I would recommend using XA datasources if you plan to have multiple datasources participating in the same transaction.

If you absolutely need to keep local datasources then you need to access each one from a separate transaction.

If you can't do this then you can enable multiple local datasources in the same JBossTS transaction, even though this is not recommended (don't be fooled you have no atomicity guarantees with this approach).

You would have to enable

<property name="com.arjuna.ats.jta.allowMultipleLastResources" value="true"/>

Read further info about this here.

Excellent, thanks for the response.

I have a secondary datasource that is used very rarely, so I don't mind handling the transactions for it by hand. I have no idea how to do that though. the following does not work:

EntityManager em = (EntityManager)Component.getInstance("secondEntityManager",true);
em.getTransaction().begin();
Object result = em.createNativeQuery( "SELECT blah blah").getSingleResult();
em.getTransaction().commit();

I get

java.lang.IllegalStateException: JTA EntityManager cannot access a transactions
	at org.hibernate.ejb.AbstractEntityManagerImpl.getTransaction(AbstractEntityManagerImpl.java:316)
	at org.jboss.seam.persistence.EntityManagerProxy.getTransaction(EntityManagerProxy.java:110)
	at com.trendrr.servlet.api.admin.TorrentSearchStats.process(TorrentSearchStats.java:25)

...

Obviously I can't use the transaction from Transaction.instance(), so how can I create a new useable transaction?

any more help?

-Dustin

Thx for this hint!

Well I must still be missing something. I've tried this and other techniques, but it still seems to try to bind all the entities to every datasource. The entities are all annotated with

@PersistenceContext(unitName="MainDatasource")

But I still get

[ServiceController] Problem starting service persistence.units:ear=myproject-ear.ear,unitName=OtherDatasource
javax.persistence.PersistenceException: org.hibernate.HibernateException: Missing table: MainDatasourceTable

Any other hints? What else am I missing?

I think thats a different problem. Please post a detailed usecase in a new post.

I would recommend using XA datasources if you plan to have multiple datasources participating in the same transaction.

Is it still true if one of the datasources is read-only?

If you absolutely need to keep local datasources then you need to access each one from a separate transaction.

Correct me if I'm wrong, but you cannot suspend or create a new transaction if you're using Seam POJOs:

/**
 * Transaction propagation strategies for Seam JavaBean 
 * components. Note that unlike EJB3 components, there 
 * are no strategies for suspending transactions.
 * 
 * @author Gavin King
 *
 */
public enum TransactionPropagationType
{
   REQUIRED,
   MANDATORY, 
   SUPPORTS,
   NEVER;