Question

We have web application , it works as Socket Listner. I wanted to check before the AcceptSocket , whether there is any Client Socket available to connect to this listner. I want to display a message if there is no Client Socket to connect and cancel send/receive of data.

I am using TCPListner using ASP.net C# for the web application. The Client socket is windows VB6 application using Winsock control.

Socketing programme, ASP.Net C#, VS2008

Thanks you for the reply ,

see below my sample code for communicate with server

clsCommunication.cs, this class file imports into .aspx page. I tried using Console.WriteLine(), but cann’t shown this message.

I wanted to display alert box , so that user understands there is no connection OR display on status bar or highlight a frame/box etc.

public void Communicationcation()
{
    byte[] bytes = new byte[1024];
    string strSiteID = "SiteID";

    socket.Start();
    if (!socket.Pending())
    {
        Console.WriteLine("Sorry, no connection requests have arrived");
    }
    else
    {
        client = socket.AcceptSocket();
        if (client.Connected == true)
        {
            decimal dSiteID = decimal.Parse(GetSiteSetting(ref strSiteID).ToString());
            IPEndPoint clientep = (IPEndPoint)client.RemoteEndPoint;

            WriteLog(string.Format("Connected with {0} at port {1}",  clientep.Address,  clientep.Port));
            string strWelcome = STARTMESSAGE + "WHOAMI" + "     " + dSiteID + " " + dSiteID + FINISHMESSAGE;
            byte[] data = new byte[1024];
            data = Encoding.ASCII.GetBytes(strWelcome);
            int i = client.Send(data, data.Length, SocketFlags.None);
            WriteLog(String.Format("Message sent {0} bytes!", i));

            //Get reply from the Connected cleint.
            i = client.Receive(bytes, bytes.Length, SocketFlags.None);
            if (i != -1)
            {
                WriteLog(string.Format(System.Text.Encoding.UTF8.GetString(bytes)));
            }
        }
    }
}

Answer 1

You can use TcpListener‘s Pending method, see http://msdn.microsoft.com/en-us/library/system.net.sockets.tcplistener.pending.aspx