Source Code Cross Referenced for RPCLinkProtocol.java in  » Science » Cougaar12_4 » org » cougaar » mts » base » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Science » Cougaar12_4 » org.cougaar.mts.base 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * <copyright>
003:         *  
004:         *  Copyright 1997-2004 BBNT Solutions, LLC
005:         *  under sponsorship of the Defense Advanced Research Projects
006:         *  Agency (DARPA).
007:         * 
008:         *  You can redistribute this software and/or modify it under the
009:         *  terms of the Cougaar Open Source License as published on the
010:         *  Cougaar Open Source Website (www.cougaar.org).
011:         * 
012:         *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
013:         *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
014:         *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
015:         *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
016:         *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
017:         *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
018:         *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
019:         *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
020:         *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
021:         *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
022:         *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
023:         *  
024:         * </copyright>
025:         */
026:
027:        package org.cougaar.mts.base;
028:
029:        import java.net.InetAddress;
030:        import java.net.URI;
031:        import java.util.ArrayList;
032:        import java.util.HashMap;
033:        import java.util.Map;
034:
035:        import org.cougaar.bootstrap.SystemProperties;
036:        import org.cougaar.core.component.ServiceBroker;
037:        import org.cougaar.core.mts.MessageAddress;
038:        import org.cougaar.core.mts.MessageAttributes;
039:        import org.cougaar.core.mts.MessageTransportClient;
040:        import org.cougaar.core.service.IncarnationService;
041:        import org.cougaar.core.service.wp.AddressEntry;
042:        import org.cougaar.core.service.wp.Callback;
043:        import org.cougaar.core.service.wp.Response;
044:        import org.cougaar.core.service.wp.WhitePagesService;
045:        import org.cougaar.mts.std.AttributedMessage;
046:
047:        /**
048:         * This is the parent class of all {@link LinkProtocol}s that use a
049:         * remote-procedure-call (rpc) semantics.  Instantiable extensions
050:         * must provide implementations for a small set of abstract methods,
051:         * covering protocol specifics.
052:         */
053:        abstract public class RPCLinkProtocol extends LinkProtocol {
054:
055:            private URI ref;
056:            private IncarnationService incarnationService;
057:            private WhitePagesService wpService;
058:            private HashMap links;
059:            private Object ipAddrLock = new Object();
060:            private ArrayList clients = new ArrayList();
061:
062:            // Just for testing -- an example of supplying a service from a
063:            // LinkProtocol.
064:
065:            public interface Service extends LinkProtocolService {
066:                // protocol-specific methods would go here.
067:            }
068:
069:            public Object getService(ServiceBroker sb, Object requestor,
070:                    Class serviceClass) {
071:                if (serviceClass == Service.class) {
072:                    return new ServiceProxy();
073:                } else {
074:                    return null;
075:                }
076:            }
077:
078:            public void releaseService(ServiceBroker sb, Object requestor,
079:                    Class serviceClass, Object service) {
080:
081:                if (serviceClass == Service.class) {
082:                    // no-op for this example
083:                }
084:            }
085:
086:            // If LinkProtocols classes want to define this method, eg in
087:            // order to provide a service, they should not in general invoke
088:            // super.load(), since if they do they'll end up clobbering any
089:            // services defined by super classes service.  Instead they should
090:            // use super_load(), defined in LinkProtocol, which runs the
091:            // standard load() method without running any intervening ones.
092:            public void load() {
093:                super _load();
094:                links = new HashMap();
095:
096:                ServiceBroker sb = getServiceBroker();
097:                sb.addService(Service.class, this );
098:
099:                incarnationService = (IncarnationService) sb.getService(this ,
100:                        IncarnationService.class, null);
101:                if (incarnationService == null
102:                        && loggingService.isWarnEnabled())
103:                    loggingService.warn("Couldn't load IncarnationService");
104:
105:                wpService = (WhitePagesService) sb.getService(this ,
106:                        WhitePagesService.class, null);
107:                if (wpService == null && loggingService.isWarnEnabled())
108:                    loggingService.warn("Couldn't load WhitePagesService");
109:            }
110:
111:            // subclass responsibility
112:
113:            /**
114:             * @return an identifier of the protocol that can be used by the
115:             * WP to distinguish them from one another.
116:             */
117:            abstract protected String getProtocolType();
118:
119:            /**
120:             * @return a boolean indicating where or not the protocol uses ssl
121:             */
122:            abstract protected Boolean usesEncryptedSocket();
123:
124:            /**
125:             * @return the cost of transmitting the message over this
126:             * protocol.
127:             */
128:            abstract protected int computeCost(AttributedMessage message);
129:
130:            /**
131:             * Return a protocol-specific {@link DestinationLink} for the
132:             * target address.  The name should not be taken to mean that a
133:             * new link will be created for every call.
