import java.io.*;
import java.net.*;
class UDPServer {
  public static void main(String args[]) throws Exception
  {

// Explicitly create array of bytes to hold message data
    byte[] receiveData = new byte[1024];
    byte[] sendData = new byte[1024];

// Create server datagram socket addressed by port 9876
    DatagramSocket serverSocket = new DatagramSocket(9876);
    System.out.println("Server Ready for Datagrams");

    while(true)
    {

// Create message datagram to hold data from client
      DatagramPacket receivePacket = new DatagramPacket(
      receiveData, receiveData.length);

// Receive from client
      serverSocket.receive(receivePacket);



// Create a string from the data received
      String sentence = new String(receivePacket.getData());
      System.out.println("Client sent: " + sentence);

// Get IP address and port of the client
	  InetAddress IPAddress = receivePacket.getAddress();
	  int port = receivePacket.getPort();

	  String capitalizedSentence = sentence.toUpperCase();
	  sendData = capitalizedSentence.getBytes();

// Create message datagram from data and client addressing information
	  DatagramPacket sendPacket =new DatagramPacket(
      sendData, sendData.length,
      IPAddress, port);

// Send to client
	  serverSocket.send(sendPacket);

	} // end while, loop to receive another message from the client
  } // end main
} // end class