diff --git a/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpReceiver.java b/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpReceiver.java
new file mode 100644
index 0000000000000000000000000000000000000000..597349a4f8b46c323faed738e2dc9cba4d2c1235
--- /dev/null
+++ b/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpReceiver.java
@@ -0,0 +1,125 @@
+package MV3500Cohort2023MarchJune.homework2.Chojnacki;
+
+import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
+import java.io.*;
+import java.net.*;
+import java.nio.ByteBuffer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Modified the receiver to close after receiving 10 packets.
+ *
+ * @author Bruce Chojnacki
+ */
+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;
+
+ /**
+ * Time to live: how many router-decrement levels can be crossed
+ */
+ private static final int TTL = 10;
+
+ private static final boolean INFINITE_READ_LOOP = true;
+ private static NetworkInterface ni;
+
+ /**
+ * Program invocation, execution starts here
+ * @param args command-line arguments
+ */
+ 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...");
+
+ // 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 = 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:");
+
+ int index, count = 0; // initialize
+ float firstFloat, secondFloat;
+ StringBuilder firstCharacters = new StringBuilder();
+ char nextChar;
+
+ while (true) {
+ multicastSocket.receive(packet);
+ count++;
+
+ nextChar = ' ';
+ while (nextChar != ';') // read and build string until terminator ; found
+ {
+ nextChar = buffer.getChar();
+ firstCharacters.append(nextChar);
+ }
+ if (firstCharacters.toString().contains(MulticastUdpSender.QUIT_SENTINEL)) {
+ System.out.println("Received sentinel \"" + MulticastUdpSender.QUIT_SENTINEL + "\"");
+ if (!INFINITE_READ_LOOP) {
+ break; // exit out of reading loop
+ }
+ }
+ index = buffer.getInt();
+ firstFloat = buffer.getFloat();
+ secondFloat = buffer.getFloat();
+ buffer.clear();
+
+ if (count < 10) {
+ System.out.print(" "); // prettier output formatting
+ }
+ System.out.print(count + ". \"" + firstCharacters + "\" "); // wrap string in quote marks
+ System.out.println("index=" + index + ", firstFloat=" + firstFloat + " secondFloat=" + secondFloat);
+
+ System.out.println("MulticastReceiver loop complete.");
+ firstCharacters.setLength(0);
+ if (count >= 10) {
+ break;
+ }
+ }
+ } catch (IOException e) {
+ System.err.println("Problem with MulticastReceiver, see exception trace:");
+ System.err.println(e);
+ } finally // clean up after exit condition
+ {
+ if (multicastSocket != null && !multicastSocket.isClosed()) {
+ try {
+ multicastSocket.leaveGroup(group, ni);
+ } catch (IOException ex) {
+ Logger.getLogger(MulticastUdpReceiver.class.getName()).log(Level.SEVERE, null, ex);
+ }
+ multicastSocket.close();
+ }
+ // socket/database/completion cleanup code can go here, if needed.
+ System.out.println("MulticastReceiver has received all of the packets!");
+ }
+ }
+}
diff --git a/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpSender.java b/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpSender.java
new file mode 100644
index 0000000000000000000000000000000000000000..a61668e1f6fec5a2a0baa509247096b28a114491
--- /dev/null
+++ b/assignments/src/MV3500Cohort2023MarchJune/homework2/Chojnacki/MulticastUdpSender.java
@@ -0,0 +1,148 @@
+package MV3500Cohort2023MarchJune.homework2.Chojnacki;
+
+import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
+import java.io.*;
+import java.net.*;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Modified original code. The sender strings have been modified and include
+ * a time stamp.
+ *
+ * @author Bruce CHojnacki
+ */
+public class 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>
+ */
+ 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
+ */
+ public static final int TTL = 10;
+
+ /**
+ * How many packets to send prior to termination
+ */
+ public static final int LOOPSIZE = 10; // 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 = "I surrender!";
+ 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 {
+ 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 {
+ System.out.println("I am multicasting 10 packets...");
+ // 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");
+
+ // 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++) {
+ // Put together an updated packet to send
+ if (index < LOOPSIZE - 1) {
+ // Put together an updated packet to send
+
+ String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
+ dos.writeChars("We have found " + System.getProperty("user.name") + " at time: " + timeStamp + "\n");
+ dos.writeChars("MulticastSender packet " + Integer.toString(index) + ";"); // string chars for readability
+ 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
+ }
+ buffer = baos.toByteArray();
+ packet.setData(buffer);
+ multicastSocket.send(packet);
+ System.out.println("Sent multicast packet " + (index + 1) + " of " + LOOPSIZE);
+ baos.reset();
+
+ // 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? Necessary considerations.
+ Thread.sleep(1000); // Send 100, one per second
+ }
+ System.out.println("MulticastSender complete.");
+ } 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);
+ } catch (IOException ex) {
+ Logger.getLogger(MulticastUdpSender.class.getName()).log(Level.SEVERE, null, ex);
+ }
+ multicastSocket.close();
+ }
+
+ dos.close();
+ }
+ }
+
+}