Converting the APM pattern to tasks

In this recipe, we will see how to convert an old-fashioned APM API to a task. There are examples of different situations that could happen in the process of conversion.

Getting ready

To start this recipe, you will need Visual Studio 2012. There are no other prerequisites. The source code for this recipe can be found at BookSamples\Chapter4\Recipe4.

How to do it...

For converting the APM pattern to tasks, perform the following steps:

1. Start Visual Studio 2012. Create a new C# Console Application project.

2. In the Program.cs file, add the following using directives:

   using System;
   using System.Threading;
   using System.Threading.Tasks;

3. Add the following code snippet below the Main method:

   private delegate string AsynchronousTask(stringthreadName);
   private delegate string IncompatibleAsynchronousTask(outint threadId);
   
   private static void Callback(IAsyncResultar){
     Console.WriteLine("Starting a callback...");
     Console.WriteLine("State passed to a callback: {0}",ar.AsyncState...