RESTing with the Microsoft REST Starter Kit

June 22, 2009
By Jeffrey Juday

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HttpStage

One other interesting feature of the HttpClient is the HttpStage Collection. HttpStage collection acts as a sort of pipeline for the HttpClient allowing things like caching data or performing additional operations on the HttpRequestMesage or HttpResponseMessage. Below is the StageProcessingTest class implementation.

  class StageProcessingTest : HttpProcessingStage
  {
      public override void ProcessRequest(HttpRequestMessage request)
      {
          Console.WriteLine("Request stage executed...");
      }
  
      public override void ProcessResponse(HttpResponseMessage response)
      {
          SampleResponseBody respBody = null;
  
          response.Content.LoadIntoBuffer();
  
          respBody = response.Content.ReadAsDataContract<SAMPLERESPONSEBODY>();
  
          Console.WriteLine( "Response stage executed... " + respBody.Value + " added something");
          
      }
  }

HttpProcessingStage, the base class for StageProcessingTest, is a specialized implementation of HttpStage.

Async Programming Model

Below is the same Post performed above, but this time using the Asynchronous Programming Model.

      request.Data = "My request asnyc...";
      HttpContent content = HttpContentExtensions.CreateDataContract(request);
      Uri doWork = new Uri("DoWork", UriKind.Relative);
      HttpRequestMessage reqMessage = new HttpRequestMessage("POST", doWork, content);
  
      http.SendCompleted += AsnycSendComplete;
  
      http.SendAsync(reqMessage);
  
  
  static void AsnycSendComplete(object sender, SendCompletedEventArgs eSendCompletedEventArgs)
  {
      SampleResponseBody respBody = null;
  
      respBody = eSendCompletedEventArgs.Response.Content.ReadAsDataContract();
  
      Console.WriteLine("AsnycSendComplete " + respBody.Value);
  }

In the Async invocation the developer creates the HttpRequestMessage, supplies a delegate callback function, in the example "AsyncSendComplete", and then calls SendAsync. Like the synchronous functions a single class, in this case the SendCompletedEventArgs, returns the Content and the status of the invocation.

Conclusion

REST has become a fixture in the Microsoft product line. First becoming part of WCF, then part of some strategic products, and finally settling in the Microsoft REST Starter Kit. An intuitive set of classes shipping with the Starter Kit, make REST construction accessible to any .NET developer.