[jsr-314-open] request for listeners to support container injection and life-cycle callbacks

[Steve Roy]

It would be nice if the design made it easy for resources to be released
when the beforePhase/afterPhase processing completes so developers don't
inadvertently forget to release expensive resources.
I can see the need for the feature. There is a danger though, that it makes
it too easy for developers to implement time & resource expensive operations
for invocations of the JSF lifecycle, which should be considered time
sensitive.

- steve

On Tue, Jul 21, 2009 at 1:35 PM, Dan Allen <dan.j.allen at gmail.com> wrote:

> On Tue, Jul 21, 2009 at 1:08 PM, Kito Mann <kito.mann at virtua.com> wrote:
>
>> On Tue, Jul 21, 2009 at 12:42 AM, Dan Allen <dan.j.allen at gmail.com>wrote:
>>
>>> One of the questions that is often raised when discussing Java EE
>>> integration (JSR-299 and EJB) is how to get a reference to a
>>> container-managed resource from within a JSF listener (e.g., EJB session
>>> bean, BeanManager, EntityManager). While Java EE certainly provides
>>> mechanisms to lookup up a resource, such as through JNDI, I think we need to
>>> restate the question at hand. Why is it that JSF listeners don't support
>>> Java EE resource injection like managed beans. Requiring this functionality
>>> in a Java EE environment would go a long way towards making JSF extensions
>>> (such as Seam or ADF) portable and generally make the effort of integration
>>> w/ container-managed resources easier.
>>>
>>> With that said, I would like to propose for the next rev of the JSF
>>> specification that listeners, in addition to managed beans, support
>>> container injection and life-cycle callbacks when JSF is run in a Java EE
>>> environment (the rule for servlet containers would parallel that of managed
>>> beans today).
>>>
>>> Listeners include:
>>>
>>> PhaseListener
>>> SystemEventListener
>>> BehaviorListener? (not sure)
>>
>>
>> So the easiest way to do this would be to accept an expression any time a
>> listener is declared, correct? This is possible today with the <f:view> tag
>> for PhaseListeners, but not in faces-config.xml. In the other cases, we do
>> have support for expressions.
>>
>
> I think you may be looking at it too narrowly. What we really want is for
> listeners to be managed beans, since most of the Java EE platform is going
> in that direction (and in some regards already there). We don't want
> something JSF-specific like EL expressions being passed in. What we really
> want is @PostConstruct, resource injection, etc. In other words, we want
> these classes to work within the context of the Java EE environment, rather
> than as outliers.
>
> -Dan
>
> --
> Dan Allen
> Senior Software Engineer, Red Hat | Author of Seam in Action
> Registered Linux User #231597
>
> http://mojavelinux.com
> http://mojavelinux.com/seaminaction
> http://in.relation.to/Bloggers/Dan
>
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