import java.io.*;
import java.util.Enumeration;
import java.util.Vector;
import net.jxta.peergroup.PeerGroup;
import net.jxta.peergroup.PeerGroupFactory;
import net.jxta.exception.PeerGroupException;
import net.jxta.document.AdvertisementFactory;
import net.jxta.document.Advertisement;
import net.jxta.discovery.DiscoveryService;
import net.jxta.pipe.PipeService;
import net.jxta.protocol.PeerGroupAdvertisement;
// HungryPeer tries to find a restaurant to
// get a good meal. It finds all RestoPeers in
// the RestoNet peergroup and (in later examples)
// requests bids from them.
public class HungryPeer {
private PeerGroup netpg = null; // NetPeergroup
private PeerGroup restoNet = null; // Resto Peergroup
private int timeout = 3000; // Timeout; can be adjusted
// Services within the RestoNet Peergroup
private DiscoveryService disco; // Discovery Service
private PipeService pipes; // Pipe Service
// Vector of discovered RestoPeers
private Vector restaurantAdvs = new Vector();
public static void main(String args[]) {
HungryPeer myapp = new HungryPeer();
myapp.startJxta();
System.exit(0);
}
// Start the JXTA application
private void startJxta() {
try {
// Discover (or create) and join the default jxta NetPeerGroup
netpg = PeerGroupFactory.newNetPeerGroup();
} catch (PeerGroupException e) {
// Couldn't initialize; can't continue
System.out.println("Fatal error : creating the net PeerGroup");
System.exit(1);
}
// Discover and join the RestoNet Peergroup
// HungryPeers never create the RestoNet peergroup
try {
if (!joinRestoNet()) {
System.out.println("Sorry could not find the RestoNet Peergroup");
System.exit(2);
}
} catch (Exception e) {
System.out.println("Can't join RestoNet group");
System.exit(1);
}
}
// This method is used to discover the RestoNet Peergroup.
// If found the peer will join the peergroup
private boolean joinRestoNet() {
int count = 3; // maximum number of attempts to discover
System.out.println("Attempting to discover the RestoNet Peergroup");
// Get the Discovery service handle from the NetPeerGroup
DiscoveryService hdisco = netpg.getDiscoveryService();
// All discovered RestoNet Peers
Enumeration ae = null;
// Loop until we find the "RestoNet" Peergroup advertisement
// or we've exhausted the desired number of attempts
while (count-- > 0) {
try {
// Check if we have the advertisement in the local
// peer cache
ae = hdisco.getLocalAdvertisements(DiscoveryService.GROUP,
"Name", "RestoNet");
// If we found the RestoNet advertisement, we are done
if ((ae != null) && ae.hasMoreElements())
break;
// The RestoNet advertisement is not in the local
// cache . Send a discovery request to search for it.
hdisco.getRemoteAdvertisements(null,
DiscoveryService.GROUP, "Name", "RestoNet", 1, null);
// Wait to give peers a chance to respond
try {
Thread.sleep(timeout);
} catch (InterruptedException ie) {}
} catch (IOException e) {
// Found nothing! Move on.
}
}
// Check if we found the RestoNet advertisement
if (ae == null || !ae.hasMoreElements()) {
return false;
}
System.out.println("Found the RestoNet PeerGroup Advertisement");
// Get the advertisement
PeerGroupAdvertisement adv =
(PeerGroupAdvertisement) ae.nextElement();
try {
// Call the PeerGroup Factory to instantiate a new
// peergroup instance
restoNet = netpg.newGroup(adv);
} catch (Exception e) {
System.out.println("Could not create RestoPeerGroup");
return false;
}
try {
// Call the PeerGroup Factory to instantiate a new
// peergroup instance
restoNet = netpg.newGroup(adv);
// Get the Discovery and Pipe services to
// be used within the RestoNet Peergroup
disco = restoNet.getDiscoveryService();
pipes = restoNet.getPipeService();
} catch (Exception e) {
System.out.println("Could not create RestoPeerGroup");
return false;
}
System.out.println("The HungryPeer joined the restoNet PeerGroup");
return true;
}
}
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