peerdiscovery.java

We intend to develop a wifi enabled p2p file sharing system on a linux platform using jxta and java.

/***** Part of this code was reused from the example provided by
       JXTA and Sun Microsystems, thus the copyright notice below ****/


/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 */

package edu.uiuc.cs.cs327.linuxwifi.app;

import java.util.Vector.*;
import java.util.Vector;

import edu.uiuc.cs.cs327.linuxwifi.services.*;
import java.io.InputStream;
import java.io.ByteArrayInputStream;
import java.util.Enumeration;

import net.jxta.peergroup.PeerGroup;
import net.jxta.peergroup.PeerGroupFactory;
import net.jxta.exception.PeerGroupException;
import net.jxta.document.Advertisement;
import net.jxta.document.AdvertisementFactory;
import net.jxta.document.MimeMediaType;
import net.jxta.discovery.DiscoveryService;
import net.jxta.discovery.DiscoveryListener;
import net.jxta.discovery.DiscoveryEvent;
import net.jxta.protocol.DiscoveryResponseMsg;
import net.jxta.protocol.PeerAdvertisement;
import net.jxta.protocol.PeerGroupAdvertisement;

public class PeerDiscovery extends Thread implements  DiscoveryListener {

    static public PeerGroup netPeerGroup  = null;
    static PeerGroupAdvertisement groupAdvertisement = null;
    private DiscoveryService discovery;
    PeerAdvertisement peerAdv;
    ServicesApi servicesAPI;
    
    

    Vector availableNodesVector;
	private static final boolean DEBUG = false;   
    boolean isRunning = false;
    
    public PeerDiscovery(ServicesApi servicesAPI)
    {
        this.servicesAPI = servicesAPI;
            availableNodesVector = servicesAPI.getAvailableNodes();
        
        if(DEBUG) System.out.println("In PEER DISCOVERY");
        startJxta();
        if(DEBUG) System.out.println("PeerDiscovery:run()");
        startRunning();
        
    }
    
     public PeerDiscovery()
    {
      //  this.servicesAPI = servicesAPI;
      //     availableNodesVector = servicesAPI.getAvailableNodes();
        
        if(DEBUG) System.out.println("In PEER DISCOVERY");
        startJxta();
        if(DEBUG) System.out.println("PeerDiscovery:run()");
        startRunning();
        
    }
    
    private void  startRunning()
    {
        isRunning=true;
        this.start();
    }
    private void  stopRunning()
    {
        isRunning=false;
    }


    // method to start the JXTA platform
    private void startJxta() {
        try {
            netPeerGroup = PeerGroupFactory.newNetPeerGroup();

            // uncomment the following line if you want to start the app defined
            // the NetPeerGroup Advertisement (by default it's the shell)
            // in our case we want use jxta directly.

           // netPeerGroup.startApp(null);
        }
        catch ( PeerGroupException e) {
            // could not instanciate the group, print the stack and exit
            System.out.println("fatal error : group creation failure");
            e.printStackTrace();
            System.exit(1);
        }

        // obtain our group advertisement
        groupAdvertisement = netPeerGroup.getPeerGroupAdvertisement();

        // Let's get the discovery service we're going to use this
        // one later on
        discovery = netPeerGroup.getDiscoveryService();
    }


    /**
     * This thread loops forever discovering peers
     * every minute, and displaying the results.
     */

    public void run() {
        String peer = null;
        int count=0;
        try {
            // Add ourselves as a DiscoveryListener for DiscoveryResponse events
            discovery.addDiscoveryListener(this);
           // discovery.getRemoteAdvertisements(null,0,null, null, 1, null);
            while (isRunning) {
                // wait a bit before sending a discovery message
                try {
                    Thread.sleep(10 * 1000);
                } catch(Exception e) {}
                if(count <= 10) 
                {
                    System.out.println("Sending a Discovery Message");
                    count++;
                }
                // look for any peer
                discovery.getRemoteAdvertisements(null,DiscoveryService.PEER,null,null,50,null);
            }
        } catch(Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * by implementing DiscoveryListener we must define this method
     * to deal to discovery responses
     */

      public void discoveryEvent(DiscoveryEvent ev) {

        DiscoveryResponseMsg res = ev.getResponse();
        
        // let's get the responding peer's advertisement
        peerAdv =  res.getPeerAdvertisement();
        String name = "unknown";
        
        if (peerAdv != null) {
            // some peers may not respond with their peerAdv
            name = peerAdv.getName();
        }
        if(DEBUG) System.out.println (" [  Got a Discovery Response ["+
                            res.getResponseCount()+ " elements]  from peer : "+ name +"  ]");

               
        boolean notFound = true;
                
        //This Section saves the discovered peers to a vector that is passed to 
        //to ServicesAPI.  It also checks for redundent peer names.  
             
        PeerAdvertisement newAdv=null;
        Enumeration enum = res.getAdvertisements();
                
        if (enum != null ) {              
                        
            while (enum.hasMoreElements()) {
                    
                notFound = true;
                newAdv = (PeerAdvertisement) enum.nextElement();
                if(DEBUG) System.out.println (newAdv.getName());
                    
                for(int i=0; i<availableNodesVector.size(); i++)
                {        
                    if((new String(newAdv.getName().toString())).equals(((NodeObject)availableNodesVector.get(i)).getNodeName()))
                    {
                        if(DEBUG) System.out.println("Already in vector");
                        notFound = false;
                    }
                }
                        
                if(notFound) 
                {
                    if(DEBUG) System.out.println("Wasn't in vector, now putting it in there");
                            
         
                    availableNodesVector.add(new NodeObject(newAdv));
                    servicesAPI.setAvailableNodes(availableNodesVector);
                }
            }


        } // end while
      }//end if

}