Question

Can anybody explain me what is the difference between the Begin[…]/End[…] asynchronous API pattern and the later […]Async pattern in .NET 3.5?

• Why was the later created?
• Why would one prefer one pattern over another?

For example, Socket.BeginAccept() and Socket.AcceptAsync().

Answer 1

MSDN will answer that better than me:

http://msdn.microsoft.com/en-us/library/system.net.sockets.socketasynceventargs.aspx

The main feature of these enhancements
is the avoidance of the repeated
allocation and synchronization of
objects during high-volume
asynchronous socket I/O. The Begin/End
design pattern currently implemented
by the System.Net.Sockets.Socket class
requires a System.IAsyncResult object
be allocated for each asynchronous
socket operation.