Client.cs

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace client
{
	class ProcessingServerClient
	{
		Socket io = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
		const uint bufferSize = 1024;
		readonly byte[] goodbyeMagic = { 0x42 };

		public void Connect ()
		{
			io.Connect ("localhost", 8080);
		}

		public void Disconnect ()
		{
			io.Send (goodbyeMagic);
			io.Close ();
		}

		public string requestResponse (String str)
		{
			byte[] buf = new byte[str.Length * sizeof (char)];
			System.Buffer.BlockCopy (str.ToCharArray (), 0, buf, 0, buf.Length);
			io.Send (buf);

			byte[] rbuf = new byte[bufferSize];
			int size = io.Receive(rbuf);
			byte[] response = new byte[size];
			System.Buffer.BlockCopy (rbuf, 0, response, 0, size);

			return System.Text.UnicodeEncoding.Unicode.GetString (response);
		}
	}

	class MainClass
	{
		public static void Main (string[] args)
		{
			ProcessingServerClient io = new ProcessingServerClient ();
			string r, request;

			Console.WriteLine ("Enter 'c' to send current time or enter a format string");
			r = Console.ReadLine ();
			if (r == "c")
				request = DateTime.Now.ToString ("yyyy-MM-d HH:mm:ss");
			else
				request = Console.ReadLine ();
			io.Connect ();
			Console.WriteLine ("Connected");
			r = io.requestResponse (request);
			io.Disconnect ();
			Console.WriteLine ("Response: " + r);
			Console.WriteLine ("Done");
			Console.ReadLine ();
		}
	}
}