The NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object) method starts an asynchronous send operation to the remote host. Calling the NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object) method gives you the ability to send data within a separate execution thread.

You must create a callback method that implements the AsyncCallback delegate and pass its name to the NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object) method. At the very minimum, your state parameter must contain the System.Net.Sockets.NetworkStream. If your callback needs more information, you can create a small class or structure to hold the System.Net.Sockets.NetworkStream and the other required information. Pass the structure or class instance to the NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object) method through the state parameter.

Your callback method should implement the NetworkStream.EndWrite(IAsyncResult) method. When your application calls NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object), the system uses a separate thread to execute the specified callback method, and blocks on NetworkStream.EndWrite(IAsyncResult) until the System.Net.Sockets.NetworkStream sends the number of bytes requested or throws an exception. If you want the original thread to block after you call the NetworkStream.BeginWrite(Byte[], int, int, AsyncCallback, object) method, use the System.Threading.WaitHandle.WaitOne(int, bool) method. Call System.Threading.EventWaitHandle.Set in the callback method when you want the original thread to continue executing. For additional information about writing callback methods, see Callback Sample.

Read and write operations can be performed simultaneously on an instance of the System.Net.Sockets.NetworkStream class without the need for synchronization. As long as there is one unique thread for the write operations and one unique thread for the read operations, there will be no cross-interference between read and write threads and no synchronization is required.