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

[Scott Marlow]

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