Async Controler

SampleAsyncController.cs

//.NET 4.0

//Synchronous Controller:
public class TestController : Controller
 {
   public ActionResult Index()
    {
     return View(); 
    }
 }
 
//Asynchronous variant of above operation:
public class TestController : AsyncController
{
   public void IndexAsync()
   {
    return View();
   }

  public ActionResult IndexCompleted()
  {
   return View();
  }
}

//Async with TPL
public class TestOutput
{
    public string One { get; set; }
    public string Two { get; set; }
    public string Three { get; set; }

    public static string DoWork(string input)
    {
        Thread.Sleep(2000);
        return input;
    }
}
public class TestController : AsyncController
{
  public void IndexAsync()
  {
      AsyncManager.OutstandingOperations.Increment(3);
  
      Task.Factory.StartNew(() => 
          { 
              return TestOutput.DoWork("1"); 
          })
          .ContinueWith(t => 
          { 
              AsyncManager.OutstandingOperations.Decrement(); 
              AsyncManager.Parameters["one"] = t.Result; 
          });
      Task.Factory.StartNew(() =>
          {
              return TestOutput.DoWork("2");
          })
          .ContinueWith(t =>
          {
              AsyncManager.OutstandingOperations.Decrement();
              AsyncManager.Parameters["two"] = t.Result;
          });
      Task.Factory.StartNew(() =>
          {
              return TestOutput.DoWork("3");
          })
          .ContinueWith(t =>
          {
              AsyncManager.OutstandingOperations.Decrement();
              AsyncManager.Parameters["three"] = t.Result;
          });
  }

  public ActionResult IndexCompleted(string one, string two, string three)
  {
      return View(new TestOutput { One = one, Two = two, Three = three });
  }
}

//Async controller in .NET 4.5

public async Task<ActionResult> Index() 
{
  // Start all three operations.
  var tasks = new[]
  {
    Task.Run(() =>TestOutput.DoWork("one")), 
    Task.Run(() =>TestOutput.DoWork("two")), 
    Task.Run(() =>TestOutput.DoWork("three"))
  };

  // Asynchronously wait for them all to complete.
  var results = await Task.WhenAll(tasks);

  // Retrieve the results.
  return View(new TestOutput
  {
    One = results[0],
    Two = results[1],
    Three = results[2]
  }); 
}