Toplink in Cluster without Cache Synchronization

Hello,
Iâm trying to setup my J2EE app that uses Toplink for its persistence in a 9iAS cluster. For the first release Iâm not planning to use Toplink Cache synchronization but planning to deploy the app in 9iAS cluster of nodes say A and B. By default all the requests goes to one app server (say A) in the cluster. When the app in node A goes down app in node B starts and accepts all the requests transparently. For this scenario:
1. Do I need to use any Toplink feature/API?
2. What design considerations I need to consider for my app so that I can achieve my short-term goal and the long-term goal of implementing Cache synchronization easily?
Any references/pointers would help me.
Thanks
-Mani

TopLink Cache Coordination (Synchronization) can be enabled at any point during your development. And is not required on a system running in a cluster. No special TopLink API's are required when running in the cluster.
There should be no design decisions made now that would affect the use of Cache Coordination (Synchronization) in the future.
--Gordon

Similar Messages

Toplink 10.1.3 Cache Synchronization

Our application is hosted on a vertical and horizontal cluster.
Server1 has 2 JVMs JVM1 and JVM2
Server2 has 2 JVMs JVM3 and JVM4
I have set cache coordination in a pre login Even Listener, the code to do it is -
RemoteCommandManager rcm =
new RemoteCommandManager((ServerSession)dbSession);
dbSession.setCommandManager(rcm);
dbSession.setShouldPropagateChanges(true);
rcm.getTransportManager().setNamingServiceType(
TransportManager.REGISTRY_NAMING_SERVICE);
rcm.setUrl("rmi://" + hostNamePort);
rcm.getTransportManager().setShouldRemoveConnectionOnError(true);
rcm.initialize();
On each server start up I get the Toplink messages -
RCM service announcement received from Service[TopLinkCommandChannel, 744238172, rmi://xx.xx.xx.xxx:xxxx]
RCM service announcement sent out to cluster
RCM Discovery Manager active
What is happening is that JVM1 and JVM2 send each other updates as do JVM3 and JVM4
But 1 and 2 both do not talk to either 3 or 4, or the other way around, so in other words each servers cluster can talk to each other but cannot talk to the other server.
Can anyone point out what I am doing wrong? Any feedback is highly appreciated.
Thanks

Our application is hosted on a vertical and horizontal cluster.
Server1 has 2 JVMs JVM1 and JVM2
Server2 has 2 JVMs JVM3 and JVM4
I have set cache coordination in a pre login Even Listener, the code to do it is -
RemoteCommandManager rcm =
new RemoteCommandManager((ServerSession)dbSession);
dbSession.setCommandManager(rcm);
dbSession.setShouldPropagateChanges(true);
rcm.getTransportManager().setNamingServiceType(
TransportManager.REGISTRY_NAMING_SERVICE);
rcm.setUrl("rmi://" + hostNamePort);
rcm.getTransportManager().setShouldRemoveConnectionOnError(true);
rcm.initialize();
On each server start up I get the Toplink messages -
RCM service announcement received from Service[TopLinkCommandChannel, 744238172, rmi://xx.xx.xx.xxx:xxxx]
RCM service announcement sent out to cluster
RCM Discovery Manager active
What is happening is that JVM1 and JVM2 send each other updates as do JVM3 and JVM4
But 1 and 2 both do not talk to either 3 or 4, or the other way around, so in other words each servers cluster can talk to each other but cannot talk to the other server.
Can anyone point out what I am doing wrong? Any feedback is highly appreciated.
Thanks

More Control of Cache Synchronization in a Cluster?

If I understand correctly, the cache synchronization manager, by default, sends out a changeSet message to the network for any UOW write commit. Since I have a control on certain objects not using Toplinkâs cache, I actually do not need the cache synchronization manger to broadcast any update on these objects. In other words, I do not want the cache synchronization manger to send out the changeSet message to the network if I only update those objects that are configured to always read from the database. In this way, I may be able to avoid some unnecessary changeSet message propagations.
My question is that whether I have a way, either in sessions.xml or in Java API, to tell the cache synchronization manger not to send out the changeSet message for a given specific UOW write commit (although I still need the data update to be committed to the database).

