Skip to content
Snippets Groups Projects
Commit ae609dbf authored by Terry D. Norbraten's avatar Terry D. Norbraten
Browse files

no object creation in loops, use NIO

parent 129c5bda
No related branches found
No related tags found
No related merge requests found
Hide whitespace changes
Inline Side-by-side
examples/src/UdpMulticastHttpExamples/MulticastReceiver.java
+ 75
− 55
View file @ ae609dbf
package UdpMulticastHttpExamples;
import edu.nps.moves.dis7.utilities.DisThreadedNetIF;
import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Looks a lot like UdpReceiver. Start this before launching MulticastSender.
* Looks a lot like UdpReceiver. Start this before launching MulticastSender.
*
* @author mcgredo
* @author brutzman
......@@ -14,81 +18,97 @@ public class MulticastReceiver {
// 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
public static final String MULTICAST_ADDRESS = "239.1.2.15";
public static final int DESTINATION_PORT = 1718;
/** Time to live: how many router-decrement levels can be crossed */
public static final int TTL = 10;
final private static boolean infiniteReadLoop = true;
public static void main(String[] args)
{
try
{
System.out.println("MulticastReceiver started...");
public static final String MULTICAST_ADDRESS = "239.1.2.15";
public static final int DESTINATION_PORT = 1718;
/**
* Time to live: how many router-decrement levels can be crossed
*/
public static final int TTL = 10;
private static final boolean INFINITE_READ_LOOP = true;
private static NetworkInterface ni;
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("MulticastReceiver 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 multicastSocket = new MulticastSocket(DESTINATION_PORT);
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(multicastAddress);
multicastSocket.joinGroup(group, ni = DisThreadedNetIF.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 count = 0; // initialize
while(true)
{
byte[] packetArray = new byte[1500]; // note use of typical MTU value
DatagramPacket packet = new DatagramPacket(packetArray, packetArray.length);
int index, count = 0; // initialize
float firstFloat, secondFloat;
StringBuilder firstCharacters = new StringBuilder();
char nextChar;
while (true) {
multicastSocket.receive(packet);
count++;
ByteArrayInputStream bais = new ByteArrayInputStream(packet.getData());
DataInputStream dis = new DataInputStream(bais);
String firstCharacters = new String();
char nextChar = ' ';
while (nextChar != ';') // read and build string until terminator ; found
{
nextChar = dis.readChar();
firstCharacters += nextChar;
}
if (firstCharacters.contains(MulticastSender.QUIT_SENTINEL))
{
System.out.println("Received sentinel \"" + MulticastSender.QUIT_SENTINEL + "\"");
if (!infiniteReadLoop)
nextChar = ' ';
while (nextChar != ';') // read and build string until terminator ; found
{
nextChar = buffer.getChar();
firstCharacters.append(nextChar);
}
if (firstCharacters.toString().contains(MulticastSender.QUIT_SENTINEL)) {
System.out.println("Received sentinel \"" + MulticastSender.QUIT_SENTINEL + "\"");
if (!INFINITE_READ_LOOP) {
break; // exit out of reading loop
}
int index = dis.readInt();
float firstFloat = dis.readFloat();
float secondFloat = dis.readFloat();
if (count < 10) System.out.print(" "); // prettier output formatting
}
}
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);
}
}
catch(IOException e)
} catch (IOException e) {
System.err.println("Problem with MulticastReceiver, see exception trace:");
System.err.println(e);
} finally // clean up after exit condition
{
System.out.println("Problem with MulticastReceiver, see exception trace:");
System.out.println(e);
}
finally // clean up after exit condition
{
// socket/database/completion cleanup code can go here, if needed.
if (multicastSocket != null && !multicastSocket.isClosed()) {
try {
multicastSocket.leaveGroup(group, ni);
} catch (IOException ex) {
Logger.getLogger(MulticastReceiver.class.getName()).log(Level.SEVERE, null, ex);
}
multicastSocket.close();
}
// socket/database/completion cleanup code can go here, if needed.
System.out.println("MulticastReceiver finally block, complete.");
}
}
}
}
examples/src/UdpMulticastHttpExamples/MulticastSender.java
+ 49
− 35
View file @ ae609dbf
package UdpMulticastHttpExamples;
import edu.nps.moves.dis7.utilities.DisThreadedNetIF;
import java.io.*;
import java.net.*;
......@@ -28,9 +29,17 @@ public class MulticastSender {
public static final String QUIT_SENTINEL = "QUIT QUIT QUIT!";
@SuppressWarnings("SleepWhileInLoop")
public static void main(String[] args)
@SuppressWarnings("SleepWhileInLoop")
public static void main(String[] args) throws IOException
{
MulticastSocket multicastSocket = 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("MulticastSender started...");
......@@ -42,53 +51,58 @@ public class MulticastSender {
System.setProperty("java.net.preferIPv4Stack", "true");
// multicast group we are sending to--not a single host
MulticastSocket multicastSocket = new MulticastSocket(DESTINATION_PORT);
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);
InetSocketAddress group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
// Join group useful on receiving side
multicastSocket.joinGroup(multicastAddress);
multicastSocket.joinGroup(group, DisThreadedNetIF.findIpv4Interface());
// You can join multiple groups here
DatagramPacket packet;
byte[] buffer;
for (int index = 0; index < LOOPSIZE; index++)
{
// 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);
// Put together an updated packet to send
if (index < LOOPSIZE - 1)
{
// Put together an updated packet to send
dos.writeChars(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.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 = new DatagramPacket(buffer, buffer.length, multicastAddress, DESTINATION_PORT);
// Put together an updated packet to send
if (index < LOOPSIZE - 1)
{
// Put together an updated packet to send
dos.writeChars(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.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
byte[] buffer = baos.toByteArray();
DatagramPacket packet = new DatagramPacket(buffer, buffer.length, multicastAddress, DESTINATION_PORT);
multicastSocket.send(packet);
System.out.println("Sent multicast packet " + index + " of " + LOOPSIZE);
// 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
multicastSocket.send(packet);
System.out.println("Sent multicast packet " + index + " 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.out.println("Problem with MulticastSender, see exception trace:");
System.out.println(e);
if (multicastSocket != null)
multicastSocket.close();
dos.close();
System.err.println("Problem with MulticastSender, see exception trace:");
System.err.println(e);
}
}
......
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment