using System;
using System.Net.Sockets;
using System.IO ;

public class Echoserver
{
	//entry point of main method....
	public static void Main()
	{
		//TcpListener is listening on the given port...							{
		TcpListener tcpListener = new TcpListener(1234);
    	tcpListener.Start();      
		Console.WriteLine("Server Started") ;			
		//Accepts a new connection...
		Socket socketForClient = tcpListener.AcceptSocket();			
      	//StreamWriter and StreamReader Classes for reading and writing the data to and fro.
      	//The server reads the meassage sent by the Client ,converts it to upper case and sends it back to the client.
      	//Lastly close all the streams.
        try
        {
      		if (socketForClient.Connected)
    	  	{
        	  	while(true)
        	  	{
        	  	Console.WriteLine("Client connected");
				NetworkStream networkStream = new NetworkStream(socketForClient);
            	StreamWriter streamWriter = new StreamWriter(networkStream);
 				StreamReader streamReader = new StreamReader(networkStream);
        	  	string line = streamReader.ReadLine();
    	  		Console.WriteLine("Read:" +line);
				line=line.ToUpper()+ "!";
				streamWriter.WriteLine(line);
				Console.WriteLine("Wrote:"+line);
      			streamWriter.Flush() ;        	  		
				 } 
    	  	}
		        socketForClient.Close();        	
                Console.WriteLine("Exiting...");
        }
        catch(Exception e)
        {
        	Console.WriteLine(e.ToString()) ;
        }
	}
}