class Program
    {
        static void Main(string[] args)
        {
            TcpListener lsner = new TcpListener(9000);
            lsner.Start();
            Console.WriteLine("started in port: 9000");
            while (true)
            {
                TcpClient client=lsner.AcceptTcpClient();
                Console.WriteLine("new client received. hashcode: {0}", client.GetHashCode());
                ThreadPool.QueueUserWorkItem(new WaitCallback(ProcessTcpClient), client);
            }
            Console.ReadKey();
        }

        private static void ProcessTcpClient(object state)
        {
            TcpClient client=state as TcpClient;
            if(client==null)
                Console.WriteLine("client is null");

            NetworkStream ns=client.GetStream();
            StreamWriter sw = new StreamWriter(ns);
            sw.WriteLine("Welcome.");
            sw.Flush();
            sw.Close();
            client.Close();
        }

class Program
    {
        static void Main(string[] args)
        {
            IPAddress address = IPAddress.Parse("127.0.0.1");
            IPEndPoint ep=new IPEndPoint(address, 9000);
            TcpClient client = new TcpClient();
            client.Connect(ep);
            NetworkStream ns=client.GetStream();
            StreamReader sr = new StreamReader(ns);
            Console.WriteLine(sr.ReadToEnd());
            sr.Close();
            sr.Dispose();
            ns.Close();
            ns.Dispose();
            client.Close();
            Console.ReadKey();
        }
    }