//***** ServerSocket

import java.net.Socket;
import java.net.ServerSocket;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
public class ReverseServer {
    public static void main(String[ ] args) {
        try {
            // Open a server socket on the designated port and
            // allow up to max_conn connections at a time.
            ServerSocket ssock = new ServerSocket(port, max_conn);
        
            // Indefinitely wait for and handle clients.
            while (true) {
               Socket sock = ssock.accept(); // accept() blocks

               // Read the request string from the client
               InputStreamReader isr = 
                 new InputStreamReader(sock.getInputStream());
               BufferedReader  in = new BufferedReader(isr);
               String req = in.readLine(); // blocks

               // Produce the response string.
               String res = 
                 new StringBuffer(req).reverse().toString();
               // Write the response to the client.
               PrintWriter out = 
                 new PrintWriter(sock.getOutputStream());
               out.println(res);
               out.flush();
               // Cleanup.
               sock.close();  // closes streams
            }
        }
        catch(IOException e) { System.err.println(e); }
    }
    private static final int port = 9876;
    private static final int max_conn = 100;
}