Раздел «Технологии программирования».IAsyncResult:
IAsyncResult Interface

Represents the status of an asynchronous operation.

public interface IAsyncResult

Remarks The IAsyncResult interface is implemented by classes containing methods that can operate asynchronously. It is the return type of methods that initiate an asynchronous operation, such as BeginRead?, and is the type of the third parameter of methods that conclude an asynchronous operation, such as EndRead?. IAsyncResult objects are also passed to methods invoked by AsyncCallback delegates when an asynchronous operation completes.

An object that supports the IAsyncResult interface stores state information for an asynchronous operation, and provides a synchronization object to allow threads to be signaled when the operation completes.

See also:
AsyncProgrammingModule
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemiasyncresultmemberstopic.asp

-- AndreyUstyuzhanin - 06 Apr 2004