Uber cool Russell, Rickard you copy that?
marc
[EMAIL PROTECTED] wrote:
>
> marc fleury wrote:
> > Then don't tease us and can you GPL-spare that "multicast socket" code?
> > the idea is that a "new born" JNP client should be able to find his
> > provider by crying on the network "where is my MOM"?. AFAIK if the
> > naming is bootp'd then we are all set.
>
> Ok, ok, here ya go! Enjoy! Basically, all I'm doing is creating
> an extremely simple Message class. I serialize this and send it
> out the multicast socket. Both client and server do this, so it
> doesn't matter which comes up first (the client resends its packet
> when it receives a broadcast from a server).
>
> The server receives a broadcast message from a client and looks up
> the senders address in a config file. If found, all my app needs
> to do is connect to the client via RMI. Hope that isn't too
> confusing. The "server" here is a monitor/controller and the
> "client" is the source of data, the RMI server.
>
> public class Message implements Serializable
> {
> public Message(String source, String content)
> {
> this.source = source;
> this.content = content;
> }
>
> public String content;
> public String source;
> }
>
> public interface BroadcastConstants
> {
> static final String GROUP = "239.2.3.9";
> static final int PORT = 3333;
> static final int TTL = 1;
> }
>
> public class BroadcastClient implements Runnable, BroadcastConstants
> {
> public BroadcastClient()
> {
> try
> {
> group = InetAddress.getByName(GROUP);
>
> sock = new MulticastSocket(PORT);
> sock.setTimeToLive(TTL);
> sock.joinGroup(group);
>
> // set a receive timeout to periodically check for shutdown
> sock.setSoTimeout(200);
> }
> catch ( Exception e )
> {
> e.printStackTrace();
> }
> }
>
> /**
> * Broadcast a packet announcing our presence
> */
> private void announce() throws IOException
> {
> Message pkg = new Message("client", announce);
>
> ByteArrayOutputStream baos = new ByteArrayOutputStream();
> ObjectOutputStream oos = new ObjectOutputStream(baos);
> oos.writeObject(pkg);
>
> byte[] msg = baos.toByteArray();
> DatagramPacket pkt = new DatagramPacket(msg, msg.length, group, PORT);
> sock.send(pkt);
> }
>
> /**
> * Listen for server announcements
> */
> private void listen() throws IOException
> {
> byte[] recvBuffer = new byte[5000];
> DatagramPacket recv = new DatagramPacket(recvBuffer, recvBuffer.length);
>
> try
> {
> sock.receive(recv);
> }
> catch ( InterruptedIOException ie )
> {
> return;
> }
>
> byte[] buf = new byte[5000];
> System.arraycopy(recvBuffer, 0, buf, 0, recv.getLength());
>
> try
> {
> ObjectInputStream ois = new ObjectInputStream( new
> ByteArrayInputStream(buf) );
> Message msg = (Message) ois.readObject();
>
> // a server just came online -- resend my announcement
> if ( msg.source.equals("server") )
> {
> announce();
> }
> }
> catch (ClassNotFoundException cnf) { }
> }
>
> public void run()
> {
> try
> {
> announce();
> }
> catch (IOException e)
> {
> e.printStackTrace();
> return;
> }
>
> while (! stopping)
> {
> try
> {
> listen();
> }
> catch (IOException ioe)
> {
> ioe.printStackTrace();
>
> if (sock.getPort() == -1)
> { // connection lost
> System.exit(1);
> }
> }
> }
> }
>
> public void shutdown()
> {
> stopping = true;
> }
>
> private boolean stopping = false;
>
> private InetAddress group;
> private MulticastSocket sock;
>
> private static final String announce = "Client announce";
> }
>
> public class BroadcastServer implements Runnable, BroadcastConstants
> {
> public BroadcastServer(ServiceHandler handler)
> {
> try
> {
> group = InetAddress.getByName(GROUP);
>
> sock = new MulticastSocket(PORT);
> sock.setTimeToLive(TTL);
> sock.joinGroup(group);
> }
> catch (Exception e)
> {
> e.printStackTrace();
> System.exit(1);
> }
>
> this.handler = handler;
> }
>
> public void run()
> {
> // first, send out an announcement that I'm here
> // in case there are clients waiting
> Message msg = new Message("server", announce);
>
> try
> {
> ByteArrayOutputStream baos = new ByteArrayOutputStream();
> ObjectOutputStream oos = new ObjectOutputStream(baos);
> oos.writeObject(msg);
> oos.flush();
>
> byte[] msgData = baos.toByteArray();
> DatagramPacket pkt = new DatagramPacket(msgData, msgData.length,
> group, PORT);
> sock.send(pkt);
> }
> catch (Exception e)
> {
> e.printStackTrace();
> System.exit(1);
> }
>
> // now, wait for service requests from clients
> byte[] recvBuffer = new byte[5000];
> while ( true )
> {
> try
> {
> DatagramPacket recv = new DatagramPacket(recvBuffer,
> recvBuffer.length);
> sock.receive(recv);
>
> InetAddress recvAddr = recv.getAddress();
>
> byte[] buf = new byte[5000];
> System.arraycopy(recvBuffer, 0, buf, 0, recv.getLength());
>
> ObjectInputStream ois = new ObjectInputStream( new
> ByteArrayInputStream(buf) );
> Message m = (Message) ois.readObject();
>
> if ( m.source.equals("client") )
> {
> handler.service(recvAddr.getHostName());
> }
> }
> catch ( Exception e )
> {
> e.printStackTrace();
> }
> }
> }
>
> private ServiceHandler handler;
>
> private static InetAddress group;
> private static MulticastSocket sock;
>
> private static final String announce = "Server announce";
> }
>
> public interface ServiceHandler
> {
> /**
> * Service an announcement from a client at address
> */
> public void service(String address);
> }
>
> --
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