[cdi-dev] Support Request (and Conversation?) Scope in @Singleton @Startup @PostConstruct methods

[Mark Struberg]

Folks, again and again and again: 


@ConversationScoped EntityManager is broken, broken, broken. The EM is per JPA spec NOT Serializable and thus must not get stored in the Session.
There are some impls which _are_ Serializable, but those are not JPA spec compliant (e.g. avajé eBean). With the mandatory support of locking and pessimistic locking it is just technically impossible to implement a Serializable EntityManager.



>>  Moreover, quoting https://issues.jboss.org/browse/CDI-148 ("There is 
> no reason why the ConversationScope should be any less available than the 
> RequestScope"),
Well, there is a difference between a Servlet-Request and a JSF-Request. The difference is subtle but important. The JSF-Request is e.g _not_ available in some ServletFilters which are outside of the JSFs FacesServlet handling. The CDI spec states this in 6.7.4:

> If the conversation associated with the current JSF request is in the transient state at the end of a JSF request,
> it is destroyed, and the conversation context is also destroyed. 

But the Request Context lives much longer! It will also be available in various ServletFilters and Listeners. Thus the statement is not entirely correct.


>  to be allowed to use it @Singleton @Startup @PostConstruct methods.
Of which Beans are you talking here? EJBs? CDI managed beans? Which @Singleton annotation? the one from JSR-330 or EJB?

Please also note that the JSR-330 @Singleton is imo completely useless because it's underspecified. "Singleton" in which _context_? 

1 per WebApp?

1 per EAR?
1 per JVM?
1 per Cluster?


LieGrue,
strub

----- Original Message -----
> From: Pete Muir <pmuir at redhat.com>
> To: Guido Bonazza <guidbona at yahoo.com>
> Cc: "cdi-dev at lists.jboss.org" <cdi-dev at lists.jboss.org>
> Sent: Tuesday, March 6, 2012 10:30 AM
> Subject: Re: [cdi-dev] Support Request (and Conversation?) Scope in @Singleton @Startup @PostConstruct methods
> 
> Please file a CDI issue :-)
> 
> On 2 Mar 2012, at 13:36, Guido Bonazza wrote:
> 
>>  Hello everyone!
>>  Checking out the CDI 1.0 spec and actually trying it on JBoss AS 
> 7.1.0.Final it seems to me that the Request Scope is not active in @Singleton 
> @Startup @PostConstruct method, so I'd like to propose this use case to be 
> supported in the next version of CDI.
>>  Moreover, quoting https://issues.jboss.org/browse/CDI-148 ("There is 
> no reason why the ConversationScope should be any less available than the 
> RequestScope"), I think that conversation scope should be available too in 
> this context. It would be very useful, for example, when you have an 
> EntityManager produced in conversation scope (mostly used in JSF contexts), to 
> be allowed to use it @Singleton @Startup @PostConstruct methods.
>>  Of course there should be some limitations in this case (long running 
> conversation promotion shouldn't be allowed for example), but the basic case 
> should be supported in my opinion.
>> 
>>  Thanks for the attention,
>>       Guido
>> 
>>  _______________________________________________
>>  cdi-dev mailing list
>>  cdi-dev at lists.jboss.org
>>  https://lists.jboss.org/mailman/listinfo/cdi-dev
> 
> 
> _______________________________________________
> cdi-dev mailing list
> cdi-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/cdi-dev
>