ASP.NET 4 Unleashed

Creating an Asynchronous HTTP Handler

When you create an HTTP Handler by creating either a Generic Handler or implementing the IHttpHandler interface, you are creating a synchronous handler. In this section, you learn how to create an asynchronous handler.

The advantage of creating an asynchronous handler is scalability. The ASP.NET Framework maintains a limited pool of threads that are used to service requests. When ASP.NET Framework receives a request for a file, it assigns a thread to handle the request. If ASP.NET Framework runs out of threads, the request is queued until a thread becomes available. If too many threads are queued, the framework rejects the page request with a 503—Server Too Busy response code.

If you execute an HTTP Handler ...