ASP.NET 4 Unleashed

Using Asynchronous ASP.NET Pages

When you take advantage of asynchronous ADO.NET methods, you must also enable asynchronous ASP.NET page execution. You enable an asynchronous ASP.NET page by adding the following two attributes to a page directive:

<%@ Page Async="true" AsyncTimeout="8" %>

The first attribute enables asynchronous page execution. The second attribute specifies a timeout value in seconds. The timeout value specifies the amount of time that the page gives a set of asynchronous tasks to complete before the page continues execution.

After you enable asynchronous page execution, you must set up the asynchronous tasks and register the tasks with the page. You represent each asynchronous task with an instance of the PageAsyncTask object. ...