Homework 2

assignments/src/MV3500Cohort2023MarchJune/homework2/Hedgcorth/MulticastUdpReceiver.java

@@ -13,21 +13,23 @@ import java.util.logging.Logger;
 
 /**
  * Looks a lot like UdpReceiver. Start this before launching MulticastSender.
+ * Modified to close after sending 30 packets.
  *
  * @author leahhedgcorth
  */
-public class MulticastUdpReceiver
-{
-    /** Default constructor */
-    public MulticastUdpReceiver()
-    {
+public class MulticastUdpReceiver {
+
+    /**
+     * Default constructor
+     */
+    public MulticastUdpReceiver() {
         // default constructor
     }
     // reserved range for all IPv4 multicast: 224.0.0.0 through 239.255.255.255
     // https://en.wikipedia.org/wiki/Multicast_address
     // https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml
     private static final String MULTICAST_ADDRESS = "239.1.2.15";
-    private static final int     DESTINATION_PORT = 1718;
+    private static final int DESTINATION_PORT = 1718;
 
     /**
      * Time to live: how many router-decrement levels can be crossed
@@ -39,15 +41,15 @@ public class MulticastUdpReceiver
 
     /**
      * Program invocation, execution starts here
+     *
      * @param args command-line arguments
      */
-    public static void main(String[] args)
-    {
+    public static void main(String[] args) {
         MulticastSocket multicastSocket = null;
         InetSocketAddress group = null;
         ByteBuffer buffer = ByteBuffer.allocate(1500);
         DatagramPacket packet = new DatagramPacket(buffer.array(), buffer.capacity());
-        
+
         try {
             System.out.println("UdpExamples.MulticastUdpReceiver started...");
 
@@ -61,13 +63,13 @@ public class MulticastUdpReceiver
             multicastSocket = new MulticastSocket(DESTINATION_PORT);
             multicastSocket.setTimeToLive(TTL);
             InetAddress multicastAddress = InetAddress.getByName(MULTICAST_ADDRESS);
-            
+
             group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
-            
+
             // Join group useful on receiving side
             multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface());
             // You can join multiple groups here
-            
+
             System.out.println("Multicast address/port: " + multicastAddress.getHostAddress() + "/" + DESTINATION_PORT);
             System.out.println("Multicast packets received log:");
 

assignments/src/MV3500Cohort2023MarchJune/homework2/Hedgcorth/MulticastUdpSender.java

-
 package MV3500Cohort2023MarchJune.homework2.Hedgcorth;
 
 import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
@@ -14,60 +13,78 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 /**
- * Looks a lot like UdpSender.  Start this after launching MulticastReceiver.
- * 
- * Privacy note: this sender advertises your user name as part of the multicast packet message
- * 
+ * Looks a lot like UdpSender. Start this after launching MulticastReceiver.
+ * Modified to close after sending 30 packets.
+ *
+ * Privacy note: this sender advertises your user name as part of the multicast
+ * packet message
+ *
  *
  * @author leahhedgcorth
  */
 public class MulticastUdpSender {
-    
-    /** Default constructor */
-    public MulticastUdpSender()
-    {
+
+    /**
+     * Default constructor
+     */
+    public MulticastUdpSender() {
         // default constructor
     }
     // reserved range for all IPv4 multicast: 224.0.0.0 through 239.255.255.255
     // https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml
 
