endpointrouter.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

        boolean found = false;
        if (qReqAddr.equals(localPeerAddr)) {
            found = true;
        } else {
            if (group.isRendezvous()) {

                if (isLocalRoute(qReqAddr)) {
                    found = true;
                } else {
                    route = getRoute(qReqAddr);
                    if (route != null) {
                        found = true;
                    }
                }
            }
        }

        if (!found) {
            if (!group.isRendezvous()) {
                throw new DiscardQueryException();
            }
	    throw new NoResponseException();
        }

        try {
            // Build the answer
            doc = (StructuredTextDocument)
            StructuredDocumentFactory.newStructuredDocument(
            new MimeMediaType( "text/xml" ), "jxta:EndpointRouter");

            Element e = null;
            e = doc.createElement(VersionTag, Integer.toString(currentVersion));
            doc.appendChild(e);
            e = doc.createElement(TypeTag, RouteResponse);
            doc.appendChild(e);
            e = doc.createElement(DestPeerIdTag, qReqAddr);
            doc.appendChild(e);
            e = doc.createElement(RoutingPeerIdTag, localPeerAddr);
            doc.appendChild(e);
	    if (route != null) {
		e = doc.createElement(NbOfHopsTag, String.valueOf (route.nbOfHops + 1));
	    } else {
		e = doc.createElement(NbOfHopsTag, String.valueOf (1));
	    }
	    doc.appendChild(e);

            if (localPeerAdv != null) {
                e = doc.createElement(RoutingPeerAdvTag, localPeerAdv);
                doc.appendChild(e);
            }

	    // The first gateway is the local peer
	    e = doc.createElement(GatewayForwardTag, localPeerAddr);
	    doc.appendChild(e);

            if (route != null) {
                Vector gateways = route.gateways;
                String gateway = null;
                if ((gateways != null) && (gateways.size() > 0)) {
                    for (int i = 0; i < gateways.size(); ++i) {
                        try {
                            gateway = (String) gateways.elementAt(i);
                            e = doc.createElement(GatewayForwardTag, gateway);
                            doc.appendChild(e);
                        } catch (Exception e1) {
                            continue;
                        }
                    }
                }
            }

            StringWriter dumped = new StringWriter();
            doc.sendToWriter( dumped );

            ResolverResponse res = new ResolverResponse(routerSName,
							null,
							queryId,
							dumped.toString() );

            return res;

        } catch (Exception ee) {
            if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("processQuery: error while processing query: ", ee);
            throw new IOException();
        }
    }

    // This class is used in order to add routing information
    // to Messengers.
    public class RouterMessenger implements EndpointMessenger {

        protected EndpointMessenger messenger = null;
	protected EndpointAddress  destAddress = null;
	protected EndpointRouter router = null;

        public RouterMessenger(EndpointMessenger m,
                               EndpointAddress destAddress,
                               EndpointService e,
                               EndpointRouter r) {
            if( m == null ) {
                if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug( "null messenger!" );
                throw new IllegalArgumentException( "null messenger!");
	    }

            this.messenger = m;
            this.destAddress = destAddress;
	    this.router = r;
        }

        public void sendMessage(Message message) throws IOException {

            if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("EndpointRouterMessenger.sendMessage starts");


	    InputStream ip = null;
	    EndpointRouterMessage routerMsg = null;

	    MessageElement elem =  message.getElement(EndpointRouterMessage.Name);
            if ((elem != null) && ((ip = elem.getStream())!= null)) {

		try {
		    routerMsg = new EndpointRouterMessage(ip);
		} catch (Exception ez1) {
		    // Can't read the element. Ignore it.
		    routerMsg = null;
		}
	    }

	    if (routerMsg == null) {
		// We need to create one.
		if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug ("Create a new EndpointRouterMessage");
		routerMsg = new EndpointRouterMessage();
		routerMsg.setSrcAddress(router.localPeerAddr);
		routerMsg.setNbOfHops ("1");
		try {
		    Route route = router.getRoute (destAddress.getProtocolName() + "://" +
						   destAddress.getProtocolAddress());

		    if (route != null) {
			if (route.gateways != null) {
			    routerMsg.setForwardGateways (route.gateways);
			}
		    }
		} catch (Exception ez1) {
		    // Not much we can do
		    if (LOG.isEnabledFor(Priority.WARN)) LOG.warn ("Cannot set forward gateways");
		}
	    } else {
		if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug ("Using EndpointRouterMessage");

		// If we want to modify the routing header of forwarded
		// messages, HERE is the best place to do it.

		// Check if the destination within the message is the same
		// as the destination peer of this messenger.
		String inMsgDest = routerMsg.getDestAddress();
		if ((inMsgDest != null) && (!inMsgDest.equals (destAddress.toString()))) {
		    // The destination address is not the same. It is very likely
		    // that the router message embedded within the message is
		    // invalid. Update it.
		    routerMsg.setForwardGateways (null);
		    try {
			Route route = router.getRoute (destAddress.toString());
			if (route != null) {
			    if (route.gateways != null) {
				routerMsg.setForwardGateways (route.gateways);
				int nbOfHops = route.gateways.size() + 1;
				routerMsg.setNbOfHops (String.valueOf (nbOfHops));
			    }
			}
		    } catch (Exception ez1) {
			// Not much we can do
			if (LOG.isEnabledFor(Priority.WARN)) LOG.warn ("Cannot set forward gateways");
		    }
		}


		// If the routerMsg still contains a potentially correct reverse route,
		// check it, and if it is really correct, keep it. Otherwise, try to see
		// if we have a reverse route anyway.

