Hi Vamsi,

If the users are updating the same database and objects, then you will need
to deal with clustering

Lets say you have Machine 1 and Machine 2

1. Bob on Machine 1 retrieves object A which is stored in the cache.
2. Carol on Machine 2 retrieves Object A, and updates it
3. Bob on Machine 1 re-retrieves object, which comes from the cache. Bob
will not see Carols changes.

If you have two VM's updating the same objects, you need to implement some
kind of cluster aware cache, which would flush Machine 1's copy of Object A
when Machine 2 updates it.

I know the theory - I just haven't personally implemented any cluster-aware
caching yet. OJB supports pluggable caches. according to
http://db.apache.org/ojb/docu/guides/objectcache.html#ObjectCacheOSCacheImpl
there is a OSCache implementation - but in what OJB version it was
implemented, and what JVM it is compatible with, I am not sure. I do not
believe it would be difficult create wrapper around any distributed cache
for OJB.

Cheers,

Charles

-----Original Message-----
From: Vamsi Atluri [mailto:[EMAIL PROTECTED]
Sent: 17 May 2006 19:53
To: OJB Users List
Subject: Clustering for OJB


Hi all,
 
I am getting some errors when I move from a non-clustered environment in our
testbed to a clustered environment in QA. I have read the document about
setting up OJBs in a clustered environment, however, in our cluster, there
is no session sharing between various nodes in the cluster. And once a user
is assigned a session on a particular server in the cluster, he always goes
to the same machine till his session is terminated. So I was under the
impression that I do not have to do OJB clustering. Am I correct or wrong?
Also, is OSCache supported for jdk1.3.1 and OJB 1.0.1? As always, I really
appreciate any help.
 
Regards,
-Vamsi

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