/*
 * DatagramDemo.java
 *
 * This class creates a datagram socket, listens for a message from another
 * system on it, and then prints the message to System.out
 *
 * Copyright (c) 2000 - Russell C. Bjork
 *
 */
 
import java.net.*;
import javax.swing.JOptionPane;

public class DatagramDemo
{
	public static void main(String [] args) throws Exception
	{
		// Create a datagram socket to receive data.  The system will choose
		// an ephemeral port
		
		DatagramSocket socket = new DatagramSocket();
		
		// Create a datagram packet to store the received data
		
		byte [] rawData = new byte [MAX_MESSAGE_SIZE];
		DatagramPacket packet = new DatagramPacket(rawData, MAX_MESSAGE_SIZE);
		
		// Receive the data
		
		JOptionPane.showMessageDialog(null, "Ready to receive a message at " +
			InetAddress.getLocalHost().getHostAddress() + 
			" port " + socket.getLocalPort());
		socket.receive(packet);
		
		// Write out the sender and information received
		
		InetAddress sender = packet.getAddress();
		JOptionPane.showMessageDialog(null, "Received message from: " + 
			sender.getHostName() +
			" [" + sender.getHostAddress() + "]\n" +
			new String(rawData, 0, 0, packet.getLength()));
	}

	private static final int MAX_MESSAGE_SIZE = 100;
}