-    /** Default multicast group address for send and receive connections.
-     * @see <a href="https://en.wikipedia.org/wiki/Multicast_address">https://en.wikipedia.org/wiki/Multicast_address</a> */
+    /**
+     * Default multicast group address for send and receive connections.
+     *
+     * @see
+     * <a href="https://en.wikipedia.org/wiki/Multicast_address">https://en.wikipedia.org/wiki/Multicast_address</a>
+     */
     public static final String MULTICAST_ADDRESS = "239.1.2.15"; // within reserved multicast address range
-    /** Default socket port used, matches Wireshark DIS capture default
-     * @see <a href="https://en.wikipedia.org/wiki/Port_(computer_networking)">https://en.wikipedia.org/wiki/Port_(computer_networking)</a> */
-    public static final int     DESTINATION_PORT = 1718;
-    
-    /** Time to live: how many router-decrement levels can be crossed */
+    /**
+     * Default socket port used, matches Wireshark DIS capture default
+     *
+     * @see
+     * <a href="https://en.wikipedia.org/wiki/Port_(computer_networking)">https://en.wikipedia.org/wiki/Port_(computer_networking)</a>
+     */
+    public static final int DESTINATION_PORT = 1718;
+
+    /**
+     * Time to live: how many router-decrement levels can be crossed
+     */
     public static final int TTL = 10;
-	
-    /** How many packets to send prior to termination */
-    public static final int LOOPSIZE = 20; // or maybe 20000
-    
-    /** Receiving this message causes termination
-     * @see <a href="https://en.wikipedia.org/wiki/Sentinel_value">https://en.wikipedia.org/wiki/Sentinel_value</a> */
+
+    /**
+     * How many packets to send prior to termination
+     */
+    public static final int LOOPSIZE = 30; // or maybe 20000
+
+    /**
+     * Receiving this message causes termination
+     *
+     * @see
+     * <a href="https://en.wikipedia.org/wiki/Sentinel_value">https://en.wikipedia.org/wiki/Sentinel_value</a>
+     */
     public static final String QUIT_SENTINEL = "QUIT QUIT QUIT!";
     private static NetworkInterface ni;
-    
+
     /**
      * Program invocation, execution starts here
+     *
      * @param args command-line arguments
      * @throws java.io.IOException execution error
      */
     @SuppressWarnings("SleepWhileInLoop")
-    public static void main(String[] args) throws IOException 
-    {
+    public static void main(String[] args) throws IOException {
         MulticastSocket multicastSocket = null;
         InetSocketAddress group = null;
-        
+
         // 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);
-        
-        try
-        {
+        DataOutputStream dos = new DataOutputStream(baos);
+
+        try {
             System.out.println("UdpExamples.MulticastUdpSender started...");
             // This is a java/IPv6 problem. You should also add it to the
             // arguments used to start the app, eg -Djava.net.preferIPv4Stack=true
@@ -75,35 +92,33 @@ public class MulticastUdpSender {
             // 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");
-            
+
             // multicast group we are sending to--not a single host
             multicastSocket = new MulticastSocket(/*DESTINATION_PORT*/);
             multicastSocket.setTimeToLive(TTL); // time to live reduces scope of transmission
             InetAddress multicastAddress = InetAddress.getByName(MULTICAST_ADDRESS);
             System.out.println("Multicast address/port: " + multicastAddress.getHostAddress() + "/" + DESTINATION_PORT);
-            
+
             group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
             // Join group useful on receiving side
             multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface());
             // You can join multiple groups here
-            
+
             byte[] buffer = baos.toByteArray();
             DatagramPacket packet = new DatagramPacket(buffer, buffer.length, group/*, DESTINATION_PORT*/);
-            
-            for (int index = 0; index < LOOPSIZE; index++)
-            {
+
+            for (int index = 0; index < LOOPSIZE; index++) {
                 // Put together an updated packet to send
-                if (index < LOOPSIZE - 1)
-                {
+                if (index < LOOPSIZE - 1) {
                     // Put together an updated packet to send
                     dos.writeChars("From " + System.getProperty("user.name") + ": ");
                     dos.writeChars("MulticastSender packet " + Integer.toString(index) + ";"); // string chars for readability
-                    dos.writeInt  (index); // arbitrary data, needs Java or byte-alignment to read
+                    dos.writeInt(index); // arbitrary data, needs Java or byte-alignment to read
                     dos.writeFloat(17.0f); // arbitrary data, needs Java or byte-alignment to read
                     dos.writeFloat(23.0f); // arbitrary data, needs Java or byte-alignment to read
+                } else {
+                    dos.writeChars(QUIT_SENTINEL + ";"); // note string must include ; semicolon as termination sentinel
                 }
-                else dos.writeChars(QUIT_SENTINEL + ";"); // note string must include ; semicolon as termination sentinel
-                
                 buffer = baos.toByteArray();
                 packet.setData(buffer);
                 multicastSocket.send(packet);
@@ -118,13 +133,11 @@ public class MulticastUdpSender {
                 Thread.sleep(1000); // Send 100, one per second
             }
             System.out.println("MulticastSender complete.");
-        }
-        catch(IOException | InterruptedException e)
-        {
+        } catch (IOException | InterruptedException e) {
             System.err.println("Problem with MulticastSender, see exception trace:");
             System.err.println(e);
         } finally {
-            
+
             if (multicastSocket != null && !multicastSocket.isClosed()) {
                 try {
                     multicastSocket.leaveGroup(group, ni);
@@ -133,9 +146,9 @@ public class MulticastUdpSender {
                 }
                 multicastSocket.close();
             }
-            
+
             dos.close();
         }
     }
-    
+
 }