Many thanks for the reply and glad to see something better is on the way again!
If I choose to set the cache synchronization manager to null, do the UOW write for a given class which is always refreshed from the database, and then reset the cache synchronization manger back to the previous instance, do I need to do the following afterwards:
          // must login/re-login to initialize cache synchronization
          if (session.isConnected()) {
               session.logout();
          session.login();
to ensure the manager be reset properly?
Since the propagation of the changeSet message is triggered by the UOW, can I have more control at the UOW level to turn on/off the cache synchronization manager?
If I understand correctly, in Toplink 10.1.3, I can configure the cache synchronization manger globally at the session level, and also have the option in the same application to set a given number of classes not be cache synchronized in a cluster at the descriptor level to overrule the session global settings. I should not have to choose one over the other. Once these are done in configurations, what is the reason that I still have to choose either to send the changeSet or to invalidate the message?

Toplink cache synchronization between two nodes using tomcat

Hi,
In our appcation we have two nodes. Using websphere we used to synchronize toplink cache between two nodes. Can we do same thing using tomcat.

Yes, TopLink implements cache synchronization using JMS or RMI easily, which are not dependent on the server being used - though it JMS especially does require a JMS provider that is accessible from each node. Cache synchronization is now cache coordination, and is described using JPA properties here:
http://wiki.eclipse.org/EclipseLink/Examples/JPA/CacheCoordination
the Toplink cache synchronization/coordination with JMS | EMBARCADEROS seems to be a good read for cache coordination over JMS, but is more aimed at TopLink's sessions.xml configuration.
Best Regards,
Chris

Exception [TOPLINK-18001] (Cache synchronization)

Hi,
While trying to turn on cache synchronization, getting this exception (see below).
What could be wrong?
Interne Exception: weblogic.jms.common.JMSException: Error deserializing objec
     at oracle.toplink.exceptions.JMSProcessingException.buildDefault(JMSProcessingException.java:20
     at oracle.toplink.remote.jms.TopLinkMessageListener.onMessage(TopLinkMessageListener.java:60
     at weblogic.jms.client.JMSSession.onMessage(JMSSession.java:2596
     at weblogic.jms.client.JMSSession.execute(JMSSession.java:2516
     at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197
     at weblogic.kernel.Kernel.execute(Kernel.java:336
     at weblogic.kernel.Kernel.execute(Kernel.java:360
     at weblogic.kernel.Kernel.execute(Kernel.java:348
     at weblogic.jms.client.JMSSession.pushMessage(JMSSession.java:2392
     at weblogic.jms.client.JMSSession.invoke(JMSSession.java:2919
     at weblogic.jms.dispatcher.Request.wrappedFiniteStateMachine(Request.java:609
     at weblogic.jms.dispatcher.DispatcherImpl.dispatchAsyncInternal(DispatcherImpl.java:128
     at weblogic.jms.dispatcher.DispatcherImpl.dispatchOneWay(DispatcherImpl.java:312
     at weblogic.jms.dispatcher.DispatcherImpl_WLSkel.invoke(Unknown Source
     at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:466
     at weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:409
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:353
     at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:144
     at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:404
     at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:30
     at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197
     at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170
Please help!
THX.

