Question

I’m writing an application server that will maintain upwards of 2,000 long-term persistent client TCP connections. I’d like to know what the most efficient way to asynchronously accept the connections and read data from them is.

I essentially want to wrap all of the socket code in a class with a public footprint like this:

public partial class ApplicationClient
{
    private Socket socket;

    public ApplicationClient(Socket socket)
    {
        this.socket = socket;
    }

    public event ApplicationMessageEventHander MessageReceived;

    private void OnMessageReceived(string message)
    {
        ApplicationMessageEventHander messageReceived = this.MessageReceived;
        if (messageReceived != null)
        {
            var eventArgs = new ApplicationMessageEventArgs(message);
            messageReceived(this, eventArgs);
        }
    }
}

What’s the best way to use .NET’s sockets to fit this architecture?

EDIT: It’s also worth mentioning that each message passed by the client will be newline-terminated. I don’t want to fire the event until the entire message has been received.

Answer 1

You should use the BeginReceive and EndReceive functions. They take a parameter to an AsyncCallback delegate. You will then have to write some code that wraps that to handle your new line piece, and then you should call another delegate.

I believe something like this would be the appropriate way to handle it:

const uint buf_len = 40;
byte[] bBuffer;
string strBuffer;

public ApplicationClient(Socket socket)
{
    this.socket = socket;
    bBuffer = new byte[buf_len];
    strBuffer = "";
    socket.BeginReceive(buffer, 0, buf_len, 0, my_callback, null);
}

protected void AsyncCallback(IAsyncResult iar)
{
    int i;
    int bytesRead;
    string[] parts;

    bytesRead = socket.EndReceive(iar);

    if(read > 0)
    {
        strBuffer += Encoding.ASCII.GetString(buffer, 0, bytesRead);
        parts = strBuffer.split("\n");
        for(i = 0; i < parts.Length - 1; ++i)
        {
            theRealCallback(parts[i]);
        }
        strBuffer = parts[i];
    }

    socket.BeginReceive(buffer, 0, buf_len, 0, my_callback, null);
}