, I double-clicked on the two methods and this is what I see: The ‘.method’ keyword tells that both Save and set_Name are both methods (no guessing there!). Seeing the set_Name method as a public method did kinda surprise me. So I said, why can’t I do a person1.set_Name(“abc”) since it is declared as public. This cannot be done because the get_Name and set_Name methods have an extra attribute called ‘specialname’. This attribute is used to identify an IL (Intermediate Language) token that can be treated with special care by the .net language. So the thumb-rule is that any method with the ‘specialname’ attribute cannot be generally called / invoked by the user (a simple test using intellisense proves this). Their functionality is exposed through other ways. In our case, this is done through the property itself. The same concept gets extended to constructors as well making them special methods too. These so-called ‘special’ methods can be identified through reflection. 1: static void ReflectOnPerson() 2: { 3: Type personType = typeof(Person); 4:  5: MethodInfo[] methods = personType.GetMethods(); 6:  7: for (int i = 0; i < methods.Length; i++) 8: { 9: Console.Write("Method: {0}", methods[i].Name); 10: // Determine whether or not each method is a special name. 11: if (methods[i].IsSpecialName) 12: { 13: Console.Write(" has 'SpecialName' attribute"); 14: } 15: Console.WriteLine(); 16: } 17: } Line 11 shows the ‘IsSpecialName’ boolean property. So a method with a ‘specialname’ attribute gets mapped to the IsSpecialName property. The output is displayed as: Wuhuuu! There they are.. our special guests / methods. Verdict: Getting to know the internals… helps!

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• WSDL-world vs CLR-world – some differences

