Question

I am very very new to delegates!

I have an AsyncCallback delegate which runs a method.

This method periodically writes text to the console (Console.WriteLine(“FooBar”))

This delegate is kicked off from my Main method and I need to find a way to keep this Main method open while the delegate runs. Otherwise, the program starts, kicks off the delegate and closes again so I am using Console.Readline.

Will this work? Will my program be able to both sit at Console.ReadLine while my delegate periodically writes text to the console with Console.WriteLine or am I an idiot? My code is below:

static void Main(string[] args)
{
    NetworkStream myNetworkStream;
    Socket socket;
    IPEndPoint maxPort = new IPEndPoint(IPAddress.Parse("x.x.x.x"), xxxx);

    socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
    socket.Connect(maxPort);

    myNetworkStream = new NetworkStream(socket);

    byte[] buffer = new byte[1024];
    int offset = 0;
    int count = 1024;

    string loginString = "FOOBARR";
    ASCIIEncoding encoder = new ASCIIEncoding();

    myNetworkStream.BeginRead(buffer, offset, count, new AsyncCallback(OnBeginRead), myNetworkStream);
    myNetworkStream.Write(encoder.GetBytes(loginString), 0, encoder.GetByteCount(loginString));

    Console.ReadLine();
}

public static void OnBeginRead(IAsyncResult ar)
{
    NetworkStream ns = (NetworkStream)ar.AsyncState;
    int bufferSize = 2014;
    byte[] received = new byte[bufferSize];
    string result = String.Empty;

    ns.EndRead(ar);

    int read;

    while (true)
    {
        if (ns.DataAvailable)
        {
            read = ns.Read(received, 0, bufferSize);
            result += Encoding.ASCII.GetString(received);
            received = new byte[bufferSize];

            Console.WriteLine(result);
        }
        else
        {
            Thread.Sleep(1000);
        }
    }
}

Also, if I call ‘myNetworkStream.BeginRead’ multiple times with different parameters, will a different version of my ‘OnBeginRead’ method start each time on a seperate thread on the processor or will the method that was running stop and be replaced by the more recent one?

Answer 1

Will my program be able to both sit at Console.ReadLine while my delegate periodically writes >text to the console with Console.WriteLine?

Short answer: Yes

if I call ‘myNetworkStream.BeginRead’ multiple times with different
parameters will a different version of my ‘OnBeginRead’ method start
each time on a seperate thread on the processor or will the method
that was running stop and be replace by the more recent one

MSDN says this about calling BeginRead multiple times

Read and write operations can be performed simultaneously on an
instance of the 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.

Which implies that you shouldn’t call BeginRead from multiple threads. This will lead to unexpected behaviour