Hi Gordon,
Sorry i don't know what class.
The Excpetion string don't give more information
BEA-040368 14.06.2005 14.36 Uhr IRST Error JMS The following exception has occurred:
Lokaler Exception-Stack:
Exception [TOPLINK-18001] (OracleAS TopLink - 10g (9.0.4.5) (Build 040930)): oracle.toplink.exceptions.JMSProcessingExceptio
Exception-Beschreibung: Fehler bei der Verarbeitung von ankommender JMS-Meldun
Interne Exception: weblogic.jms.common.JMSException: Error deserializing objec
     at oracle.toplink.exceptions.JMSProcessingException.buildDefault(JMSProcessingException.java:20
     at oracle.toplink.remote.jms.TopLinkMessageListener.onMessage(TopLinkMessageListener.java:60
     at weblogic.jms.client.JMSSession.onMessage(JMSSession.java:2596
     at weblogic.jms.client.JMSSession.execute(JMSSession.java:2516
     at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197
     at weblogic.kernel.Kernel.execute(Kernel.java:336
     at weblogic.kernel.Kernel.execute(Kernel.java:360
     at weblogic.kernel.Kernel.execute(Kernel.java:348
     at weblogic.jms.client.JMSSession.pushMessage(JMSSession.java:2392
     at weblogic.jms.client.JMSSession.invoke(JMSSession.java:2919
     at weblogic.jms.dispatcher.Request.wrappedFiniteStateMachine(Request.java:609
     at weblogic.jms.dispatcher.DispatcherImpl.dispatchAsyncInternal(DispatcherImpl.java:128
     at weblogic.jms.dispatcher.DispatcherImpl.dispatchOneWay(DispatcherImpl.java:312
     at weblogic.jms.dispatcher.DispatcherImpl_WLSkel.invoke(Unknown Source
     at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:466
     at weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:409
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:353
     at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:144
     at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:404
     at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:30
     at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197
     at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170
>

Error handling for distributed cache synchronization

Hello,
Can somebody explain to me how the error handling works for the distributed cache synchronization ?
Say I have four nodes of a weblogic cluster and 4 different sessions on each one of those nodes.
On Node A an update happens on object B. This update is going to be propogated to all the other nodes B, C, D. But for some reason the connection between node A and node B is lost.
In the following xml
<cache-synchronization-manager>
<clustering-service>...</clustering-service>
<should-remove-connection-on-error>true</should-remove-connection-on-error>
If I set this to true does this mean that the Toplink will stop sending updates from node A to node B ? I presume all of this is transparent. In order to handle any errors I do not have to write any code to capture this kind of error .
Is that correct ?
Aswin.

This "should-remove-connection-on-error" option mainly applies to RMI or RMI_IIOP cache synchronization. If you use JMS for cache synchronization, then connectivity and error handling is provided by the JMS service.
For RMI, when this is set to true (which is the default) if a communication exception occurs in sending the cache synchronization to a server, that server will be removed and no longer synchronized with. The assumption is that the server has gone down, and when it comes back up it will rejoin the cluster and reconnect to this server and resume synchronization. Since it will have an empty cache when it starts back up, it will not have missed anything.
You do not have to perform any error handling, however if you wish to handle cache synchronization errors you can use a TopLink Session ExceptionHandler. Any cache synchronization errors will be sent to the session's exception handler and allow it to handle the error or be notified of the error. Any errors will also be logged to the TopLink session's log.

Cache Synchronization Exception Handling

I am setting up cache synchronization on WebLogic using JMS. I am looking into writing an exception handler to handle cache synchronization exceptions. The following statement in the documentation caught my attention:
As mentioned above, the TopLink cache does not begin the merge or update process until the database transaction has already been committed. This is quite beneficial in that it avoids letting uncommitted data into the shared cache, but should be recognized where transactional synchronization is considered. In cases where a merge may have failed there is no way to roll back the changes made to the database (although it is questionable whether this would be a good idea in any case). As a consequence, failures during remote merging can leave the cache in an inconsistent state. This makes it important to handle any errors that occur by performing cache normalization actions, such as resetting the cache, or even the server.
Suppose we have two app server instances, A and B. Instance A commits a change and sends the update notification to instance B. The merge fails on instance B with an optimistic lock exception.
- I assume that a CacheSynchronizationException will be thrown. Will it be thrown on instance A, B, or both?
- At this point which cache is inconsistent; A, B, or both?
- The documentation suggests resetting the cache, but this seems a rather severe way of dealing with the problem. Is it feasible / effective to just refresh the objects in the change set of the CacheSynchronizationException?
This is a simple exception handler. On receiving a CacheSynchronizationException it resets the cache and re-throws the exception.
class ToplinkExceptionHandler implements ExceptionHandler{
     public Object handleException(RuntimeException exception) throws DatabaseException{
          if(exception instanceof CacheSynchronizationException){){
               myServerSession.initializeAllIdentityMaps();
               throw exception;
          }else{
               throw exception;
- Is this approach effective?
- Once the cache is reset should the exception be re-thrown or should I consider it handled and swallow it? If I do swallow it what should the method return?
Any advice would be appreciated.