  - by nmarun

  A change in mindset is required when switching between a typical CLR application and a web service application. There are some things in a CLR environment that just don’t add-up in a WSDL arena (and vice-versa). I’m listing some of them here. When I say WSDL-world, I’m mostly talking with respect to a WCF Service and / or a Web Service. No (direct) Method Overloading: You definitely can have overloaded methods in a, say, Console application, but when it comes to a WCF / Web Services application, you need to adorn these overloaded methods with a special attribute so the service knows which specific method to invoke. When you’re working with WCF, use the Name property of the OperationContract attribute to provide unique names. 1: [OperationContract(Name = "AddInt")] 2: int Add(int arg1, int arg2); 3:  4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); By default, the proxy generates the code for this as: 1: [System.ServiceModel.OperationContractAttribute( 2: Action="http://tempuri.org/ILearnWcfService/AddInt", 3: ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute( 7: Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", 8: ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 9: double AddDouble(double arg1, double arg2); With Web Services though the story is slightly different. Even after setting the MessageName property of the WebMethod attribute, the proxy does not change the name of the method, but only the underlying soap message changes. 1: [WebMethod] 2: public string HelloGalaxy() 3: { 4: return "Hello Milky Way!"; 5: } 6:  7: [WebMethod(MessageName = "HelloAnyGalaxy")] 8: public string HelloGalaxy(string galaxyName) 9: { 10: return string.Format("Hello {0}!", galaxyName); 11: } The one thing you need to remember is to set the WebServiceBinding accordingly. 1: [WebServiceBinding(ConformsTo = WsiProfiles.None)] The proxy is: 1: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloGalaxy", 2: RequestNamespace="http://tempuri.org/", 3: ResponseNamespace="http://tempuri.org/", 4: Use=System.Web.Services.Description.SoapBindingUse.Literal, 5: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 6: public string HelloGalaxy() 7:  8: [System.Web.Services.WebMethodAttribute(MessageName="HelloGalaxy1")] 9: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloAnyGalaxy", 10: RequestElementName="HelloAnyGalaxy", 11: RequestNamespace="http://tempuri.org/", 12: ResponseElementName="HelloAnyGalaxyResponse", 13: ResponseNamespace="http://tempuri.org/", 14: Use=System.Web.Services.Description.SoapBindingUse.Literal, 15: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 16: [return: System.Xml.Serialization.XmlElementAttribute("HelloAnyGalaxyResult")] 17: public string HelloGalaxy(string galaxyName) 18:  You see the calling method name is the same in the proxy, however the soap message that gets generated is different. Using interchangeable data types: See details on this here. Type visibility: In a CLR-based application, if you mark a field as private, well we all know, it’s ‘private’. Coming to a WSDL side of things, in a Web Service, private fields and web methods will not get generated in the proxy. In WCF however, all your operation contracts will be public as they get implemented from an interface. Even in case your ServiceContract interface is declared internal/private, you will see it as a public interface in the proxy. This is because type visibility is a CLR concept and has no bearing on WCF. Also if a private field has the [DataMember] attribute in a data contract, it will get emitted in the proxy class as a public property for the very same reason. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: private int _x; 6:  7: [DataMember] 8: public int Id { get; set; } 9:  10: [DataMember] 11: public string FirstName { get; set; } 12:  13: [DataMember] 14: public string Header { get; set; } 15: } 16: } See the ‘_x’ field is a private member with the [DataMember] attribute, but the proxy class shows as below: 1: [System.Runtime.Serialization.DataMemberAttribute()] 2: public int _x { 3: get { 4: return this._xField; 5: } 6: set { 7: if ((this._xField.Equals(value) != true)) { 8: this._xField = value; 9: this.RaisePropertyChanged("_x"); 10: } 11: } 12: } Passing derived types to web methods / operation contracts: Once again, in a CLR application, I can have a derived class be passed as a parameter where a base class is expected. I have the following set up for my WCF service. 1: [DataContract] 2: public class Employee 3: { 4: [DataMember(Name = "Id")] 5: public int EmployeeId { get; set; } 6:  7: [DataMember(Name="FirstName")] 8: public string FName { get; set; } 9:  10: [DataMember] 11: public string Header { get; set; } 12: } 13:  14: [DataContract] 15: public class Manager : Employee 16: { 17: [DataMember] 18: private int _x; 19: } 20:  21: // service contract 22: [OperationContract] 23: Manager SaveManager(Employee employee); 24:  25: // in my calling code 26: Manager manager = new Manager {_x = 1, FirstName = "abc"}; 27: manager = LearnWcfServiceClient.SaveManager(manager); The above will throw an exception saying: In short, this is saying, that a Manager type was found where an Employee type was expected! Hierarchy flattening of interfaces in WCF: See details on this here. In CLR world, you’ll see the entire hierarchy as is. That’s another difference. Using ref parameters: * can use ref for parameters, but operation contract should not be one-way (gives an error when you do an update service reference)   => bad programming; create a return object that is composed of everything you need! This one kind of stumped me. Not sure why I tried this, but you can pass parameters prefixed with ref keyword* (* terms and conditions apply). The main issue is this, how would we know the changes that were made to a ‘ref’ input parameter are returned back from the service and updated to the local variable? Turns out both Web Services and WCF make this tracking happen by passing the input parameter in the response soap. This way when the deserializer does its magic, it maps all the elements of the response xml thereby updating our local variable. Here’s what I’m talking about. 1: [WebMethod(MessageName = "HelloAnyGalaxy")] 2: public string HelloGalaxy(ref string galaxyName) 3: { 4: string output = string.Format("Hello {0}", galaxyName); 5: if (galaxyName == "Andromeda") 6: { 7: galaxyName = string.Format("{0} (2.5 million light-years away)", galaxyName); 8: } 9: return output; 10: } This is how the request and response look like in soapUI. As I said above, the behavior is quite similar for WCF as well. But the catch comes when you have a one-way web methods / operation contracts. If you have an operation contract whose return type is void, is marked one-way and that has ref parameters then you’ll get an error message when you try to reference such a service. 1: [OperationContract(Name = "Sum", IsOneWay = true)] 2: void Sum(ref double arg1, ref double arg2); 3:  4: public void Sum(ref double arg1, ref double arg2) 5: { 6: arg1 += arg2; 7: } This is what I got when I did an update to my service reference: Makes sense, because a OneWay operation is… one-way – there’s no returning from this operation. You can also have a one-way web method: 1: [SoapDocumentMethod(OneWay = true)] 2: [WebMethod(MessageName = "HelloAnyGalaxy")] 3: public void HelloGalaxy(ref string galaxyName) This will throw an exception message similar to the one above when you try to update your web service reference. In the CLR space, there’s no such concept of a ‘one-way’ street! Yes, there’s void, but you very well can have ref parameters returned through such a method. Just a point here; although the ref/out concept sounds cool, it’s generally is a code-smell. The better approach is to always return an object that is composed of everything you need returned from a method. These are some of the differences that we need to bear when dealing with services that are different from our daily ‘CLR’ life.

