import java.io.*;import java.net.*;import java.util.*;import net.jxta.peergroup.PeerGroup;import net.jxta.peergroup.PeerGroupFactory;import net.jxta.peergroup.PeerGroupID;import net.jxta.exception.PeerGroupException;import net.jxta.discovery.DiscoveryService;import net.jxta.id.IDFactory;import net.jxta.pipe.PipeService;import net.jxta.protocol.PeerGroupAdvertisement;import net.jxta.protocol.ModuleImplAdvertisement;// RestoPeer represents a restaurant that receives auction requests// for food from HungryPeers. The RestoPeer will discover and join// the RestoNet and publish itself as a provider for HungryPeerspublic class RestoPeer {    private PeerGroup netpg = null;     // The NetPeerGroup    private PeerGroup restoNet = null;  // The RestoNet Peergroup    private String brand = "Chez JXTA";  // Brand of my restaurants    private int timeout = 3000;          // Timeout; can be adjusted    // Services within the RestoNet peergroup    private DiscoveryService disco = null;  // Discovery service    private PipeService pipes = null;       // Pipe service    static String groupURL = "jxta:uuid-4d6172676572696e204272756e6f202002";     public static void main(String args[]) {        RestoPeer myapp = new RestoPeer();        myapp.startJxta();        System.exit(0);    }    // start the JXTA application    private void startJxta() {        try {            // Discover and join (or start) the default peergroup            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 (or create) and join the RestoNet peergroup        try {            joinRestoNet();        } catch (Exception e) {            System.out.println("Can't join or create RestoNet");            System.exit(1);        }        // Wait for HungryPeers        System.out.println("Waiting for HungryPeers");        while (true) {            // In later examples, HungryPeer requests are processed here        }    }    // Discover (or crete) and join the RestoNet peergroup    private void joinRestoNet() throws Exception {        int count = 3;   // maximun number of attempts to discover        System.out.println("Attempting to Discover the RestoNet PeerGroup");        // Get the discovery service from the NetPeergroup        DiscoveryService hdisco = netpg.getDiscoveryService();        Enumeration ae = null;  // Holds the discovered peers        // Loop until we discover the RestoNet or        // until we've exhausted the desired number of attempts        while (count-- > 0) {            try {                // search first in the peer local cache to find                // the RestoNet peergroup advertisement                ae = hdisco.getLocalAdvertisements(DiscoveryService.GROUP,                                          "Name", "RestoNet");                // If we found the RestoNet advertisement we are done                if ((ae != null) && ae.hasMoreElements())                    break;                // If we did not find it, we send a discovery request                hdisco.getRemoteAdvertisements(null,                       DiscoveryService.GROUP, "Name", "RestoNet", 1, null);                // Sleep to allow time for peers to respond to the                // discovery request                try {                    Thread.sleep(timeout);                } catch (InterruptedException ie) {}            } catch (IOException e) {                // Found nothing! Move on.            }        }        PeerGroupAdvertisement restoNetAdv = null;        // Check if we found the RestoNet advertisement.        // If we didn't, then either        //       we are the first peer to join or        //       no other RestoNet peers are up.        // In either case, we must create the RestoNet peergroup        if (ae == null || !ae.hasMoreElements()) {            System.out.println(                 "Could not find the RestoNet peergroup; creating one");            try {                // Create a new, all-purpose peergroup.                ModuleImplAdvertisement implAdv =                    netpg.getAllPurposePeerGroupImplAdvertisement();                restoNet = netpg.newGroup(                                mkGroupID(),      // Assign new group ID                                implAdv,          // The implem. adv                                "RestoNet",       // Name of peergroup                                "RestoNet, Inc.");// Description of peergroup                // Get the PeerGroup Advertisement                restoNetAdv = netpg.getPeerGroupAdvertisement();            } catch (Exception e) {                System.out.println("Error in creating RestoNet Peergroup");                throw e;            }        } else {            // The RestoNet advertisement was found in the cache;            // that means we can join the existing RestoNet peergroup            try {                restoNetAdv = (PeerGroupAdvertisement) ae.nextElement();                restoNet = netpg.newGroup(restoNetAdv);                 System.out.println(                     "Found the RestoNet Peergroup advertisement; joined existing group");            } catch (Exception e) {                System.out.println("Error in creating RestoNet PeerGroup from existing adv");                throw e;            }        }        try {            // Get the discovery and pipe services for the RestoNet Peergroup            disco = restoNet.getDiscoveryService();            pipes = restoNet.getPipeService();        } catch (Exception e) {            System.out.println("Error getting services from RestoNet");            throw e;        }        System.out.println("RestoNet Restaurant (" + brand + ") is on-line");        return;    }    private PeerGroupID mkGroupID() throws Exception {        return (PeerGroupID) IDFactory.fromURL(             new URL("urn", "", groupURL));    }}