I had to fix a few errors (in our code) before getting it working. Since I have multiple sessions, I had to specify different multicast ports (actually I used a different multicast address itself) for each of the sessions. I was not setting the announcement delay on one of the sesssions and that was why it was announcing immediately upon coming up. Also I had to explicitly set asynchronous to false because it is true by default.
BTW, we are not using CMP (entity beans) rather Java Objects. Our deployment has two Apache/Tomcat machines and two WebLogic machines. The WebLogic servers are in a round-robin cluster. The cache synchronization seems to be working fine for this configuration.
Thanks.
Anand R

Cache Synchronization

I am attempting to setup Toplink Cache synchronization using oracle.toplink.remote.rmi.RMIJNDIClusteringService in a clustered environment
When I launch my server and perform operations I see messages as follows
Announcement sent from 5ff7180-10598c5d31a--7fff192-168-0-4-381481356
I configured my session file as follows
<cache-synchronization-manager>
<clustering-service>
oracle.toplink.remote.rmi.RMIJNDIClusteringService
</clustering-service>
<naming-service-initial-context-factory-name>
com.ibm.websphere.naming.WsnInitialContextFactory
</naming-service-initial-context-factory-name>
<naming-service-url>iiop://localhost:2809</naming-service-url>
</cache-synchronization-manager>
How does Toplink know about the existence of other servers in the cluster ? ( since I do not specify explictly about other members in the cluster in any toplink config file or otherwise)
How can I ensure that all servers in the cluster are getting synchronized.
Details
Toplink version 9.0.4.5
Application Server : WebSphere 5.0.2
Thanks
sk

We have this setup with the following configuration:
<cache-synchronization-manager>
<clustering-service>oracle.toplink.remote.rmi.RMIJNDIClusteringService</clustering-service>
<multicast-port>6018</multicast-port>
<multicast-group-address>226.1.2.3</multicast-group-address>
<is-asynchronous>false</is-asynchronous>
<should-remove-connection-on-error>true</should-remove-connection-on-error>
<naming-service-url>iiop://localhost:1900</naming-service-url>
<naming-service-initial-context-factory>com.ibm.websphere.naming.WsnInitialContextFactory</naming-service-initial-context-factory>
</cache-synchronization-manager>
However, all attempts at locating any packets coming across that port have produced no results. Are we missing something?
The problem we are seeing is that someone is modifying data in one session and another user in another session is not seeing the updates. The problem is intermittent.
Thanks,
Dan

JMS Cache Synchronization - Merge or Database Read?

When an object in one JVM is changed does TopLink' JMS cache synchronization mechanism merge the changes into the other JVMS in a cluster or does it just signal that the object is dirty and the object is re-read from the database?
If the answer is 'merge' does a post merge event get called on the object being merged?
thanks
Steve

In TopLink 10.1.3 both can happen, the changes can be merged or an object can be marked invalid and TopLink will refresh the object as needed. In 9.0.4.X the changes will be merged into the other caches (if an object of correct version exists in that cache).
In the case of a merge postMerge() event will be called.
--Gordon

Cache Synchronization with JMS and a Message Driven Bean (MDB)

If I understand correctly, Toplink ueses the following configuration info to find the target to publish its session messages to a JMS server (having its URL as below) which provides the JNDI service that Toplink needs to look up the topic:
<cache-synchronization-manager>
<clustering-service> oracle.toplink.remote.jms.mdb.JMSPublishingOnlyClusteringService
</clustering-service>
<should-remove-connection-on-error>false</should-remove-connection-on-error>


<jms-topic-connection-factory-name> jms/TopLinkTopicConectionFactory
</jms-topic-connection-factory-name>
<jms-topic-name>jms/TopLinkCacheSynchTopic</jms-topic-name>