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• HTML5-MVC application using VS2010 SP1

  - by nmarun

  This is my first attempt at creating HTML5 pages. VS 2010 allows working with HTML5 now (you just need to make a small change after installing SP1). So my Razor view is now a HTML5 page. I call this application - 5Commerce – (an over-simplified) HTML5 ECommerce site. So here’s the flow of the application: home page renders user enters first and last name, chooses a product and the quantity can enter additional instructions for the order place the order user is then taken to another page showing the order details Off to the details. This is what my page looks in Google Chrome 10 beta (or later) soon after it renders. Here are some of the things to observe on this. Look a little closer and you’ll see a border around the first name textbox – this is ‘autofocus’ in action. I’ve set the autofocus attribute on this textbox. So as soon as the page loads, this control gets focus. 1: <input type="text" autofocus id="firstName" class="inputWidth" data_minlength="" 2: data_maxlength="" placeholder="first name" /> See a partially grayed out ‘last name’ text in the second textbox. This is set using a placeholder attribute (see above). It gets wiped out on-focus and improves the UI visuals in general. The quantity textbox is actually a numerical-only textbox. 1: <input type="number" id="quantity" data_mincount="" class="inputWidth" /> The last line is for additional instructions. This looks like a label but it’s content is editable. Just adding the ‘contenteditable’ attribute to the span allow the user to edit the text inside. 1: <span contenteditable id="additionalInstructions" data_texttype="" class="editableContent">select text and edit </span> All of the above is just plain HTML (no lurking javascript acting in here). Makes it real clean and simple. Going more into the HTML, I see that the _Layout.cshtml already is using some HTML5 content. I created my project before installing SP1, so that was the reason for my surprise. 1: <!DOCTYPE html> This is the doctype declaration in HTML5 and this is supported even by IE6 (just take my word on IE6 now, don’t go install it to test it, especially when MS is doing an IE6 countdown). That’s just amazing and extremely easy to read remember and talk about a few less bytes on every call! I modified the rest of my _Layout.cshtml to the below: 1: <!DOCTYPE html> 2: <html> 3: <head> 4: <title>5Commerce - HTML 5 Ecommerce site</title> 5: <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" /> 6: <script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script> 7: <script src="@Url.Content("~/Scripts/CustomScripts.js")" type="text/javascript"></script> 8: <script type="text/javascript"> 9: $(document).ready(function () { 10: WireupEvents(); 11: }); 12:</script> 13:  14: </head> 15:  16: <body role="document" class="bodybackground"> 17: <header role="heading"> 18: <h2>5Commerce - HTML 5 Ecommerce site!</h2> 19: </header> 20: <section id="mainForm"> 21: @RenderBody() 22: </section> 23: <footer id="page_footer" role="siteBaseInfo"> 24: <p>&copy; 2011 5Commerce Inc!</p> 25: </footer> 26: </body> 27: </html> I’m sure you’re seeing some of the new tags here. To give a brief intro about them: <header>, <footer>: Marks the header/footer region of a page or section. <section>: A logical grouping of content role attribute: Identifies the responsibility of an element. This attribute can be used by screen readers and can also be filtered through jQuery. SP1 also allows for some intellisense in HTML5. You see the other types of input fields – email, date, datetime, month, url and there are others as well. So once my page loads, i.e., ‘on document ready’, I’m wiring up the events following the principles of unobtrusive javascript. In the snippet below, I’m controlling the behavior of the input controls for specific events. 1: $("#productList").bind('change blur', function () { 2: IsSelectedProductValid(); 3: }); 4:  5: $("#quantity").bind('blur', function () { 6: IsQuantityValid(); 7: }); 8:  9: $("#placeOrderButton").click( 10: function () { 11: if (IsPageValid()) { 12: LoadProducts(); 13: } 14: }); This enables some client-side validation to occur before the data is sent to the server. These validation constraints are obtained through a JSON call to the WCF service and are set to the ‘data_’ attributes of the input controls. Have a look at the ‘GetValidators()’ function below: 1: function GetValidators() { 2: // the post to your webservice or page 3: $.ajax({ 4: type: "GET", //GET or POST or PUT or DELETE verb 5: url: "http://localhost:14805/OrderService.svc/GetValidators", // Location of the service 6: data: "{}", //Data sent to server 7: contentType: "application/json; charset=utf-8", // content type sent to server 8: dataType: "json", //Expected data format from server 9: processdata: true, //True or False 10: success: function (result) {//On Successfull service call 11: if (result.length > 0) { 12: for (i = 0; i < result.length; i++) { 13: if (result[i].PropertyName == "FirstName") { 14: if (result[i].MinLength > 0) { 15: $("#firstName").attr("data_minLength", result[i].MinLength); 16: } 17: if (result[i].MaxLength > 0) { 18: $("#firstName").attr("data_maxLength", result[i].MaxLength); 19: } 20: } 21: else if (result[i].PropertyName == "LastName") { 22: if (result[i].MinLength > 0) { 23: $("#lastName").attr("data_minLength", result[i].MinLength); 24: } 25: if (result[i].MaxLength > 0) { 26: $("#lastName").attr("data_maxLength", result[i].MaxLength); 27: } 28: } 29: else if (result[i].PropertyName == "Quantity") { 30: if (result[i].MinCount > 0) { 31: $("#quantity").attr("data_minCount", result[i].MinCount); 32: } 33: } 34: else if (result[i].PropertyName == "AdditionalInstructions") { 35: if (result[i].TextType.length > 0) { 36: $("#additionalInstructions").attr("data_textType", result[i].TextType); 37: } 38: } 39: } 40: } 41: }, 42: error: function (result) {// When Service call fails 43: alert('Service call failed: ' + result.status + ' ' + result.statusText); 44: } 45: }); 46:  47: //.... 48: } Just before the GetValidators() function runs and sets the validation constraints, this is what the html looks like (seen through the Dev tools of Chrome): After the function executes, you see the values in the ‘data_’  attributes. As and when we enter valid data into these fields, the error messages disappear, since the validation is bound to the blur event of the control. There you see… no error messages (well, the catch here is that once you enter THAT name, all errors disappear automatically). Clicking on ‘Place Order!’ runs the SaveOrder function. You can see the JSON for the order object that is getting constructed and passed to the WCF Service. 1: function SaveOrder() { 2: var addlInstructionsDefaultText = "select text and edit"; 3: var addlInstructions = $("span:first").text(); 4: if(addlInstructions == addlInstructionsDefaultText) 5: { 6: addlInstructions = ''; 7: } 8: var orderJson = { 9: AdditionalInstructions: addlInstructions, 10: Customer: { 11: FirstName: $("#firstName").val(), 12: LastName: $("#lastName").val() 13: }, 14: OrderedProduct: { 15: Id: $("#productList").val(), 16: Quantity: $("#quantity").val() 17: } 18: }; 19:  20: // the post to your webservice or page 21: $.ajax({ 22: type: "POST", //GET or POST or PUT or DELETE verb 23: url: "http://localhost:14805/OrderService.svc/SaveOrder", // Location of the service 24: data: JSON.stringify(orderJson), //Data sent to server 25: contentType: "application/json; charset=utf-8", // content type sent to server 26: dataType: "json", //Expected data format from server 27: processdata: false, //True or False 28: success: function (result) {//On Successfull service call 29: window.location.href = "http://localhost:14805/home/ShowOrderDetail/" + result; 30: }, 31: error: function (request, error) {// When Service call fails 32: alert('Service call failed: ' + request.status + ' ' + request.statusText); 33: } 34: }); 35: } The service saves this order into an XML file and returns the order id (a guid). On success, I redirect to the ShowOrderDetail action method passing the guid. This page will show all the details of the order. Although the back-end weightlifting is done by WCF, I did not show any of that plumbing-work as I wanted to concentrate more on the HTML5 and its associates. However, you can see it all in the source here. I do have one issue with HTML5 and this is an existing issue with HTML4 as well. If you see the snippet above where I’ve declared a textbox for first name, you’ll see the autofocus attribute just dangling by itself. It doesn’t follow the xml syntax of ‘key="value"’ allowing users to continue writing badly-formatted html even in the new version. You’ll see the same issue with the ‘contenteditable’ attribute as well. The work-around is that you can do ‘autofocus=”true”’ and it’ll work fine plus make it well-formatted. But unless the standards enforce this, there will be people (me included) who’ll get by, by just typing the bare minimum! Hoping this will get fixed in the coming version-updates. Source code here. Verdict: I think it’s time for us to embrace the new HTML5. Thank you HTML4 and Welcome HTML5.

