[cdi-dev] @Destroyed(ApplicationScoped.class)

[Mark Struberg]

Hi Antonin!

BeforeShutdown is a system event and thus must only be observed by Extensions. 

You can do what you intended by simply listening to @PreDestroy in any @ApplicationScoped bean.

> For the information, calling BeanManager.getReference in BeforeShutdown actually works in Weld 2.x (I haven’t tested that use case in OWB).

I expect this to work in OWB as well. The spec is slightly ambiguous when it comes to the ApplicationContext. On the one hand it defines that if only must be started after AfterDeploymentValidation and shut down before BeforeShutdown. But then again all Extensions are provided as @ApplicationScoped beans and you can inject those in any Extensions Observer Method and even send events between them. But that requires the ApplicationContext to be active way earlier resp longer. Both those functions are afaik even TCK tested.

LieGrue,
strub


> Am 29.04.2015 um 11:23 schrieb Antonin Stefanutti <antonin at stefanutti.fr>:
> 
> Hi,
> 
> That somehow relates to the BeforeShutdown lifecycle event which must be fired after the container has finished processing requests and destroyed all contexts.
> 
> IMO, it would make sense / be useful to be able to execute logic on ApplicationScoped beans from within extensions before they are about to be "destroyed".
> 
> In the example from the specification (and consistently with other lifecycle events), one can retrieve a reference to the bean manager:
> 
> void beforeShutdown(@Observes BeforeShutdown event, BeanManager manager) { ... }
> 
> While that is not clearly stated in the specification (as opposed to the clarification done in version 1.2 for events like AfterBeanDiscovery and AfterDeploymentValidation), I induce that methods likegetReference are supposed to systematically throw ContextNotActiveException.
> 
> To still meet the need, that is external control over ApplicationScoped bean destruction without relying on the @PreDestroy callback nor disposer method, an intermediate lifecycle event may be introduced, similarly to @Initializing / @Destroying(ApplicationScoped.class). Interestingly enough, the specification states that the application scope is active [...] when the disposer method or @PreDestroy callback of any bean with any normal scope other than @ApplicationScoped is called, which tends to validate John's "lower scopes" hypothesis.
> 
> For the information, calling BeanManager.getReference in BeforeShutdown actually works in Weld 2.x (I haven't tested that use case in OWB).
> 
> Antonin
> From: cdi-dev-bounces at lists.jboss.org <cdi-dev-bounces at lists.jboss.org> on behalf of Romain Manni-Bucau <rmannibucau at gmail.com>
> Sent: Tuesday, April 28, 2015 10:14 PM
> To: John D. Ament
> Cc: cdi-dev at lists.jboss.org
> Subject: Re: [cdi-dev] @Destroyed(ApplicationScoped.class)
>  
> Tcks check this event is "accessible" which is important otherwise it is just useless
> What is not well defined is integration with other parts of ee.
> Le 28 avr. 2015 21:00, "John D. Ament" <john.d.ament at gmail.com> a écrit :
> Your understanding matches my understanding, and matches what I typically tell people to do (use @PreDestroy).
> 
> I think this is more of a use case for lower scopes, or for a dependent bean (which I would imagine would receive this event, though I can't say I've tried).
> 
> John
> 
> On Tue, Apr 28, 2015 at 2:56 PM Mark Struberg <struberg at yahoo.de> wrote:
> Hi!
> 
> The CDI-1.2 spec says in 6.7.3:
> 
> „An event with qualifier @Initialized(ApplicationScoped.class) is fired when the application context is initialized and an event with qualifier @Destroyed(ApplicationScoped.class) is fired when the application is destroyed. "
> 
> Now from the pure wording („IS initialized“, „IS destroyed“) I’d say that both events must be fired _after_ the state is reached. Means _after_ the context got initialized and _after_ the context got destroyed.
> 
> Means an observer like
> 
> @ApplicationScoped
> public class MyBean {
>   public void endIt(@Observes @Destroyed(ApplicationScoped.class) endObject) {
>     doSomething()
>   }
> }
> 
> will _never_ get invoked.
> Because the bean (and the whole context) will be already killed…
> 
> You can observe this event in a @Singleton scoped bean, but not in an @ApplicationScoped bean.
> If you like to do _that_, then simply use a @PreDestroy.
> 
> Do others share this interpretation? Do we need to clarify anything?
> 
> LieGrue,
> strub
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