134:             */
135:            abstract protected DestinationLink createDestinationLink(
136:                    MessageAddress address);
137:
138:            /**
139:             * Ensure that some abstract form of 'servant' object exists for
140:             * this protocol that will allow other Nodes to send messages to his
141:             * one.
142:             */
143:            abstract protected void findOrMakeNodeServant();
144:
145:            /**
146:             * Releases all resources associated with this link protocol.
147:             * <p>
148:             * 
149:             * This method is invoked when the MTS is unloaded so the garbage
150:             * collector can reclaim all resources that had been allocated.
151:             * 
152:             * Fix for bug 3965:
153:             * http://bugs.cougaar.org/show_bug.cgi?id=3965
154:             */
155:            abstract protected void releaseNodeServant();
156:
157:            /**
158:             * Force the proticol to remake its 'servant', typically because
159:             * the address of the Host on which the Node is running has changed.
160:             * Some protoocol (eg HTTP) can ignore this.
161:             */
162:            abstract protected void remakeNodeServant();
163:
164:            protected void setNodeURI(URI ref) {
165:                this .ref = ref;
166:            }
167:
168:            public boolean addressKnown(MessageAddress address) {
169:                if (loggingService.isErrorEnabled())
170:                    loggingService
171:                            .error("The addressKnown method of RMILinkProtocol is no longer supported");
172:                Link link = (Link) links.get(address);
173:                return link != null && link.remote_ref != null;
174:            }
175:
176:            protected boolean isServantAlive() {
177:                return ref != null;
178:            }
179:
180:            public final void registerClient(MessageTransportClient client) {
181:                synchronized (ipAddrLock) {
182:                    findOrMakeNodeServant();
183:                    if (isServantAlive()) {
184:                        try {
185:                            // Assume node-redirect
186:                            MessageAddress addr = client.getMessageAddress();
187:                            getNameSupport().registerAgentInNameServer(ref,
188:                                    addr, getProtocolType());
189:                        } catch (Exception e) {
190:                            if (loggingService.isErrorEnabled())
191:                                loggingService.error(
192:                                        "Error registering client", e);
193:                        }
194:                    }
195:                    clients.add(client);
196:                }
197:            }
198:
199:            public final void unregisterClient(MessageTransportClient client) {
200:                synchronized (ipAddrLock) {
201:                    try {
202:
203:                        // Assume node-redirect
204:                        MessageAddress addr = client.getMessageAddress();
205:                        getNameSupport().unregisterAgentInNameServer(ref, addr,
206:                                getProtocolType());
207:                        clients.remove(client);
208:
209:                        if (clients.isEmpty()) {
210:                            // Fix for bug 3965:  Release RMI stub on node shutdown.
211:                            releaseNodeServant();
212:                        }
213:
214:                    } catch (Exception e) {
215:                        if (loggingService.isErrorEnabled())
216:                            loggingService.error("Error unregistering client",
217:                                    e);
218:                    }
219:                }
220:            }
221:
222:            public final void reregisterClients() {
223:                synchronized (ipAddrLock) {
224:                    if (ref != null) {
225:                        String protocolType = getProtocolType();
226:                        for (int i = 0; i < clients.size(); i++) {
227:                            MessageTransportClient client = (MessageTransportClient) clients
228:                                    .get(i);
229:                            MessageAddress addr = client.getMessageAddress();
230:                            getNameSupport().registerAgentInNameServer(ref,
231:                                    addr, protocolType);
232:                        }
233:                    }
234:                }
235:            }
236:
237:            // Unregister all current clients (inform the WP); close the RMI
238:            // listener; remake the RMI impl; re-register clients (WP).
