[jboss-user] [JBoss Seam] - Re: TransactionalSeamPhaseListener + Spring @Transactional

[youngm]

Sorry my quotes got alittle messed up. :)
anonymous wrote : Hi,
  | 
  | thank you for your helpful answer. I plan to have a seam independent persistence and service layer using spring + JPA and only use seam in the web layer because of its powerful JSF enhancements.
  | 
  | Do I understand it right:
  | 1. It is possible to use spring manged the local transaction instead of JTA, but I need the RC1 or the SNAPSHOT of Seam. It is not possible with the Beta1. It is important for me, because the application must run both on JBoss and Tomcat. I want to know whether it is necessary to install the embedded-jboss in Tomcat, so that I can use JTA.
  | 
You only need RC1 or snapshot if you wish to use spring managed local transactions that are automatically created and committed by seam in a faces request. Of if you want to use Seam's @Transactional annotation.
anonymous wrote : 
  | 2. Can I use JpaTransactionManager together with RESOURCE_LOCAL tx in persistence.xml. I managed to have a working version with embedded-jboss and JTA. I would like to see it also working with local tx.
  | 

Yes you can use JpaTransactionManager and do transaction management in spring and not have to use the embedded-jboss and jta.

anonymous wrote : 
  | 3. Do I have to use seamEntityManagerFactory,or can I also use Spring LocalContainerEntityManagerFactoryBean? What is the main job of seamEntityManagerFactory?
  | 
If you configure it the way I described above you will be using the Spring LocalContainerEntityManagerFactoryBean.  It will be configured such that spring provides the EntityManagerFactory.  Seam provides it's conversation scoped EntityManager and then SeamManagedEntityManagerFactoryBean takes the Seam conversation scoped EntityManager and exposes it as another EntityManagerFactoryBean that can then be used by JpaTransactionManager to start and stop transactions and used by PersistenceAnnotationBeanPostProcessor to inject the Seam conversation scoped EntityManager into your spring beans.  Which reminds me you will also need to update your PersistenceAnnotationBeanPostProcessor to:

	<bean id="org.springframework.context.annotation.internalPersistenceAnnotationProcessor" class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor">
  | 		<property name="defaultPersistenceUnitName" value="seamEntityManagerFactory"/>
  | 	</bean>
  | 

So that Spring will know that @PersistenceContext should inject the seam entitymanager instance instead of creating a new spring managed one.
anonymous wrote : 
  | 4. The same question applies to persistence context. Does it need to be managed by seam or can it also be managed by Spring?
  | 

Configured the way I told you the PersistenceContext will be managed by Seam.  If you want to take advantage of Seam's Conversation scoped PersistenceContexts then that is the way it will need to be.  This in no way limits your ability to execute code asynchronously or outside of a Seam request though.  Take a look at the spring-seam example.  In there I was actually executing a spring configured timer task on a bean that used a Seam managed persistenceContext.

There is nothing that says you cannot use a Spring managed Entitymanager it just means you won't be able to take advantage of a Conversation scoped EntityManager.

Is there a particular reason why you would want to use a Spring managed EntityManager?


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