dynamic "jta-data-source" prop in persistence.xml - jdbc

Question

I have one application that i install on different servers
each server has different jdbc name
the jdbc name also Defined under the (java) system-prop "jdbc_name" in all servers
i try to change "jta-data-source" dynamically to work with value from system-prop("jdbc_name")
for now
in my case i use
#PersistenceContext(unitName="MyUnit")
private EntityManager em;
persistence.xml:
<persistence-unit name="MyUnit" transaction-type="JTA">
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
<jta-data-source>jdbc/myJdbcName</jta-data-source>
<class>com.myCom.myClass</class>
<properties>
<property name="openjpa.TransactionMode" value="managed"/>
</properties>
</persistence-unit>
im using:
websphere
ejb3
openjpa

Answer 1

As far as i know, there is now way you can do this if you are using container-managed entity-managers.
You will have to resort back to application-managed entity-managers, and in order not to do the manual work, you can integrate this with CDI.
This will involve managing transaction boundaries manually. In order to avoid this kind of manual transaction boundary management, you can use interceptors:
#ApplicationEntityManagerInterceptorBinding
#Interceptor
public class ApplicationEntityManagerInterceptor {
#Inject
#ApplicationEntityManager
private EntityManager em;
#AroundInvoke
public Object intercept(final InvocationContext ic) {
//check if transaction is active, otherwise create a new one
em.createTransaction....
try {
return ic.proceed();
} catch (Exception ex) {
//does the exception require rollback? rollback the transaction here
} finally {
//commit the transaction if necessary.
}
}
}
#Stateless
public class EntityManagerFactoryProducer {
#Produces
#ApplicationEntityManager
public EntityManager entityManager() {
final EntityManagerFactory emf = Persistence.createEntityManager("persistence_name");
return emf.createEntityManager();
}
//you will have to manage this yourself
public void dispose(#Dispose final EntityManager em) {
em.close();
}
}
and then wherever you need it!
#Stateless
#ApplicationEntityManagerInterceptorBinding
public class MyDAO {
#Inject
#ApplicationEntityManager
private EntityManager em;
}