SnellHW2

projects/Assignments/homework2/SnellMulticastClient.java

+/*
+ * 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.
+ */
+package HW2;
+
+import java.io.ByteArrayInputStream;
+import java.io.DataInputStream;
+import java.net.DatagramPacket;
+import java.net.InetAddress;
+import java.net.MulticastSocket;
+
+/**
+ *
+ * @author Justin Snell
+ */
+public class SnellMulticastClient {
+    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) 
+    {
+        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(DESTINATION_PORT);
+            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
+            
+            int count = 0;
+            
+            while(true)
+            {
+                byte[] packetArray = new byte[1500];
+                DatagramPacket packet = new DatagramPacket(packetArray, packetArray.length);
+                
+                multicastSocket.receive(packet);
+                count++;
+                
+                ByteArrayInputStream bais = new ByteArrayInputStream(packet.getData());
+                DataInputStream dis = new DataInputStream(bais);
+                int firstNumber = dis.readInt();
+                int secondNumber = dis.readInt();
+                
+                System.out.println("Number received: " + count + " xpos:" + firstNumber + " ypos:" + secondNumber);
+            }
+        }
+        catch(Exception e)
+        {
+            System.out.println(e);
+        }
+    }
+    
+}

projects/Assignments/homework2/SnellMulticastServer.java

+package HW2;
+
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.net.DatagramPacket;
+import java.net.InetAddress;
+import java.net.MulticastSocket;
+
+public class SnellMulticastServer {
+    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) 
+    {
+        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
+            
+            int xpos = 12;
+            int ypos = 15;
+            
+            // 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);
+            dos.writeInt(xpos);
+            dos.writeInt(ypos);
+            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 < 100; idx++)
+            {
+               multicastSocket.send(packet);
+               Thread.sleep(1000); // Send 100, one per second
+               System.out.println("Sent multicast packet " + idx + " of 100");
+            }
+        }
+        catch(Exception e)
+        {
+            System.out.println(e);
+        }
+    } 
+}