if I understand correctly, you have multiple tomcat instances.

1. each system has the same webapp
2. each system caches data locally
3. you want to update the application context
4. you want the cluster to replicate the application context
5. you didn't design it and have to live with it

replicating the app context ideally should happen in a push manner if being "in sync" is of any importance. I'm not convinced enhancing the exist session replication is the best way to handle this because the data could be huge. Even if the documentation were to state, do not put large amounts of data in the application context, people will still do it and blame tomcat. the worse part is caching app context data means an additional burden on the session replication mechanism, which is dangerous.

It might be better off for your app context to register for updates with a JMS server. this way, changes can be pushed to the tomcat instances. Or something equivalent to a push mechanism.

peter lin



Rick Szeto <rick.szeto@(protected):
As I was not involved in the design decision, I can not say whether or
not that it is a good call or not. But the reason that we need
application context replication is that the entire site serves up
relatively static data(infrequent updates) to all of it the users. They
did not feel that hitting the DB every time a page is accessed was
efficient.

Rick


---------------------------------
Do you Yahoo!?
Yahoo! Hotjobs: Enter the "Signing Bonus" Sweepstakes