[JPA Service] EntityManagerFactoryBuilder should get a "getUnitProperties" method

[bjhargrave]

Original bug ID: BZ#136
From: Christoph Läubrich <[email protected]>
Reported version: R4 V4.2

[bjhargrave]

Comment author: Christoph Läubrich <[email protected]>

I refere here to '127.3.4 Custom Configured Entity Manager'.

The specification (indirectly) requires someone using the EntityManagerFactoryBuilder to build custom EntityManagerFactoryS to track the used DatasourceFactory.
Even if it is not written directly the last sentence makes it clear:
"The example does not handle the dynamic dependencies on the associated Data Source Factory service."

But if the Datasource is not provided to the createEntityManagerFactory the "user" has no chance to find out which DatasourceFactory he must track.

There are two options:

• don't care at all (an might hole stale references to an unregistered DatasourceFactory)
• unregister and try to reregister each time a Datasourcefactory services changes

Most implementations throw an exception if the datasource is not avaiable even if this is not specified so you can 'probe' for one by calling createEntityManagerFactory but this choice is, as the two others above very inconvenient.

So I think the best would be to allow access to the Unit-Properties by adding a new getUnitProperties Method to the EntityManagerFactoryBuilder interface.