/*****************************
Para ejecutar:
1.- Instale Java Standard Edition development Kit (JDK)
si no lo tiene   http://java.sun.com
2.- Configure adecuadamente la
variable de ambiente PATH .
3.- Compile el programa con:
% javac UDPServer.java
4.- Ejecute el programa con:
% java UDPServer
*******************************/

import java.io.*; 
import java.net.*; 
  
class UDPServer { 
  public static void main(String args[]) throws Exception 
    {  
      DatagramSocket serverSocket = new DatagramSocket(9876);
      byte[] receiveData = new byte[1024]; 
      byte[] sendData  = new byte[1024];
      while(true) 
      {
        DatagramPacket receivePacket = 
          new DatagramPacket(receiveData, receiveData.length); 
        serverSocket.receive(receivePacket); 
        String sentence = new String(receivePacket.getData(),
                                     0, receivePacket.getLength());
        InetAddress IPAddress = receivePacket.getAddress();
        int port = receivePacket.getPort();
        String capitalizedSentence = sentence.toUpperCase();
        sendData = capitalizedSentence.getBytes();
        DatagramPacket sendPacket = 
          new DatagramPacket(sendData, sendData.length, IPAddress, 
                             port);
        serverSocket.send(sendPacket); 
      } 
    } 
}