/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ import java.io.ByteArrayOutputStream; import java.io.DataOutputStream; import java.net.DatagramPacket; import java.net.InetAddress; import java.net.MulticastSocket; /** * * @author Michael */ public class BlankenbekerMulticastSender { public static final String MULTICAST_ADDRESS = "239.1.2.15"; public static final int DESTINATION_PORT = 1717; /** How many routers can be crossed */ public static final int TTL = 10; public static void main(String[] args) { Truck truck = new Truck(); while (true) { truck.move(); try { // This is a java/IPv6 problem. You should also add it to the // arguments used to start the app, eg -Djava.net.preferIPv4Stack=true // set in the "run" section of preferences. Also, typically // netbeans must be restarted after these settings. // https://stackoverflow.com/questions/18747134/getting-cant-assign-requested-address-java-net-socketexception-using-ehcache System.setProperty("java.net.preferIPv4Stack", "true"); MulticastSocket multicastSocket = new MulticastSocket(1718); multicastSocket.setTimeToLive(TTL); InetAddress multicastAddress = InetAddress.getByName(MULTICAST_ADDRESS); System.out.println(multicastAddress); // Join group useful on receiving side multicastSocket.joinGroup(multicastAddress); // You can join multiple groups here // Put together a message with binary content. "ByteArrayOutputStream" // is a java.io utility that lets us put together an array of binary // data, which we put into the UDP packet. ByteArrayOutputStream baos = new ByteArrayOutputStream(); DataOutputStream dos = new DataOutputStream(baos); float x = truck.getX(); float y = truck.getY(); float z = truck.getZ(); dos.writeFloat(x); dos.writeFloat(y); dos.writeFloat(z); byte[] buffer = baos.toByteArray(); // Put together a packet to send // muticast group we are sending to--not a single host DatagramPacket packet = new DatagramPacket(buffer, buffer.length, multicastAddress, DESTINATION_PORT); // How fast does this go? Does UDP try to slow it down, or does // this cause network problems? (hint: yes for an unlimited send // rate, unlike TCP). How do you know on the receiving side // that you haven't received a duplicate UDP packet, out of // order packet, or dropped packet? for(int idx = 0; idx < 1; idx++) { multicastSocket.send(packet); Thread.sleep(1000); // Send 100, one per second System.out.println("Sent new multicast packet 1 of 1"); } } catch(Exception e) { System.out.println(e); } } } }