limitedrangegreeter.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

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package net.jxta.impl.rendezvous.limited;

import java.io.IOException;

import java.util.logging.Level;

import net.jxta.logging.Logging;

import java.util.logging.Logger;

import net.jxta.endpoint.EndpointAddress;
import net.jxta.endpoint.EndpointListener;
import net.jxta.endpoint.EndpointService;
import net.jxta.endpoint.Message;

import net.jxta.impl.protocol.LimitedRangeRdvMsg;
import net.jxta.impl.rendezvous.RdvGreeter;
import net.jxta.impl.rendezvous.rpv.PeerViewElement;

/**
 * The limited range rendezvous peer greeter.
 *
 * @see net.jxta.impl.rendezvous.RdvGreeter
 * @see net.jxta.impl.rendezvous.RdvWalk
 * @see net.jxta.impl.rendezvous.RdvWalker
 * @see net.jxta.impl.protocol.LimitedRangeRdvMsg
 */
public class LimitedRangeGreeter implements EndpointListener, RdvGreeter {

    /**
     * Logger
     */
    private static final Logger LOG = Logger.getLogger(LimitedRangeGreeter.class.getName());

    /**
     * The walk we are associated with.
     */
    private final LimitedRangeWalk walk;

    /**
     * XXX It would be nice to avoid making another link to the endpoint.
     */
    private final EndpointService endpoint;

    /**
     * Constructor
     *
     * @param walk The walk we will be associated with.
     */
    public LimitedRangeGreeter(LimitedRangeWalk walk) {
        this.walk = walk;

        this.endpoint = walk.getPeerGroup().getEndpointService();

        if (!endpoint.addIncomingMessageListener(this, walk.getWalkServiceName(), walk.getWalkServiceParam())) {
            throw new IllegalStateException("Could not register endpoint listener for greeter.");
        }

        if (Logging.SHOW_INFO && LOG.isLoggable(Level.INFO)) {
            LOG.info("Listening on " + walk.getWalkServiceName() + "/" + walk.getWalkServiceParam());
        }
    }

    /**
     * {@inheritDoc}
     */
    public synchronized void stop() {
        endpoint.removeIncomingMessageListener(walk.getWalkServiceName(), walk.getWalkServiceParam());
    }

    /**
     * {@inheritDoc}
     * <p/>
     *  Listens on "LR-Greeter"&lt;groupid>/&lt;walkSvc>&lt;walkParam>
     * <p/>
     * Currently, all this method has to do, is to invoke the upper layer.
     */
    public void processIncomingMessage(Message message, EndpointAddress srcAddr, EndpointAddress dstAddr) {

        if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
            LOG.fine("Processing " + message + " from " + srcAddr);
        }

        LimitedRangeRdvMsg rdvMsg = LimitedRangeWalk.getRdvMessage(message);

        // Check and update the Limited Range Rdv Message
        if (null == rdvMsg) {
            // Message is invalid, drop it
            if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
                LOG.warning("Limited Range Greeter received invalid " + message + ". Dropping it.");
            }
            return;
        }

        if (rdvMsg.getTTL() <= 0) {
            if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
                LOG.warning("No TTL remaining for " + message + ". Dropping it.");
            }
            return;
        }

        if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
            LOG.fine("Limited Range Greeter calling listener");
        }

        try {
            walk.getListener().processIncomingMessage(message, srcAddr, dstAddr);
        } catch (Throwable ignored) {
            if (Logging.SHOW_SEVERE && LOG.isLoggable(Level.SEVERE)) {
                LOG.log(Level.SEVERE, "Uncaught Throwable in listener (" + walk.getListener() + ")", ignored);
            }
        }
    }

    /**
     * {@inheritDoc}
     */
    public void replyMessage(Message msg, Message reply) throws IOException {
        LimitedRangeRdvMsg rdvMsg = LimitedRangeWalk.getRdvMessage(msg);

        if (rdvMsg == null) {
            // No RdvMessage. This message was not received by this Greeter.
            throw new IOException("LimitedRangeWalker was not able to send message" + ": not from this greeter");
        }

        PeerViewElement pve = walk.getPeerView().getPeerViewElement(rdvMsg.getSrcPeerID());

        if (null == pve) {
            throw new IOException("LimitedRangeWalker was not able to send message" + ": no pve");
        }

        if (!pve.sendMessage(msg, rdvMsg.getSrcSvcName(), rdvMsg.getSrcSvcParams())) {
            throw new IOException("LimitedRangeWalker was not able to send message" + ": send failed");
        }
    }
}