239:            public void ipAddressChanged() {
240:                synchronized (ipAddrLock) {
241:                    // update hostname property
242:                    try {
243:                        InetAddress local = InetAddress.getLocalHost();
244:                        String hostaddr = local.getHostAddress();
245:                        SystemProperties.setProperty(
246:                                "java.rmi.server.hostname", hostaddr);
247:                    } catch (java.net.UnknownHostException ex) {
248:                        // log something
249:                        if (loggingService.isWarnEnabled())
250:                            loggingService.warn("Couldn't get localhost: "
251:                                    + ex.getMessage());
252:                    }
253:                    NameSupport ns = getNameSupport();
254:                    String type = getProtocolType();
255:                    MessageTransportClient client;
256:                    for (int i = 0; i < clients.size(); i++) {
257:                        client = (MessageTransportClient) clients.get(i);
258:                        ns.unregisterAgentInNameServer(ref, client
259:                                .getMessageAddress(), type);
260:                    }
261:
262:                    remakeNodeServant();
263:                    for (int i = 0; i < clients.size(); i++) {
264:                        client = (MessageTransportClient) clients.get(i);
265:                        ns.registerAgentInNameServer(ref, client
266:                                .getMessageAddress(), type);
267:                    }
268:                }
269:            }
270:
271:            // Factory methods:
272:
273:            public DestinationLink getDestinationLink(MessageAddress address) {
274:                DestinationLink link = null;
275:                synchronized (links) {
276:                    link = (DestinationLink) links.get(address);
277:                    if (link == null) {
278:                        link = createDestinationLink(address);
279:                        link = (DestinationLink) attachAspects(link,
280:                                DestinationLink.class);
281:                        links.put(address, link);
282:                    }
283:                }
284:
285:                return link;
286:            }
287:
288:            private class WPCallback implements  Callback {
289:                Link link;
290:
291:                WPCallback(Link link) {
292:                    this .link = link;
293:                }
294:
295:                private long extractIncarnation(Map entries) {
296:                    // parse "(.. type=version uri=version:///1234/blah)"
297:                    if (entries == null)
298:                        return 0;
299:
300:                    AddressEntry ae = (AddressEntry) entries.get("version");
301:                    if (ae == null)
302:                        return 0;
303:
304:                    try {
305:                        String path = ae.getURI().getPath();
306:                        int end = path.indexOf('/', 1);
307:                        String incn_str = path.substring(1, end);
308:                        return Long.parseLong(incn_str);
309:                    } catch (Exception e) {
310:                        if (loggingService.isDetailEnabled()) {
311:                            loggingService
312:                                    .detail("ignoring invalid version entry: "
313:                                            + ae);
314:                        }
315:                        return 0;
316:                    }
317:                }
318:
319:                public void execute(Response response) {
320:                    Response.GetAll rg = (Response.GetAll) response;
321:                    Map entries = rg.getAddressEntries();
322:                    AddressEntry entry = null;
323:                    long incn = 0;
324:                    if (entries != null) {
325:                        entry = (AddressEntry) entries.get(getProtocolType());
326:                        incn = extractIncarnation(entries);
327:                    }
328:                    if (loggingService.isDebugEnabled())
329:                        loggingService.debug("Brand spanking new WP callback: "
330:                                + entry + " incarnation = " + incn);
331:                    link.handleWPCallback(entry, incn);
332:                }
333:            }
334:
335:            abstract protected class Link implements  DestinationLink,
336:                    IncarnationService.Callback {
337:
338:                private MessageAddress target;
339:                private boolean lookup_pending = false;
340:                private AddressEntry lookup_result = null;
341:                private Object lookup_lock = new Object();
342:                private long incarnation;
343:                private Callback lookup_cb = new WPCallback(this );
344:                private Object remote_lock = new Object();
345:                private Object remote_ref; // URI, URL etc
346:
347:                protected Link(MessageAddress destination) {
348:                    this .target = destination;
349:                    // subscribe to IncarnationService
350:                    if (incarnationService != null) {
351:                        incarnation = incarnationService.getIncarnation(target);
352:                        incarnationService.subscribe(destination, this );
353:                    }
354:                }
355:
356:                abstract protected Object decodeRemoteRef(URI ref)
357:                        throws Exception;
358:
359:                abstract protected MessageAttributes forwardByProtocol(
360:                        Object remote, AttributedMessage message)
361:                        throws NameLookupException, UnregisteredNameException,
362:                        CommFailureException, MisdeliveredMessageException;
363:
364:                // WP callback
365:                private void handleWPCallback(AddressEntry entry, long incn) {
366:                    synchronized (lookup_lock) {
367:                        lookup_pending = false;
368:                        if (incn > incarnation) {
369:                            // tell the incarnation service
370:                            incarnationService.updateIncarnation(target, incn);
371:                            incarnation = incn;
372:                        } else if (incn == 0) {
373:                            // Reset the incarnation number, for nameserver bootstrap
374:                            // don't tell incarnation service, it will ignore 0;
375:                            incarnation = 0;
376:                        }
377:                        lookup_result = (entry != null && incn == incarnation) ? entry
378:                                : null;
379:                    }
380:                }
381:
382:                protected void decache() {
383:                    synchronized (remote_lock) {
384:                        remote_ref = null;
385:                    }
386:                    synchronized (lookup_lock) {
387:                        if (!lookup_pending)
388:                            lookup_result = null;
389:                    }
390:                }
391:
392:                protected URI getRemoteURI() {
393:                    synchronized (lookup_lock) {
394:                        if (lookup_result != null) {
395:                            return lookup_result.getURI();
396:                        } else if (lookup_pending) {
397:                            return null;
398:                        } else {
399:                            lookup_pending = true;
400:                            wpService.getAll(target.getAddress(), lookup_cb);
401:                            // The results may have arrived as part of
402:                            // registering callback
403:                            if (lookup_result != null) {
404:                                return lookup_result.getURI();
405:                            } else {
406:                                return null;
407:                            }
408:                        }
409:                    }
410:                }
411:
412:                // IncarnationService callback
413:                public void incarnationChanged(MessageAddress addr, long incn) {
414:                    synchronized (lookup_lock) {
415:                        if (incn > incarnation) {
416:                            // newer value -- decache the stub
417:                            incarnation = incn;
418:                            decache();
419:                        } else if (incn == 0) {
420:                            // incarnation number reset for nameserver bootstrap
421:                            if (loggingService.isWarnEnabled())
422:                                loggingService
423:                                        .warn("Incarnation service callback has zero incarnation number for "
424:                                                + addr);
425:                            incarnation = 0;
426:                            decache();
427:                        } else if (incn < incarnation) {
428:                            // out-of-date info
429:                            if (loggingService.isWarnEnabled())
430:                                loggingService
431:                                        .warn("Incarnation service callback has out of date incarnation number "
432:                                                + incn + " for " + addr);
433:                        }
434:                    }
435:                }
436:
437:                // NB: Intentionally not synchronized on remote_lock because a
438:                // network invocation can happen in lookupRMIObject().  Worst
439:                // case scenario: normal return (no exception) but 'remote' has
440:                // been reset to null in the meantime.  The two callers
441:                // (isValid and forwardMessage) deal with this case.
