[webbeans-dev] How does JSF deal with managed beans when Web Beans/299 is present?

[Pete Muir]

On 3 Aug 2009, at 19:09, Dan Allen wrote:

> A switch is reasonable, but I think it needs to disable more than  
> just annotation-defined managed beans support. My understanding is  
> that a JSF managed bean defined in faces-config.xml can still have a  
> @PostConstruct annotation that gets processed (same with the other  
> life cycle annotations and the @EJB annotation). Then it's still  
> possible that there is an instance of an application-scoped eager  
> bean in the JSF managed bean container. Same would go for beans in  
> other scopes.

Hmm, this is a tricky one. The spec doesn't define any guidance about  
how to migrate from one model to the other. I would like to hear from  
Gavin what the EGs ideas here are before proceeding.

I would have thought that faces-config.xml can define a lot of info  
about the bean which should still be used when 299 is present, to  
provide the easiest migration path. Perhaps this is something for an  
addon, and the JSF managed bean facility should just be completely  
turned off if 299 is present.

>
> We should state that it's possible to inject a managed or enterprise  
> bean into a JSF managed bean because the injection, as you said, is  
> based on the EL.

Why? If you are using 299 you aren't using JSF managed beans. If you  
are aren't using 299 then this isn't relevant.

> If the injection goes the other way, the instance is the one created  
> by JSR-299 and not the instance created by JSF; an important point  
> to understand. Therefore, there could be two instances of a bean per  
> scope. And from what you proposed, the JSR-299 bean always wins if  
> it has the same name as a JSF managed bean.

Again, no, if 299 is active *it* manages the beans, so there are no  
JSF managed beans.

>
> -Dan
>
> On Sun, Aug 2, 2009 at 6:38 PM, Pete Muir <pmuir at redhat.com> wrote:
> Hi
>
> I realized we have a potential conflict between JSF and 299 to do with
> EE defined managed beans, which we need to address. Imagine the
> following scenario: A managed bean is defined using @ManagedBean in a
> war in which both JSF and Web Beans is enabled. In this case both JSF
> and Web Beans will attempt to manage the bean, however according to
> the latest note sent by Roberto Chinnici to the EE expert group, if
> 299 is present, 299 should manage the bean. We need to address how to
> deal with this for both Web Beans and Mojarra.
>
> Some points to consider:
>
> * 90% of the time there is no problem, the Web Beans ELResolver is
> installed before the JSF ManagedBeanELResolver. However the corner
> case of an eager instantiated, application scoped managed bean with a
> post construct lifecycle callback will cause us a problem. There may
> also be other corner cases we haven't considered. For this reason, I
> think we should consider being able to explicitly disable JSF managed
> beans
> * this doesn't affect other specs which may use managed beans as much,
>   (a) as Mojarra works in other containers than GlassFish, such as
> Tomcat, where Web Beans may not be present
>   (b)  299 specifically states that JSF should use an ELResolver as
> it's integration point (other specs integration point is programatic
> and so can use an SPI if or similar - Ken's suggestion from our latest
> meeting for those who were there)
> * Mojarra will need to continue to provide xml-defined managed beans
> when Web Beans/299 is present.
>
> My suggested solution is to simply have a switch in Mojarra we can use
> to "turn off" annotation-defined managed beans support (either
> automatic via detection of WEB-INF/beans.xml or manual via web.xml or
> programatically).
>
> Pete
>
> On 31 Jul 2009, at 20:11, Barbara Louis wrote:
>
> > - How we deal with jsf managed beans when 299 is present?
> > - 299 requires managed beans
> > - JSF RI will need to make the change - the ques to ask is: should
> > jsf manage the managed beans or should I let the EE container to
> > manage it for me?
> > - Pete will send an email on webbeans dev mailing list on this topic
> > and include Mojarra mailing list (webtier at glassfish.dev.java.net)
>
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>
>
> -- 
> Dan Allen
> Senior Software Engineer, Red Hat | Author of Seam in Action
> Registered Linux User #231597
>
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