<naming-service-url>ormi://localhost:23791</naming-service-url>
<naming-service-initial-context-factory> com.evermind.server.rmi.RMIInitialContextFactory </naming-service-initial-context-factory></cache-synchronization-manager>
The MDB also uses the same JNDI service provided by the JMS server to listen to the topic which is named in the ejb-jar.xml file:
<enterprise-beans>
<message-driven>
<display-name>TopLink clustering MDB</display-name>
<ejb-name>TopLinkClusteringMDB</ejb-name>
<ejb-class>com.mycompany.mdb.ClusteringMDB</ejb-class>
<transaction-type>Container</transaction-type>
<message-driven-destination> <destination-type>javax.jms.Topic</destination-type>
</message-driven-destination>
<env-entry>
<description>TopLink session name</description>
<env-entry-name>tl_session_name_for_mdb</env-entry-name>
<env-entry-type>java.lang.String</env-entry-type>
<env-entry-value>Employee_Session</env-entry-value>
</env-entry>
<resource-ref> <description>description</description>
<res-ref-name>jms/TopLinkTopicConectionFactory</res-ref-name>
<res-type>javax.jms.TopicConnectionFactory</res-type>
<res-auth>Application</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
<resource-env-ref>
<resource-env-ref-name> jms/TopLinkCacheSynchTopic</resource-env-ref-name>
<resource-env-ref-type>javax.jms.Topic</resource-env-ref-type> </resource-env-ref>
</message-driven></enterprise-beans>
To do this, the EJB container that hosts the above MDB needs to be configured to know where the JMS server is by using the above URL same as in the Toplink sessions.xml file.
I am not clear that who provides the JNDI service for the Toplink session name lookup used by the MDB:
// Obtain the Session name configured in the environment variable
String sessionName = (String) myEnv.lookup(TOPLINK_SESSION_NAME);
session = SessionManager.getManager().getSession(sessionName);
so that the MDB can find the currently running Toplink session and communicate with it.
Can anybody help answer my above question and correct my understandings?
Many thanks!

Although TopLink is running in the application serverâs VM, the only notable integration points with the server are for JTA and user-defined data sources. All of the work performed to get a session via SessionManager occurs solely within TopLink. When the call is made to retrieve a session, you arenât getting the âactiveâ session identified by âEmployee_Sessionâ that is registered with the application server, rather a new session is created using the definition that exists for âEmployee_Sessionâ in sessions.xml.
When the call âsession = SessionManager.getManager().getSession(âEmployee_Sessionâ)â is made, the SessionManager simply looks for sessions.xml at the root level of its deployed jars or classpath, then looks for the âEmployee_Sessionâ tag within sessions.xml. If a session exists in the file with that name then a TopLink session object is created and returned.
Note that setting an environment entry as mentioned above simply allows for the session name to be declared dynamically. The call to âmyEnv.lookup(âtl_session_name_for_mdbâ)â simply asks the beanâs environment for the <env-entry-value> that matches the <env-entry-name>. That string is then used in SessionManager (no different than a hard coded value would be) to identify the session in sessions.xml that is to be loaded.
I hope this makes sense.

