<%@ WebHandler Language="C#" Class="Handler" %>

​

using System;

using System.Threading.Tasks;

using System.Web;

​

public class Handler : IHttpAsyncHandler

{

    public void ProcessRequest(HttpContext context)

    {

        context.Response.ContentType = "text/plain";

        context.Response.Write("Hello World");

    }

​

    public bool IsReusable

    {

        get { return false; }

    }

​

    public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)

    {

        var getTask = Work(context);

        var tcs = new TaskCompletionSource<object>(context);

        getTask.ContinueWith((t, o) =>

                             {

                                 if (t.IsFaulted)

​

                                 {

                                     if (t.Exception != null) tcs.SetException(t.Exception.InnerExceptions);

                                 }

                                 else

                                 {

                                     tcs.SetResult(null);

                                 }

​

                                 cb(tcs.Task);

                             },

                extraData);

​

​

        return tcs.Task;

    }

​

    public void EndProcessRequest(IAsyncResult result)

    {

        var t = (Task) result;

        var con = t.AsyncState as HttpContext;

        try

        {

            t.Wait(); //for exception

        }

        catch (Exception)

        {

            if (con != null) con.Response.Write("error");

        }

    }

​

​

    public async Task Work(HttpContext context)

    {

        await Task.Delay(100);

        throw new AggregateException();

        context.Response.Write("aaaaaa");

    }

}

​

​

​

​