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• Templated Razor Delegates – Phil Haack

  - by nmarun

  This post is largely based off of Phil Haack’s article titled Templated Razor Delegates. I strongly recommend reading this article first. Here’s a sample code for the same, so you can have a look at. I also have a custom type being rendered as a table. 1: // my custom type 2: public class Device 3: { 4: public int Id { get; set; } 5: public string Name { get; set; } 6: public DateTime MfgDate { get; set; } 7: } Now I can write an extension method just for this type. 1: public static class RazorExtensions 2: { 3: public static HelperResult List(this IList<Models.Device> devices, Func<Models.Device, HelperResult> template) 4: { 5: return new HelperResult(writer => 6: { 7: foreach (var device in devices) 8: { 9: template(device).WriteTo(writer); 10: } 11: }); 12: } 13: // ... 14: } Modified my view to make it a strongly typed one and included html to render my custom type collection in a table. 1: @using TemplatedRazorDelegates 2: @model System.Collections.Generic.IList<TemplatedRazorDelegates.Models.Device> 3:  4: @{ 5: ViewBag.Title = "Home Page"; 6: } 7:  8: <h2>@ViewBag.Message</h2> 9:  10: @{ 11: var items = new[] { "one", "two", "three" }; 12: IList<int> ints = new List<int> { 1, 2, 3 }; 13: } 14:  15: <ul> 16: @items.List(@<li>@item</li>) 17: </ul> 18: <ul> 19: @ints.List(@<li>@item</li>) 20: </ul> 21:  22: <table> 23: <tr><th>Id</th><th>Name</th><th>Mfg Date</th></tr> 24: @Model.List(@<tr><td>@item.Id</td><td>@item.Name</td><td>@item.MfgDate.ToShortDateString()</td></tr>) 25: </table> We get intellisense as well! Just added some items in the action method of the controller: 1: public ActionResult Index() 2: { 3: ViewBag.Message = "Welcome to ASP.NET MVC!"; 4: IList<Device> devices = new List<Device> 5: { 6: new Device {Id = 1, Name = "abc", MfgDate = new DateTime(2001, 10, 19)}, 7: new Device {Id = 2, Name = "def", MfgDate = new DateTime(2011, 1, 1)}, 8: new Device {Id = 3, Name = "ghi", MfgDate = new DateTime(2003, 3, 15)}, 9: new Device {Id = 4, Name = "jkl", MfgDate = new DateTime(2007, 6, 6)} 10: }; 11: return View(devices); 12: } Running this I get the output as: Absolutely brilliant! Thanks to both Phil Haack and to David Fowler for bringing this out to us. Download the code for this from here. Verdict: RazorViewEngine.Points += 1;

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• 8 tips for your Windows Store apps

  - by nmarun

  1. Use Basic page than a blank template For a good number of your tasks, you probably need a Basic page. For starters, this page gives you the bare-bones required – a ‘Go back’ button and a placeholder for the applcation name. This page also contains the VisualState for Snapped view, so you don’t have to handle it in code. When you choose to add a basic page to an empty solution, you’ll get a prompt like below. Clicking on yes, adds some of the following files: LayoutAwarePage – handles GoBack and...(read more)

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• Top 10 posts of 2010

  - by nmarun

  I quote one of my professors when I say: “We Share – We Improve”. It is through blogging that I’ve learned quite a bit. The ‘R&D’ done to learn and perfect a technology and the comments by other experts adds towards skill-set building. Below are some of the articles that I’m glad I blogged about. ASP.NET MVC 2 Model Binding for a Collection MVC 3 - first look To ref or not to ref Xap Reflector – Silverlight 4 Beware of const members LINQ to JS COM Automation with OpenOffice – Silverlight 4 VS 2010 Productivity Power Tools Using Unity Application Block – from basics to generics ASP.NET MVC Model Binding Wishing you all a happy 2011 and keep/start blogging!

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• Hierarchy flattening of interfaces in WCF

  - by nmarun

  Alright, so say I have my service contract interface as below: 1: [ServiceContract] 2: public interface ILearnWcfService 3: { 4: [OperationContract(Name = "AddInt")] 5: int Add(int arg1, int arg2); 6: } Say I decided to add another interface with a similar add “feature”. 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); 6: } My class implementing the ILearnWcfServiceExtend ends up as: 1: public class LearnWcfService : ILearnWcfServiceExtend 2: { 3: public int Add(int arg1, int arg2) 4: { 5: return arg1 + arg2; 6: } 7:  8: public double Add(double arg1, double arg2) 9: { 10: return arg1 + arg2; 11: } 12: } Now when I consume this service and look at the proxy that gets generated, here’s what I see: 1: public interface ILearnWcfServiceExtend 2: { 3: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfService/AddInt", ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 7: double AddDouble(double arg1, double arg2); 8: } Only the ILearnWcfServiceExtend gets ‘listed’ in the proxy class and not the (base interface) ILearnWcfService interface. But then to uniquely identify the operations that the service exposes, the Action and ReplyAction properties are set. So in the above example, the AddInt operation has the Action property set to ‘http://tempuri.org/ILearnWcfService/AddInt’ and the AddDouble operation has the Action property of ‘http://tempuri.org/ILearnWcfServiceExtend/AddDouble’. Similarly the ReplyAction properties are set corresponding to the namespace that they’re declared in. The ‘http://tempuri.org’ is chosen as the default namespace, since the Namespace property on the ServiceContract is not defined. The other thing is the service contract itself – the Add() method. You’ll see that in both interfaces, the method names are the same. As you might know, this is not allowed in WSDL-based environments, even though the arguments are of different types. This is allowed only if the Name attribute of the ServiceContract is set (as done above). This causes a change in the name of the service contract itself in the proxy class. See that their names are changed to AddInt / AddDouble respectively. Lesson learned: The interface hierarchy gets ‘flattened’ when the WCF service proxy class gets generated.

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