[javaee-spec users] [jsr342-experts] Re: EJBs and JTA transactional interceptors

From: Deepak Anupalli <>
Date: Fri, 10 Feb 2012 17:37:27 +0530


I guess the purpose of adding transaction support for Interceptors is to
enable CMT for bean components other than EJBs. So naturally having these
interceptors applied to CMT enabled EJB beans sounds like overkill.

Considering the amount of complex exception handling wording we may have to
introduce and confuse the users, the best option would be to opt out this
functionality from EJBs.

My preference would be 3. Comments inline

> -----Original Message-----
> From: Bill Shannon []
> Sent: 31 January 2012 02:10
> To:
> Subject: [jsr342-experts] EJBs and JTA transactional interceptors
> We've been trying to figure out how the new JTA transactional interceptor
> support should interact with EJBs. Here's some options we've considered:
> 1. The new transaction annotations are not allowed to be used on EJBs.
> This error would be detected at deployment time.
> 2. The new transaction annotations have no effect when used on EJBs.
> This would likely be very surprising to users.
> 3. The EJB container does not understand the new transaction annotations
> at all and behaves the same with regard to the exceptions that are
> as it would if the application were to throw the same exceptions in
> an EJB that was not annotated with the new transaction annotations.
> The exceptions the EJB container sees at point B above are handled
> the same as they would be if CDI were removed from the picture.
> The EJB container does exception wrapping and transaction rollback
> based only on its existing rules, including use of the existing
> EJB @ApplicationException annotation. At point A the application
> sees exceptions that might be wrapped in the normal EJB way.
> Note that the EJB container will be performing its normal CMT
> behavior, including the default transaction attribute of REQUIRES
> and the normal EJB exception wrapping behavior. If the EJB Bean
> wants to use the new JTA transaction annotations it will likely want
> to disable the EJB CMT support by specifying an EJB transaction
> attribute of SUPPORTS (which means the EJB container will never
> start a transaction itself and will pass through any existing
> transaction context).


Making the CMT configuration SUPPORTS for EJBs allows eventually phasing out
EJB CMT support and move towards the Interceptor based approach which is
uniform across components and more appealing to the non-EJB community.

This approach definitely makes way for both the models to co-exist, and the
developer has an option to choose at the Bean/Jar Levels.

> 4. Like #3, but the EJB container understands both the existing
> EJB @ApplicationException annotation as well as any new such
> annotation defined by JTA. This changes which exceptions will
> be wrapped before returning to the application, and what will
> happen to any transaction that the EJB container might have started.
> And like #3, the application will likely want to disable EJB CMT
> by specifying an EJB transaction attribute of SUPPORTS.
> 5. Like #4, but the EJB container also detects the use of the new
> JTA transaction annotations and changes the default CMT behavior
> And like #4, the EJB container still does its normal exception
> 6. Like #5, but the EJB container also changes the exception wrapping
> rules to match those of a standalone CDI bean using the new JTA
> transaction annotations (i.e., no exception wrapping at all).
> In cases #5 and #6, it's TBD what should happen if the bean uses both the
> transaction annotations and the JTA transaction annotations.
> Given a possible implementation (see appendix), you can predict the
> but it's almost certainly not what the user wants, and so likely should be
> treated as an error, probably detected at deployment time.
> The current EJB exception wrapping behavior is somewhat arcane. You could
> imagine a new EJB annotation @DontWrapExceptions that would disable this
> behavior. This could be used explicitly in cases
> #3 - #5 (it's implicit in case #6), or in other existing uses of EJB.
> Note that remote EJBs would need to continue to follow the existing rules
> for remote exceptions.
> Which option above do you prefer?
> --- Appendix (read only if you're confused)
> For the options #3 - #6, it's helpful to think about how this might be
> implemented. For example, consider an implementation where the EJB
> container asks CDI to instantiate the class that is the EJB bean. CDI
> injection on the bean and returns a wrapper or subclass of the bean that
> handles any interceptors declared for the bean. The EJB container then
> invokes methods on the bean using this object reference returned by CDI.
> The EJB container does no interceptor handling of its own. This may or
> not be a reasonable or correct implementation approach, but for the
> purposes of the following, let's consider it. Here's a picture:
> app reference ----> EJB container ----> CDI ----> EJB bean
> A B