10.1.3 JMS Cache Synchronization on OC4J

Hi,
We're using stand-alone OC4j 10.1.3.0 along with TopLink 10.1.3.0 (packaged with OC4j). In enabling JMS cache synchronization, I get the following error message:
Exception [TOPLINK-12000] (Oracle TopLink - 10g Release 3 (10.1.3.0.0) (Build 060118)): oracle.toplink.exceptions.CommunicationException
Exception Description: Error Sending connection service to jms/Topic/ToplinkCacheSync.
Internal Exception: javax.jms.JMSException: TopicSubscriber[Oc4jJMS.Consumer.arkansas.6e2ec2b0:1117159d1ca:-7fff.65,Topic[ToplinkCacheSync],null,null,false]: cannot invoke method "setMessageListener" within the J2EE container.
at oracle.toplink.exceptions.CommunicationException.errorSendingConnectionService(CommunicationException.java:40)
at oracle.toplink.remote.CacheSynchronizationManager.addRemoteConnection(CacheSynchronizationManager.java:175)
at oracle.toplink.remote.jms.JMSClusteringService.retreiveRemoteSessions(JMSClusteringService.java:198)
at oracle.toplink.remote.jms.JMSClusteringService.run(JMSClusteringService.java:175)
Caused by: javax.jms.JMSException: TopicSubscriber[Oc4jJMS.Consumer.arkansas.6e2ec2b0:1117159d1ca:-7fff.65,Topic[ToplinkCacheSync],null,null,false]: cannot invoke method "setMessageListener" within the J2EE container.
at com.evermind.server.jms.JMSUtils.make(JMSUtils.java:1034)
at com.evermind.server.jms.JMSUtils.toJMSException(JMSUtils.java:1114)
at com.evermind.server.jms.JMSUtils.toJMSException(JMSUtils.java:1085)
at com.evermind.server.jms.JMSUtils.assertNotContainer(JMSUtils.java:1500)
at com.evermind.server.jms.EvermindMessageConsumer.setMessageListener(EvermindMessageConsumer.java:217)
at oracle.toplink.remote.jms.JMSClusteringService.connectBackToRemote(JMSClusteringService.java:53)
at oracle.toplink.remote.CacheSynchronizationManager.addRemoteConnection(CacheSynchronizationManager.java:168)
... 2 more
It is, therefore, my assumption that Toplink is using JMS 1.0.2b while OC4J is using JMS 1.1. Who can:
1) Verify or debunk my assumption?
2) Point me to a work-around?
Perhaps my config is incorrect? Here's a sessions.xml snippet, in case it helps:
<cache-synchronization-manager>
<clustering-service xsi:type="jms-clustering">
<naming-service-url>ormi://localhost:23791/ems</naming-service-url>
<jndi-user-name>oc4jadmin</jndi-user-name>
<jndi-password>oc4j</jndi-password>
<naming-service-initial-context-factory-name>com.evermind.server.rmi.RMIInitialContextFactory</naming-service-initial-context-factory-name>
<jms-topic-connection-factory-name>jms/Topic/ToplinkCacheSyncConnectionFactory</jms-topic-connection-factory-name>
<jms-topic-name>jms/Topic/ToplinkCacheSync</jms-topic-name>
</clustering-service>
<remove-connection-on-error>false</remove-connection-on-error>
</cache-synchronization-manager>
Many thanks in advance,
--Todd

Thank you very much for your contribution! Yes, indeed, that was my main issue. A sessions.xml section that looks like the following (instead of the <cache-synchronization-manager> section above) does fix the problem:
<remote-command>
<commands>
<cache-sync>true</cache-sync>
</commands>
<transport xsi:type="jms-topic-transport">
<topic-host-url>ormi://localhost:23791/ems</topic-host-url>
<topic-connection-factory-name>jms/Topic/ToplinkCacheSyncConnectionFactory</topic-connection-factory-name>
<topic-name>jms/Topic/ToplinkCacheSync</topic-name>
<jndi-naming-service>
<user-name>oc4jadmin</user-name>
<password>oc4j</password>
<initial-context-factory-name>com.evermind.server.rmi.RMIInitialContextFactory</initial-context-factory-name>
</jndi-naming-service>
</transport>
</remote-command>
Thanks again,
--Todd

