SslStream.BeginWrite Method

void ReadCallback(IAsyncResult ar)
{
    ClientState state = (ClientState) ar.AsyncState;
    SslStream stream = state.stream;
    // Read the  message sent by the client. 
    // The end of the message is signaled using the 
    // "<EOF>" marker.
    int byteCount = -1;
    try 
    {
        Console.WriteLine("Reading data from the client.");
        byteCount = stream.EndRead(ar);
        // Use Decoder class to convert from bytes to UTF8 
        // in case a character spans two buffers.
        Decoder decoder = Encoding.UTF8.GetDecoder();
        char[] chars = new char[decoder.GetCharCount(state.buffer,0, byteCount)];
        decoder.GetChars(state.buffer, 0, byteCount, chars,0);
        state.readData.Append (chars);
        // Check for EOF or an empty message. 
        if (state.readData.ToString().IndexOf("<EOF>") == -1 && byteCount != 0)
        {
            // We are not finished reading. 
            // Asynchronously read more message data from  the client.
            stream.BeginRead(state.buffer, 0, state.buffer.Length, 
                new AsyncCallback(ReadCallback),
                state);
        } 
        else
        {
            Console.WriteLine("Message from the client: {0}", state.readData.ToString());
        }

        // Encode a test message into a byte array. 
        // Signal the end of the message using "<EOF>".
        byte[] message = Encoding.UTF8.GetBytes("Hello from the server.<EOF>");
        // Asynchronously send the message to the client.
        stream.BeginWrite(message, 0, message.Length, 
            new AsyncCallback(WriteCallback),
            state);
    }
    catch (Exception readException)
    {
        Console.WriteLine("Read error: {0}", readException.Message);
        state.Close();
        return;
    }
}