The NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object) method starts asynchronously reading data from the incoming network buffers. Calling the NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object) method gives you the ability to receive data within a separate execution thread.

You must create a callback method that implements the AsyncCallback delegate and pass its name to the NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object) method. At the very minimum, your state parameter must contain the System.Net.Sockets.NetworkStream. Because you will want to obtain the received data within your callback method, you should create a small class or structure to hold a read buffer and any other useful information. Pass the structure or class instance to the NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object) method through the state parameter.

Your callback method should call the NetworkStream.EndRead(IAsyncResult) method. When your application calls NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object), the system will wait until data is received or an error occurs, and then the system will use a separate thread to execute the specified callback method, and blocks on NetworkStream.EndRead(IAsyncResult) until the provided System.Net.Sockets.NetworkStream reads data or throws an exception. If you want the original thread to block after you call the NetworkStream.BeginRead(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.

The NetworkStream.BeginRead(Byte[], int, int, AsyncCallback, object) method reads as much data as is available, up to the number of bytes specified by the size parameter.

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.