Hi Pablito, I know this isn't exactly what you asked for but if you're using the same database instance and the same PersistenceUnit then it might be easier to use a L2 DataCache [1].
The L2 cache can be shared between all EntityManagers created by a single EntityManagerFactory (or PersistenceUnit). There are also ways to keep the cache synchronized if it's running on different JVMs (the manual is a good starting point for that). [1] http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_caching If you want to be notified to act on the changes (not just to make sure you have the most up to date changes) then you'll need a callback like you suggested. Sadly I'm not aware of such a callback in OpenJPA. Others on the list might know though. Hope this helps and let us know if you have other questions, -mike On Wed, Jun 10, 2009 at 4:26 PM, pablito <[email protected]> wrote: > > Hi: > > I apologise for the newb question, but I'm a still a bit inexperienced when > it comes to the database scene. Basically, I expect to have a number of > servlets using a same database instance (under MySql if that matters). Is > there any way to register a callback against a table or even a particular > record for changes? Basically, I'm looking at a scenario where different > servlets (in Tomcat) are interested in the same table/record and need to > know to re-read the data when it changes. > > I ask here as we will be using OpenJpa, but I can't say I'm aware if > databases generally have this capability. To be clear, I've looked at the > Lifecycle callbacks, but I'm assuming that this isn't meant to cut across > process boundaries. I'm just looking for confirmation either way. > > Many thanks, > Pab > -- > View this message in context: > http://n2.nabble.com/Monitoring-a-database-table-or-individual-record-for-changes--tp3058495p3058495.html > Sent from the OpenJPA Users mailing list archive at Nabble.com. > >
