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<a href="http://community.jboss.org/index.jspa" style="text-decoration: none; color: #E1E1E1">JBoss Community</a></h1>
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EJB3/JPA 2.0 support for AS7
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modified by <a href="http://community.jboss.org/people/smarlow%40redhat.com">Scott Marlow</a> in <i>JBoss AS7 Development</i> - <a href="http://community.jboss.org/docs/DOC-16271">View the full document</a>
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<div class="jive-rendered-content"><p style="margin-bottom: 0in;">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.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><ol><li><p style="margin-bottom: 0in;">Container-managed persistence context</p><ol><li><p style="margin-bottom: 0in;">Transaction scope (JPA 7.6.1)</p><ol><li><p style="margin-bottom: 0in;">Transaction active invocation</p><ol><li><p style="margin-bottom: 0in;">Persistence context is created if none already associated with transaction</p></li><li><p style="margin-bottom: 0in;">Created persistence context ends when transaction ends</p></li><li><p style="margin-bottom: 0in;">An extended persistence context can also be used, which survives when transaction ends.</p></li></ol> </li><li><p style="margin-bottom: 0in;">No transaction invocation</p><ol><li><p style="margin-bottom: 0in;">Loaded entities are detached at end of method call.</p></li></ol> </li></ol> </li><li><p style="margin-bottom: 0in;">Extended scope (JPA 7.6.2)</p><ol><li><p style="margin-bottom: 0in;">Only supported for stateful session beans.</p></li><li><p style="margin-bottom: 0in;">Entity modifications can be made outside of a transaction and are applied on the next joined transaction (anywhere on the cluster).</p></li><li><p style="margin-bottom: 0in;">Extended persistence context (XPC) is created when stateful bean that depends on a XPC is created.</p></li><li><p style="margin-bottom: 0in;">XPC is closed when dependent session bean(s) are closed (via @remove method).</p></li><li><p style="margin-bottom: 0in;">Inheritance</p><ol><li><p style="margin-bottom: 0in;">Stateful beans that create other (local) stateful beans, share the same XPC.</p></li></ol> </li></ol> </li><li><p style="margin-bottom: 0in;">Persistence context propagation (JPA 7.6.3)</p><ol><li><p style="margin-bottom: 0in;">A persistence context will be propagated to multiple entity managers (instances) within the same local transaction.</p></li><li><p style="margin-bottom: 0in;">Remote invocations do not  propagate the persistence context.</p></li></ol> </li><li><p style="margin-bottom: 0in;">Persistence context propagation requirements for component invocations (JPA 7.6.3.1)</p><ol><li><p style="margin-bottom: 0in;">no propagation if component is invoked without a JTA transaction or without the JTA transaction propagating:</p><ol><li><p style="margin-bottom: 0in;">Transaction scoped entity manager used within the invoked component, will create a new persistence context.</p></li><li><p style="margin-bottom: 0in;">Extended scoped entity manager used within the invoked component, will use the XPC already bound to the (invoked stateful) bean.</p></li><li><p style="margin-bottom: 0in;">If the entity manager is invoked within a JTA transaction, the persistence context is bound to the JTA transaction.</p></li></ol> </li><li><p style="margin-bottom: 0in;">If a component is invoked and the JTA transaction is propagated into the component:</p><ol><li><p style="margin-bottom: 0in;">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.</p></li><li><p style="margin-bottom: 0in;">If a persistence context is bound to the JTA transaction, it is propagated into any entity managers used in the invocation.</p></li></ol> </li></ol> </li></ol> </li><li><p style="margin-bottom: 0in;">Container requirements review</p><ol><li><p style="margin-bottom: 0in;">Application-managed persistence context (JPA 7.8.1)</p><ol><li><p style="margin-bottom: 0in;">Container needs to inject entity manager factory into jndi for application use.</p></li><li><p style="margin-bottom: 0in;">Must use PersistenceProvider.createContainerEntityManagerFactory method for 3<sup>rd</sup> party support.  Internal APIs are fine for our persistence provider.</p></li><li><p style="margin-bottom: 0in;">Must use EntityManagerFactory.close method to close the entity manager factory prior to shutdown (again for 3<sup>rd</sup> party support).</p></li></ol> </li><li><p style="margin-bottom: 0in;">Container-managed persistence context (JPA 7.9.1)</p><ol><li><p style="margin-bottom: 0in;">For 3<sup>rd</sup> party support, use EntityManagerFactory.createEntityManager .  Consider using  for our persistence provider as well.</p></li><li><p style="margin-bottom: 0in;">May pass (<code class="western"><span style="font-size: 10pt;"><a class="jive-link-external-small" href="http://download.oracle.com/javaee/6/api/javax/persistence/PersistenceProperty.html">PersistenceProperty</a>[]</span></code>) PersistenceContext.properties to EntityManagerFactory.createEntityManager(Map).</p></li><li><p style="margin-bottom: 0in;">Container EM wrapper could implement some EntityManager.unwrap(Class<T> cls) calls but should default to underlying EM for unhandled classes.</p></li></ol> </li></ol> </li><li><p style="margin-bottom: 0in;">Deployment</p><ol><li><p style="margin-bottom: 0in;">Extract persistence metadata from persistence.xml</p></li><li><p style="margin-bottom: 0in;">Determine the PersistenceProvider classname for each persistence unit (PU).  The default class is currently org.hibernate.ejb.HibernatePersistence.</p></li><li><p style="margin-bottom: 0in;">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.</p></li><li><p style="margin-bottom: 0in;">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.</p></li><li><p style="margin-bottom: 0in;">The PU classes shouldn't be loaded until after the EMF is created.</p></li><li><p style="margin-bottom: 0in;">The EntityManagerFactory is closed at undeploy time, which also closes all EntityManager's opened by each factory.</p></li><li><p style="margin-bottom: 0in;">Switchboard changes for PU + PC???</p></li></ol> </li><li><p style="margin-bottom: 0in;">Clustering</p><ol><li><p style="margin-bottom: 0in;">Determine impact on <a class="jive-link-wiki-small" href="http://community.jboss.org/docs/DOC-13822">http://community.jboss.org/wiki/OptimizingentityandXPCreplication</a> 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).</p></li><li><p style="margin-bottom: 0in;">Determine impact on <a class="jive-link-wiki-small" href="http://community.jboss.org/docs/DOC-9565">http://community.jboss.org/wiki/DevEJB3NewSFSBCache</a> (consider support for other persistence providers).</p></li><li>Other changes?</li></ol> </li><li><p style="margin-bottom: 0in;">Weld integration  (JpaInjectionServices implementation is wired in at boot time).</p></li><li>Determine Hibernate release to target integration with.</li><li><p style="margin-bottom: 0in;">EJB Container interaction</p><ol><li>TBD</li></ol></li><li>Desires<ol><li>Maintainable code (a ten minute fix will take ten minutes <span> :) </span></li><li>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).  </li></ol></li></ol></div>
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<p style="margin: 0;">Comment by <a href="http://community.jboss.org/docs/DOC-16271">going to Community</a></p>
<p style="margin: 0;">Create a new document in JBoss AS7 Development at <a href="http://community.jboss.org/choose-container!input.jspa?contentType=102&containerType=14&container=2225">Community</a></p>
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