Async / Await & AsyncController?

Question

Do you need to inherit from AsyncController when you use Async / Await in your controller or will not be asynchronous if you use the controller? How about asp.net web api? I do not think there is an AsyncApiController. Currently, I just inherit from the controller and its work, but is it really isync?

Answer 1

XML comment for AsyncController class in MVC 4 says

Provided for backward compatibility with ASP.NET MVC 3.

The class itself is empty.

In other words, you do not need it.

Answer 2

As for the Web API, you don't need the base class of the Async controller. All you have to do is wrap the return value in the Task.

For instance,

  /// <summary> /// Assuming this function start a long run IO task /// </summary> public Task<string> WorkAsync(int input) { return Task.Factory.StartNew(() => { // heavy duty here ... return "result"; } ); } // GET api/values/5 public Task<string> Get(int id) { return WorkAsync(id).ContinueWith( task => { // disclaimer: this is not the perfect way to process incomplete task if (task.IsCompleted) { return string.Format("{0}-{1}", task.Result, id); } else { throw new InvalidOperationException("not completed"); } }); } 

In addition, in .Net 4.5 you can use await-async to write even simpler codes:

  /// <summary> /// Assuming this function start a long run IO task /// </summary> public Task<string> WorkAsync(int input) { return Task.Factory.StartNew(() => { // heavy duty here ... return "result"; } ); } // GET api/values/5 public async Task<string> Get(int id) { var retval = await WorkAsync(id); return string.Format("{0}-{1}", retval, id); }