Multiple DB support

[tkettler]

Hi,

first I have to say that I'm not very experienced with EJB so please correct me if I'm wrong.

In EJB < 3.0 it is possible to assign (in the Deployment Descriptor) a datasource for each Entity Bean. So one could for example have a Bean A from DB A with an association to Bean B from DB B and when accessing the beans, the container trasparently queries/updates the different underlying databases.

If I understand the specification correctly this will not be possible with the JBoss/EJB3 implementation at the moment. Will this be possible in the final version? If not, are there any recommended practices how to work around this?


Thanks in advance
Tim Kettler

[leonell]

Here is the answer (from [e-mail]) to similar question in February.
Original: ( http://www.jboss.org/index.html?module=bb&op=viewtopic&t=60347 )

Currently this is not possible, we only support one database per ejb3 archive.
We do not yet support XML descriptors, as they have not been defined by the EG yet, so you can't use the same ejb3 entity class as two different beans as you could in EJB 2. Once the XML descriptors are working this should not be a problem anymore.

Leonell

[elkner]

And a rejected jira issue ;-)

http://jira.jboss.com/jira/browse/EJBTHREE-105

[bill.burke]

An EntityManager is a set of classes that map to one particular database. YOu can not have relationships that span EntityManagers. Sorry...