Thread: Socket Programming (Handing mulitple connections help)

I have created a simple basic program that uses sockets but it can only handle one connection, how do I make it so it handles multiple connections?

Server code:

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = "";
            string message;
            byte[] buffer=new byte[250];
            IPHostEntry local = Dns.GetHostByName(Dns.GetHostName());
            IPEndPoint iep = new IPEndPoint(local.AddressList[0],8000);
            Socket newServer = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            newServer.Bind(iep);
            newServer.Listen(10);
            Socket newClient = newServer.Accept();



            if (newClient.Connected)
            {
                newClient.Receive(buffer);
                message = Encoding.ASCII.GetString(buffer);
                Console.WriteLine(message);
                newClient.Send(Encoding.ASCII.GetBytes("Hello client"));

            }
            



            newClient.Close();

           
        }
    }
}

client code:

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int number=1;
            string messageClient;
            byte[] bufferClient=new byte[200];
            IPAddress ip = IPAddress.Parse("192.168.30.127");
            IPEndPoint ie = new IPEndPoint(ip, 8000);
            Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            client.Connect(ie);
            
                if (client.Connected)
                {
                    client.Send(Encoding.ASCII.GetBytes("hello server"));
                    client.Receive(bufferClient);
                    messageClient = Encoding.ASCII.GetString(bufferClient);
                    Console.WriteLine(messageClient);
                }
            
           

            client.Close();
           
        }
    }
}

you need to put your call to accept() inside a while loop, and spawn a thread for each new connection that you receive.

Originally Posted by Elkvis

you need to put your call to accept() inside a while loop, and spawn a thread for each new connection that you receive.

ahh okay thanks, what do you mean by thread though, if i wanted to keep track of each single connection could i put them in a dictionary or list of sockets?

Originally Posted by shivam1992

ahh okay thanks, what do you mean by thread though

a thread is a lightweight process. look at the System.Threading.Thread class.

Originally Posted by shivam1992

if i wanted to keep track of each single connection could i put them in a dictionary or list of sockets?

you certainly could, but if you're using threads as I suggest, make sure to follow good thread safety practices, so that only one thread tries to access the collection of sockets at once.

If you're intending to have many clients connecting to your server at the same time I recommend you avoid "thread per client" as it will end up slowing your computer down. Instead you could consider a non-blocking solution which would forego the need for additional threads at all.

a single-threaded non-blocking model may be better for performance on the server machine, but the perceived performance by the clients could be much much worse. if two clients try to make a request at the same time, one will have to wait for the other while it finishes this could be unpleasant for the clients on long-running requests. one possible solution for this is to spawn a thread for each request, but monitor the raw sockets with a polling loop.