Hey hey hey
marc fleury wrote:
>
> Uber cool Russell, Rickard you copy that?
Yeah, only I already had this in the .cluster package that I had created
for testing. Although I also included a heartbeat to make sure that the
server was up. If someone Ctrl-C's the server there's no "I'm going down
now" message sent, so the other nodes had to use a heartbeat timeout to
detect it.
Although this is a bit redundant since I, now, realize that this is just
the sort of thing Jini does for you. And in a much better way.
:-)
/Rickard
>
> 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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>
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Rickard �berg
@home: +46 13 177937
Email: [EMAIL PROTECTED]
http://www.telkel.com
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