Nairooz Nilafdeen's Blog

Almost after .Net 4 was released I remember reading about MEF (Managed Extensibility Framework), this was a framework for developers to compose their application with required dependencies. At first this looks like the Unity Container used for dependency injection, but MEF is much more than a dependency container but there is nothing stopping you from using MEF as a dependency injector. I remember around 5 years back when I was in a project that created a framework that allows developers to plug-in there modules as WinForm screens. The developer would create a set of screens with the intended functionalities and the drop this component in the bin folder of the framework and then will move on to do some painful configurations for the framework to pick up the module. Dropping the component into the bin folder and doing a bit of configuration is all that s needed for the framework to pick up display the screens. Typically, the configurations would also contain metadata about the screen....

One of the key features in .Net 4.5 is to write asynchronous programs much easier. So if I was to write asynchronous programs in .Net 2.0/3.5, I would either follow the event based model or the callback based model. For an example, a synchronous method that does intensive work (say the DoWork()) can be made asynchronous by using the following patterns 1) Implementing the IAsyncResult pattern. in this implementation, 2 methods are exposed for the DoWork() synchronous method, the BeginDoWork() and the EndDoWork() method. The user will call the BeingDoWork() passing in the required parameters and a callback of the delegate type AsyncCallback(IAsyncResult). The BeginDoWork() will spawn a new thread a return control back to the user. Once work is completed in the spawned method, as a last step, it will call the inform the AsyncResult implementation, which in turns will call the EndDoWork() (which is the callback that was passed in to the BeginDoWork()). 2) Implementing the event pattern. ...

Sometimes back, ASP.NET MVC 4 beta was release, this comes with quite a lot of capabilities to create mobile web applications with HTML5, to new features on Razor etc.. One of the milestones of this release is ASP.NET Web APIs, which allows developers to implement REST services. .NET 3.5/4.0 WCF provides us with the support of creating REST APIs using the webHttpBinding, however most of the features required to run the service needs the ASP.NET compatibility mode, this basically means the request to the REST service would first go through the ASP.NET pipeline, before being handed over to WCF. Then there was the WCF Web API, where Microsoft tried to re-define how REST services are created, but they opted in for moving REST support into ASP.NET and then to WCF, hence ASP.NET Web API, becomes the de facto technology for creating REST services. WCF WebHttpBinding would still exist, bu the recommendation is to to use Web APIs. Implementing a Web API is simple, the steps involved are... 1) C...

Someone asked me the question whether a simple factory can be implemented using dependency injection container. The example he bought up is where a simple factory takes in a string and switches this string to return the correct instance of the object needed....I am talking about something like this. internal IWaterMarkProvider GetProvider( string fileExtension) { IWaterMarkProvider provider = null ; switch (fileExtension.ToLower()) { case "pdf" : provider = new PDFProvider (); break ; case ".docx" : provider = new WordProvider (); break ; case "pptx" : provider = new PPTProvider (); break ; case "xlsx" : provider = new ExcelProvider (); break ; } return provider; } The answer was yes..So, if you are using Microsoft Unity (a dependency injection container), you would have your configuration file like this... < configuration > < configSections ...

.Net 4.0 introduced the System.Runtime.Caching namespace, this made developers to make use of caching functionality independent of the cache found in the System.Web DLL. Caching using the System.Runtime.Caching provides an in memory cache but also allows developers to extend this with a different provider. For an example, you could have an implementation that could hold the items in memory but also persists it into the hard disk for the fear of cache eviction. Adding an item into the cache is done this way... //Get the default cache MemoryCache cache = MemoryCache .Default; //Add the item cache.Add( "MyKey" , "Nairooz Nilafdeen" , DateTimeOffset .Now.AddMinutes(19)); //Get the item from the cache if (cache.Contains( "MyKey" )) { Console .WriteLine(cache.Get( "MyKey" )); } The caching namespace also allows you to set ChangeMonitors for the cache policy, for an example, you can specify that the cache needs...

If you have used libraries like Json.Net or the DataContractSerializer or the JavaScriptSerializer, you already know that you would need a strong typed object for you to convert you class hiarachy into JSON. In a few cases this is frustrating. In one of my earlier posts I talked about DynamicJson, this was an open source library (under MS-PL license) for you to create JSON counterparts from dynamic objects. DynamicJson allows you to create JSON values from dynamic object, meaning you don’t really need to create a strong typed object, but create your JSON representation on the fly. >net 4.5 comes with a new namespace System.JSON, that exposes similar functionalities. You can try this out by installing System.Json from NuGet. It works seamlessly as .Net 4.5 is just a replacement for .NET 4.0. So using System.Json, I can create JSON string like this… dynamic book = new JsonObject (); book.BookName = "Asp.NET MVC" ; book.Price = 123.45; ...

As everyone knows JSON is a very light weight form of transport when it comes to the web, you can respond and consume JSON using WCF REST services, I have blogged about this in one of my earlier posts in 2008, but last month I got to work on this... WCF makes things very easy, if the client sends a JSON formatted string, WCF infrastructure will de-serialize this into a custom type that you have specified in your operation contract. For an example... [WebInvoke(Method="POST"....)] public void Save(Student student){} so if you send a JSON string like this on your POST body {Name : "Nairooz Nilafdeen", Age : 26} ...the WCF infrastructure will de-serialize the JSON string into the Student object (as long as the JSON key-value matches the properties in the Student type).. Now, the problem with this approach is when you send a JSON string that contains an additional property that is not available in the Student class, now WCF will not be able to de-serial...