		boolean reverse = false;
		if (routerMsg.getReverseGateways() != null) {
		    reverse = isLocalRoute (routerMsg.getLastHop());
		    if (!reverse) {
			routerMsg.setReverseGateways(null);
		    }
		}


		if (!reverse) {
		    // Fine, this peer does not have a reverse route to the
		    // last hop, but maybe it has a route to the source of the message.
		    if (getRoute (routerMsg.getSrcAddress()) != null) {
			reverse = true;
		    } else {
			reverse = isLocalRoute (routerMsg.getSrcAddress());
		    }
		}

		if (reverse) {
		    if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug ("    setting reverse remote route");
		    // Add this local peer as a hop
		    Vector v = routerMsg.getReverseGateways();
		    if (v == null) {
			v = new Vector(1);
		    }
		    try {
            //PDA requirement 18.02.2002
            // Vector.add -> Vector.insertElementAt
			// v.add(0, localPeerAddr);
			v.insertElementAt(localPeerAddr, 0);
		    } catch (Exception ez1) {
			// Not much can be done here.
			if (LOG.isEnabledFor(Priority.WARN)) LOG.warn ("Cannot insert local peer id in the reverse route");
		    }
		    try {
			routerMsg.setNbOfHops
			    (String.valueOf (Integer.parseInt (routerMsg.getNbOfHops()) + 1));
		    } catch (Exception ez1) {
			// Not much we can do here
			if (LOG.isEnabledFor(Priority.WARN)) LOG.warn ("Got exception while trying to set the nbofHops " + ez1);
			routerMsg.setNbOfHops ("0");
		    }
		    routerMsg.setReverseGateways (v);
		} else {
		    // We really have no reverse route. Sorry.
		    if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug ("     no reverse route");
		    routerMsg.setNbOfHops ("0"); //No reverse route
		    routerMsg.setReverseGateways (null);
		}
            }

	    routerMsg.setDestAddress(destAddress.toString());
	    routerMsg.setLastHop(router.localPeerAddr);

            // Push the router header onto the message.
            // That's all we have to do for now.
            try {
		message.addElement(
		   message.newMessageElement (EndpointRouterMessage.Name,
					      null,
					      routerMsg.getInputStream()));
            } catch (Exception e) {
                if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("Can't push header");
            }

            // give the message to the real messenger
            // NB, may be we SHOULD do getTransportMessenger EVERY TIME
            // so that we can recover from broken routes.
	    if (messenger == null) {
		throw new IOException ();
	    }
            messenger.sendMessage(message);

        }

        public void close() {
        }

    }

    // That's what upper layers call (through the endpoint API) to get
    // a messenger to a peer-id based destination.
    public EndpointMessenger getMessenger(EndpointAddress addr)
        throws IOException {


        // Extract the relevant components from this address.
        String dstPAddr = addr.getProtocolName() + "://"
            + addr.getProtocolAddress();

        // If the dest is the local peer, just loop it back without going
        // through the router.
        if (dstPAddr.equals (localPeerAddr)) {
            if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("getMessenger: return LoopbackMessenger");
            return new LoopbackMessenger (endpoint,
                                          endpoint.newEndpointAddress(localPeerAddr),
                                          addr);
        }

        // Find an appropriate real transport messenger for this
        // address.
        EndpointMessenger m = getTransportMessenger(dstPAddr, false);

        // Build a RouterMessenger around it that will add our header.
        return new RouterMessenger(m, addr, endpoint, this);
    }

    // That's what does the job of actually finding the address and
    // endpoint protocol to use to send the message to its next hop.
    // If the local flag is true. We must not look for a route; just use
    // a local route or fail.
    // NB: we need to get rid of this stupid habit of sometimes returning null
    // and sometimes throwing an exception.
    private EndpointMessenger getTransportMessenger(String dstPAddr,
                                                    boolean local)

        throws IOException {

        // Find a raw transport address for this peer.

        EndpointMessenger messenger = null;
        boolean onceMore = true;

        while (onceMore) {
            onceMore=false;

            Address naddr = null;
            if (local) {
                naddr = (Address) getLocalRoute(dstPAddr);
            } else {
                naddr = (Address) getAddress(dstPAddr);
            }

            if (naddr == null) {
                // A null address has no protocol name. This equivalent to a non-existant
                // protocol, which the endpoint service would respond to by returning null.
                // which we handle below by throwing an exception. So, throw an exception here
                // as well, instead of returning null.
                if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("getTransportMessenger: no address");
                throw new IOException("getTransportMessenger: no address");
            }

            // Clone it. The original is in our tables and must not be
            // messed with.
            naddr = (Address) naddr.clone();

            if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("getMessenger(). " +
                                                            "dest peer= " + dstPAddr +
                                                            "using = " + naddr.toString());

            // Complete this address with the router's service queue name
            naddr.setServiceName (routerSName);
            naddr.setServiceParameter (routerSParam);

            // Find the appropriate raw messenger to use.
            try {
                messenger = endpoint.getMessenger(naddr);
                break;
            } catch(IOException noCheese) {
                // find which local route is broken and purge it.
                brokenRoute(dstPAddr);
            }
        }

        // Some transports may return null rather than throwing. Convert.
        if (messenger == null) {
            if (LOG.isEnabledFor(Priority.INFO)) LOG.info("getMessenger: no messenger to "
                                                          + dstPAddr);
            throw new IOException("getTransportMessenger: no messenger");
        }
        return messenger;