[hibernate-dev] hibernate-osgi JPA bootstrap & classloader

[Brett Meyer]

> Is that the best way to know when TransactionManagers and DataSources come
> and go too?  Or is there a more specific concept for listening to an "OSGi
> service"?

At least for TransactionManagers, yes, the BundleListener is probably the best approach.  I'm not aware of a more specific way beyond that, but I'm not 100%.  Honestly not sure about the DataSource -- can't remember if most containers automatically expose that or not.

> 
> Also, do the containers generally handle "in-flight" requests in
> regards to TransactionManagers
> and DataSources on activated/deactivated?  I guess this is more a
> curiosity, since I do not see what we could do if the container does not
> manage it.

Really good question, but not sure.  The hope is that a truly OSGi-friendly bundle is "dynamic" enough to gracefully terminate in-progress actions if deactivated.  They're given that opportunity through BundleActivator#stop.  Of course, that's entirely up to the specific impl.  I would expect Karaf container-provided defaults (Geronimo JTA, etc.) to handle that reasonably well for basic cases, but not sure about the real-world edge cases...

Note that I always hoped to make Hibernate fit that bill, but we're *far* from it.  Deactivation would, in all likelihood, be catastrophic.  And no idea about re-activation.