import java.net.*;
import java.io.*;

public class MultiApp {

	public static void main( String [] args ) throws Exception {
		String myHost = "localhost";
		int myPort = 6789; // echo
		MulticastSocket ms = new MulticastSocket(6789);
		InetAddress group = InetAddress.getByName("228.5.6.7");
		ms.joinGroup( group );

		while ( true ) {

			String message = new java.util.Date().toString();
			byte [] data = message.getBytes();
			DatagramPacket pack = new DatagramPacket(data, data.length, 
				group, myPort );

			ms.send( pack, (byte)42 );

			pack = new DatagramPacket(new byte [1024], 1024);

			ms.receive( pack );

			System.out.println( "Echo from: " + 
				pack.getAddress().getHostName() + " - " 
				+ new String( pack.getData() ) );

			ms.receive( pack );

			System.out.println( "Echo from: " + 
				pack.getAddress().getHostName() + " - " 
				+ new String( pack.getData() ) );

			Thread.sleep(2000);
		}
	}
}