10.1.3 cache synchronization using custom RMI code

I am trying to port our custom RMI synchronization code (overriding RMIClusteringService) from 9.0.4 to 10.1.3.
It works by sending an update message to the remote cache whenever an object gets changed on the local cache as follows:
2006.05.15 11:28:38.117--ServerSession(1102039280)--Thread(Thread[RMI TCP Connection(926)-19.39.48.136,5,RMI Runtime])--Received updates from Remote Server
This message then results in a trip to the DB to get the object updates.
Per 10g documentatation, the changed notification should contain the changed attributes (change set) and this should not result in a DB trip for the remote cache. I am not seeing this behavior.
This is probably because I was using the old (9.0.4) sessions file with our custom cache synchronization manager, which overrides toplink cache sync settings, as shown below:
<cache-synchronization-manager>
<clustering-service>
oracle.toplink.remote.rmi.polling.RMIPollingClusteringService
</clustering-service>
<naming-service-url>localhost:1099</naming-service-url>
</cache-synchronization-manager>
<event-listener-class>
oracle.toplink.remote.rmi.polling.RMIPollingClusteringServiceSessionEventAdaptor</event-listener-class>
With 10.1.3 RMIClusteringService is deprecated and replaced by RMITransportManager. A whole bunch of other classes has been added. Has anyone migrated or written RMI custom cache sync code to use RMITransportManager? If so, can they share their experiences and/or send their code samples? Any other thoughts will be appreciated too.
thanks,
Prabodh.

I am trying to port our custom RMI synchronization code (overriding RMIClusteringService) from 9.0.4 to 10.1.3.
It works by sending an update message to the remote cache whenever an object gets changed on the local cache as follows:
2006.05.15 11:28:38.117--ServerSession(1102039280)--Thread(Thread[RMI TCP Connection(926)-19.39.48.136,5,RMI Runtime])--Received updates from Remote Server
This message then results in a trip to the DB to get the object updates.
Per 10g documentatation, the changed notification should contain the changed attributes (change set) and this should not result in a DB trip for the remote cache. I am not seeing this behavior.
This is probably because I was using the old (9.0.4) sessions file with our custom cache synchronization manager, which overrides toplink cache sync settings, as shown below:
<cache-synchronization-manager>
<clustering-service>
oracle.toplink.remote.rmi.polling.RMIPollingClusteringService
</clustering-service>
<naming-service-url>localhost:1099</naming-service-url>
</cache-synchronization-manager>
<event-listener-class>
oracle.toplink.remote.rmi.polling.RMIPollingClusteringServiceSessionEventAdaptor</event-listener-class>
With 10.1.3 RMIClusteringService is deprecated and replaced by RMITransportManager. A whole bunch of other classes has been added. Has anyone migrated or written RMI custom cache sync code to use RMITransportManager? If so, can they share their experiences and/or send their code samples? Any other thoughts will be appreciated too.
thanks,
Prabodh.

Distributed Cache Synchronization

I'm trying to implement distributed cache synchronization via RMI but I find the documentation to be very limited on how to do this. I'm doing exactly what the documentation says and I end up with a CommunicationException when trying to connect to the pre-existing session. The toplink docs are not very descriptive about the cause or meaning of CommunicationException.
Also, this is in toplink 3.6 which I know is old, but comparing it with the new oracle versions the requirements for DCS are almost identical.
Here is the code I'm trying to use:
          RMIRemoteSessionController controller = (RMIRemoteSessionController)Naming.lookup(registryName);
          RemoteConnection connection = new RMIConnection(controller);
          CacheSynchronizationManager syncMgr = new CacheSynchronizationManager();
          serverSession.setCacheSynchronizationManager(syncMgr);
          serverSession.getCacheSynchronizationManager().addRemoteConnection(connection);
Here is the stack trace I'm seeing:
18:53:01,146 DEBUG OEDataEntry - OEDataEntry - - EXCEPTION [TOPLINK-0] (3.6.2 JDK1.2): TOPLink.Public.Remote.CommunicationException
18:53:01,146 DEBUG OEDataEntry - OEDataEntry - - EXCEPTION DESCRIPTION: Error Sending connection service to
18:53:01,156 DEBUG OEDataEntry - OEDataEntry - - INTERNAL EXCEPTION: java.lang.ClassCastException
18:53:01,166 DEBUG OEDataEntry - OEDataEntry - -      at TOPLink.Public.Remote.CacheSynchronizationManager.addRemoteConnectionForSynchronization(CacheSynchronizationManager.java:84)
18:53:01,166 DEBUG OEDataEntry - OEDataEntry - -      at TOPLink.Public.Remote.CacheSynchronizationManager.addRemoteConnection(CacheSynchronizationManager.java:68)

Also, if someone could provide me with a complete example of how to implement distributed cache synchronization via RMI that would be helpful too, the docs are very sparse on this.
Basically what I'm trying to do is this: I have a web application that uses toplink to connect to a database. I have a separate application that also uses toplink to connecto the database that runs outside the application. The external app can update tables that the web application uses, I would like the web application to have it's cache updated when the external app changes something in those tables. It is my understanding that this is what distributed cache synchronization is for. How do I use it?