442:                protected void cacheRemote() throws NameLookupException,
443:                        UnregisteredNameException {
444:                    if (remote_ref == null) {
445:                        try {
446:                            URI ref = getRemoteURI();
447:                            remote_ref = decodeRemoteRef(ref);
448:                        } catch (Exception lookup_failure) {
449:                            throw new NameLookupException(lookup_failure);
450:                        }
451:
452:                        if (remote_ref == null)
453:                            throw new UnregisteredNameException(target);
454:
455:                    }
456:                }
457:
458:                public MessageAttributes forwardMessage(
459:                        AttributedMessage message) throws NameLookupException,
460:                        UnregisteredNameException, CommFailureException,
461:                        MisdeliveredMessageException {
462:                    cacheRemote();
463:                    // Ordinarily cacheRemote either throws an Exception or
464:                    // caches a non-null reference.  But with the addition of
465:                    // the IncarnationService callbacks, the reference can now
466:                    // be clobbered subsequently by another thread.  Deal with
467:                    // that here.
468:
469:                    // JAZ remote lock is no longer around the remote call.
470:                    // The look isonly be held long enough to get the reference
471:                    // and "commit to the remote call"
472:                    // Why was it around a remote call an not just the remote ref?
473:                    // Does this have something to do with detecting that the message is intransiant
474:
475:                    Object committedRemoteRef; // URI, URL etc		
476:                    synchronized (remote_lock) {
477:                        committedRemoteRef = remote_ref;
478:                    }
479:                    if (committedRemoteRef == null) {
480:                        Exception cause = new Exception(
481:                                "Inconsistent remote reference cache");
482:                        throw new NameLookupException(cause);
483:                    } else {
484:                        return forwardByProtocol(committedRemoteRef, message);
485:                    }
486:
487:                }
488:
489:                public boolean retryFailedMessage(AttributedMessage message,
490:                        int retryCount) {
491:                    return true;
492:                }
493:
494:                public boolean isValid() {
495:                    try {
496:                        cacheRemote();
497:                        // Ordinarily cacheRemote either throws an Exception
498:                        // or caches a non-null reference.  But with the
499:                        // addition of the IncarnationService callback, the
500:                        // reference can now be clobbered subsequently by
501:                        // another thread.  Deal with that here.
502:                        synchronized (remote_lock) {
503:                            return remote_ref != null;
504:                        }
505:                    } catch (NameLookupException name_ex) {
506:                        return false;
507:                    } catch (UnregisteredNameException unknown_ex) {
508:                        // still waiting?
509:                        return false;
510:                    } catch (Throwable th) {
511:                        loggingService.error("Can't compute RMI cost", th);
512:                        return false;
513:                    }
514:                }
515:
516:                public int cost(AttributedMessage message) {
517:                    synchronized (remote_lock) {
518:                        if (remote_ref == null)
519:                            return Integer.MAX_VALUE;
520:                        else
521:                            return computeCost(message);
522:                    }
523:                }
524:
525:                public MessageAddress getDestination() {
526:                    return target;
527:                }
528:
529:                public Object getRemoteReference() {
530:                    return remote_ref;
531:                }
532:
533:                public void addMessageAttributes(MessageAttributes attrs) {
534:                    attrs.addValue(MessageAttributes.IS_STREAMING_ATTRIBUTE,
535:                            Boolean.TRUE);
536:
537:                    attrs.addValue(
538:                            MessageAttributes.ENCRYPTED_SOCKET_ATTRIBUTE,
539:                            usesEncryptedSocket());
540:
541:                }
542:
543:            }
544:
545:        }
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