Scott Marlow [
http://community.jboss.org/people/smarlow%40redhat.com] modified the
document:
"EJB3/JPA 2.0 support for AS7"
To view the document, visit:
http://community.jboss.org/docs/DOC-16271
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This is about how the AS-7 JPA layer and related concerns. Its a rough draft, mostly
points copied from the JPA 2.0 spec.
1. Container-managed persistence context
1. Transaction scope (JPA 7.6.1)
1. Transaction active invocation
1. Persistence context is created if none already associated with transaction
2. Created persistence context ends when transaction ends
3. An extended persistence context can also be used, which survives when transaction
ends.
2. No transaction invocation
1. Loaded entities are detached at end of method call.
2. Extended scope (JPA 7.6.2)
1. Only supported for stateful session beans.
2. Entity modifications can be made outside of a transaction and are applied on the next
joined transaction (anywhere on the cluster).
3. Extended persistence context (XPC) is created when stateful bean that depends on a XPC
is created.
4. XPC is closed when dependent session bean(s) are closed (via @remove method).
5. Inheritance
1. Stateful beans that create other (local) stateful beans, share the same XPC.
3. Persistence context propagation (JPA 7.6.3)
1. A persistence context will be propagated to multiple entity managers (instances) within
the same local transaction.
2. Remote invocations do not propagate the persistence context.
4. Persistence context propagation requirements for component invocations (JPA 7.6.3.1)
1. no propagation if component is invoked without a JTA transaction or without the JTA
transaction propagating:
1. Transaction scoped entity manager used within the invoked component, will create a new
persistence context.
2. Extended scoped entity manager used within the invoked component, will use the XPC
already bound to the (invoked stateful) bean.
3. If the entity manager is invoked within a JTA transaction, the persistence context is
bound to the JTA transaction.
2. If a component is invoked and the JTA transaction is propagated into the component:
1. If (SFSB) component has a XPC and the transaction already has a different persistence
context associated with it, an EJBException is thrown by the container.
2. If a persistence context is bound to the JTA transaction, it is propagated into any
entity managers used in the invocation.
2. Container requirements review
1. Application-managed persistence context (JPA 7.8.1)
1. Container needs to inject entity manager factory into jndi for application use.
2. Must use PersistenceProvider.createContainerEntityManagerFactory method for 3^rd^ party
support. Internal APIs are fine for our persistence provider.
3. Must use EntityManagerFactory.close method to close the entity manager factory prior to
shutdown (again for 3^rd^ party support).
2. Container-managed persistence context (JPA 7.9.1)
1. For 3^rd^ party support, use EntityManagerFactory.createEntityManager . Consider
using for our persistence provider as well.
2. May pass (PersistenceProperty
(
http://download.oracle.com/javaee/6/api/javax/persistence/PersistenceProp...
PersistenceContext.properties to EntityManagerFactory.createEntityManager(Map).
3. Container EM wrapper could implement some EntityManager.unwrap(Class<T> cls)
calls but should default to underlying EM for unhandled classes.
3. Deployment
1. Extract persistence metadata from persistence.xml
2. Determine the PersistenceProvider classname for each persistence unit (PU). The
default class is currently org.hibernate.ejb.HibernatePersistence.
3. Invoke the PersistenceProvider.createContainerEntityManagerFactory(PersistenceUnitInfo,
Map) to create the EMF that will be used to create all EntityManager's for the PU.
The properties read from the PU are passed as the second parameter.
4. Also pass the “javax.persistence.validation.factory ” property if validation mode is
not set to NONE. The validator factory value appears to be
org.hibernate.validator.engine.ValidatorFactoryImpl. Consult ValidatorFactoryProvider
which is currently used to bootstrap the validator factory in AS6.
5. The PU classes shouldn't be loaded until after the EMF is created.
6. The EntityManagerFactory is closed at undeploy time, which also closes all
EntityManager's opened by each factory.
7. Switchboard changes for PU + PC???
4. Clustering
1. Determine impact on
http://community.jboss.org/docs/DOC-13822
http://community.jboss.org/wiki/OptimizingentityandXPCreplication which may need to be
tweaked for clustering other persistence providers. Judging by the jira status, this
optimization is not in place yet (although Hibernate persistence provider HHH-2762 is
done).
2. Determine impact on
http://community.jboss.org/docs/DOC-9565
http://community.jboss.org/wiki/DevEJB3NewSFSBCache (consider support for other
persistence providers).
3. Other changes?
5. Weld integration (JpaInjectionServices implementation is wired in at boot time).
6. Determine Hibernate release to target integration with.
7. EJB Container interaction
1. TBD
8. Desires1. Maintainable code (a ten minute fix will take ten minutes :)
2. Would like to do a better job of showing what is going on at the EM level (e.g. logging
the EM units of work grouped by transaction).
3. Consider any EM (container) extensions that make it easier to measure performance
(perhaps based on Hibernate statistics). Its always nice to see how long each transaction
took and the units of work within the transaction. It would be nice if we could do this
with any persistence provider (for performance comparison).
4. Deal with the Hibernate persistence provider via the same way as we would interact with
other persistence providers (via PersistenceProvider mentioned above).
5. Peace
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