[wildfly-dev] duel between JPA use of ClassFileTransformer and CDI implicit/explicit Bean Manager (why can't we just get along)...

[Jason Greene]

Right but my point is if the entities aren't instantiated, there is nothing for the listener to listen for, and it can be delayed up until that point in the deployment process. 

It seems that the only hard ordering, is that the bean manager be created on top of PersistenceUnitInfo.getClassLoader().

On Jun 10, 2013, at 4:41 PM, Steve Ebersole <steve at hibernate.org> wrote:

> We are talking about entity listeners, not entities.  Entities can be annotated with callback methods as well, but those are not supported (by spec) for CDI injection.
> 
> BTW, for those maybe not familiar... The relevant sections in the JPA spec are:
> 
> 9.1 Java EE Deployment.  In this section, it discusses the expectations of the container.  In the part that discusses the call to createContainerEntityManagerFactory (aka, bootstrapping an EntityManagerFactory) it says:
> 
> <quote>
> If CDI is enabled, a BeanManager instance must be made available by the container. The
> container is responsible for passing this BeanManager instance via the map that is passed as
> an argument to the createContainerEntityManagerFactory call. The map key
> used must be the standard property name javax.persistence.bean.manager.
> </quote>
> 
> And then, 3.5.1 Entity Listeners, as partially quote by Scott earlier.
> 
> 
> On Mon 10 Jun 2013 03:46:01 PM CDT, Jason Greene wrote:
>> I guess the point I am still not clear on is exactly when the entities are instantiated. My understanding is that the earliest a user can cause a JPA impl load them is inside a PostConstruct method. That is unless JPA providers load instances for some kind of caching purposes?
>> 
>> On Jun 10, 2013, at 12:25 PM, Steve Ebersole <steve at hibernate.org> wrote:
>> 
>>> As Scott stated, Hibernate is doing the CDI calls as part of the
>>> EntityManagerFactory bootstrap (however that translates to WildFly
>>> deployment phases...).  There is a difficulty with delaying these CDI
>>> calls.  Getting around that would require either:
>>> 1) a 2-phase bootstrap process for the EntityManagerFactory.  Even
>>> though that proposal was not accepted into the JPA spec, I went ahead
>>> and broke out Hibernate's bootstrapping into a 2-phase process, so
>>> WildFly (via jipijapa) could leverage that.
>>> 2) Creating proxies of the listeners that delegate to the real listeners
>>> and perform the init on first call.  Ugh.  Proxies calling proxies
>>> calling proxies... not a recipe for great performance.  Not to mention
>>> don't call me to debug through that mess
>>> 
>>> There is a third option.  How entity listeners are built is hidden
>>> behind an interface (called ListenerFactory oddly enough).  I can expose
>>> that as an integration point for WildFly to be able to plug in whatever
>>> "delayed init" scheme it deems appropriate.  The only reason I'd suggest
>>> this is if y'all feel strongly about option 2 above (I'm not comfortable
>>> implementing that in the Hibernate code base).  But my vote would be for
>>> the first option.
>>> 
>>> I am open to other suggestions.
>>> 
>>> 
>>> On 06/10/2013 02:10 AM, Jozef Hartinger wrote:
>>>> Weld can be started before a JPA impl without a risk of suppressing
>>>> ClassFileTransformers under condition that all entities are annotated
>>>> with @Vetoed. We could document that as a requirement.
>>>> 
>>>> On 06/07/2013 06:20 PM, Scott Marlow wrote:
>>>>> For application deployments that use ClassFileTransformer to
>>>>> enhance/rewrite entity classes, we start the persistence unit service
>>>>> (PersistenceProvider.createContainerEntityManagerFactory()) during the
>>>>> Phase.FIRST_MODULE_USE (before any application classes have been loaded).
>>>>> 
>>>>> For application deployments that have an explicit CDI Bean Manager,
>>>>> there is a beans.xml that means the ClassFileTransformer will not work,
>>>>> since the CDI Bean Manager will scan all of the application classes
>>>>> (loading them), before the persistence unit service is started (so that
>>>>> the persistence provider can use CDI in entity listeners).
>>>>> 
>>>>> The same is also true for implicit CDI Bean manager support [1], expect
>>>>> all application deployments that contain an ejb3 module, will be wired
>>>>> for CDI (meaning JPA ClassFileTransformer support will work even less).
>>>>> 
>>>>> I raised this on the JPA 2.1 EG [2] in response to an earlier
>>>>> discussion, about switching to a two phase approach to address problems
>>>>> like this (didn't discuss CDI implicit support then but am raising that
>>>>> now).
>>>>> 
>>>>> [3] talks about why we don't create the CDI bean managers before the
>>>>> Install phase (would cause all application classes to be read which
>>>>> breaks JPA ClassFileTransformer use).
>>>>> 
>>>>> [4] is for adding implicit CDI support but is blocked currently by [5].
>>>>> 
>>>>> We can add persistence unit flags (jboss.as.jpa.classtransformer=false)
>>>>> for disabling JPA ClassFileTransformer support as a workaround but that
>>>>> doesn't help enough since many deployments will have implicit CDI
>>>>> support enabled (since they contain EJB modules).  We could add a way to
>>>>> disable implicit CDI support as another workaround for deployments that
>>>>> want to use ClassFileTransformer.
>>>>> 
>>>>> I'm not yet seeing a proper fix for this.  Anyone else?
>>>>> 
>>>>> Scott
>>>>> 
>>>>> [1] http://docs.jboss.org/cdi/spec/1.1/cdi-spec.html#bean_archive
>>>>> [2]
>>>>> https://java.net/projects/jpa-spec/lists/jsr338-experts/archive/2013-06/message/0
>>>>> [3] https://issues.jboss.org/browse/WFLY-1322
>>>>> [4] https://issues.jboss.org/browse/WFLY-476
>>>>> [5] https://issues.jboss.org/browse/WFLY-1463
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>> 
>> --
>> Jason T. Greene
>> WildFly Lead / JBoss EAP Platform Architect
>> JBoss, a division of Red Hat
>> 

--
Jason T. Greene
WildFly Lead / JBoss EAP Platform Architect
JBoss, a division of Red Hat