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On Wed, 27 Oct 1999 10:49:00 Murali Krishna Devarakonda wrote:
>Since we have this thread going, I had a related question.
>
>A while back I was discussing issues related to caching data in a Stateful
>session bean that communicates with many Entity beans. For good measure,
>let's say the entity bean(EB) is used by more than one "client"- in addition
>to the Stateful session bean(SSB). In other words(IOW:-), the SSB does not
>know when the EB data is changed without making an explicit method call.
>
>Could JMS help here?
Yes, you are using JMS as the underlying backbone for cache synchronization.
Persistence PowerTier (5.0.3.5) uses TIBCO for that very same purpose. However, the
cache is not held in SSB.
>If the stateful session bean wants to make sure it's cached data doesn't get
>stale, it could just listen for the "data updated" event. The message could
>even contain the new data.
>
>Thus, data consistency is achieved by just one-trip: Entity Bean to Stateful
>Session Bean.
>It's also asynchronous. It's also different from the "usual way" in which
>EJB apps are modeled in the sense that we have an Entity Bean communicating
>with the session bean(albeit indirectly).
>
>The immediately obvious problem is that this would(could?) break the
>one-client/one-Stateful session bean requirement, and hence might(will?)
>throw an exception. And even if it did, is there a way to still achieve what
>I'm thinking here?
Yes, it would break the one-client/one-SSB requirement. You would have to hold the
cache in a mechanism outside of the SSBs which all SSBs access. An intermediary
between the SSBs and the Entity beans. I believe this is somewhat close to the
PowerTier architecture.
>
>Could someone less clueless in the EJB/JMS integration issues please
>enlighten me:~?
>
>Thanks for your input,
>Murali Krishna Devarakonda
>e: [EMAIL PROTECTED]
>
Perry Hoekstra
Consultant
Talent Software Services
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