Deployig to a Cluster without losing session.

Hi,
          We have a cluster setup with 4 servers. We use HttpSession and
          StatefulSessionBeans in the cluster with in-memory replication. Is it
          possible to redeploy the application to a cluster without losing
          session ?.
          Thanks,
          -Senthil.


We have a cluster setup with 4 servers. We use HttpSession and          > StatefulSessionBeans in the cluster with in-memory replication. Is it
          > possible to redeploy the application to a cluster without losing
          > session ?.
          Not with WebLogic session replication. The session replication is "lazy"
          (only when something happens) so the best approach is to make sure there are
          no imcompatibilities and then cycle the cluster one server at a time, maybe
          one server every hour (or whatever your session timeout is).
          Peace,
          Cameron Purdy
          Tangosol, Inc.
          http://www.tangosol.com/coherence.jsp
          Tangosol Coherence: Clustered Replicated Cache for Weblogic
          "Senthil" <[email protected]> wrote in message
          news:[email protected]..
          > Hi,
          >
          >
          > Thanks,
          > -Senthil.

JMS Cache Synchronization Manager

Hi all,
I am trying to implement distributed cache synchronization in TopLink using JMS.
On http://download-west.oracle.com/docs/cd/A97688_12/toplink.903/b10064/enterpri.htm#1022254 , there is an example given which has a snippet of the sessions.xml file.
The example snippet shows a tag <naming-service-initial-context-factory> under the <cache-synchronization-manager> tag. But on the DTD given on http://download-west.oracle.com/docs/cd/A97688_12/toplink.903/b10064/a-sessio.htm#634251 , I cant find an element <naming-service-initial-context-factory>. Please let me know which one is wrong - the DTD or the example?
Also, I tried to use JMS for distributed cache synchronization. My JMS Server is running on a seperate VM and I have configured info about it in the sessions.xml file. But TopLink is complaining that it cannot find the top and connection factory. Yet, I am able to look them up from a standalone program.
Does anyone have any experience setting this up? Any examples?
Thanks,
Binil

Hi Doug,
Thanks for the clarifications! :)
I am not able to get the JMS Cache Synchronization work still :( I am new to JMS & Toplink - so I will try to explain what I am doing and please let me know if there is something I am doing wrong.
I have an EJB application which is a Stateless Session bean which has two methods : one to fetch an entity and another to update an entity. Also, I have a weblogic domain in which I have three managed servers - appServerOne, appServerTwo and jmsServer. On appServerOne and appServerTwo I have deployed the above mentioined application. On jmsServer, I have configured my ConnectionFactory and Topic and the JNDI names of those are provided to the EJB application.
With this setup, I run two client programs. I will list the steps below:
1. Client1 fetches an entity whereby it is loaded to the TopLink cache. The DB logs show that a SELECT query is issued to the DB.
2. Client2 fetches the same entity whereby it is loaded to the cache; again a SELECT query is issued.
3. Client1 updates that entity using UOW; the logs dont show a DB UPDATE statement though. But the updates are indeed made to the DB when I check them.
4. Client1 fetches the entity again; the updates are visible and the JDBC logs show that a trip to the DB is not done.
5. After waiting for sometime Client1 fetches the same entity again and I get the stale data! :(
I have enabled logging, so I am hoping that TopLink will log a message when a JMS notification is posted. Also, I have made the cache synchronization synchronous, so that the transaction shouldnt commit before the notification being send.
I tried making the stateless session bean stateful and it still didnt work. Is there anything I need to do.
Cheerio,
Binil

Toplink in Cluster without Cache Synchronization

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