[cdi-dev] [JBoss JIRA] (CDI-129) Clarify behaviour of @ApplicationScoped in EARs

Mark Struberg (JIRA) jira-events at lists.jboss.org
Wed Oct 17 12:38:01 EDT 2012

    [ https://issues.jboss.org/browse/CDI-129?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12727346#comment-12727346 ] 

Mark Struberg commented on CDI-129:

Do you have the code somewhere? What I observed in JBossAS and Glassfish is that the WebApp which touches the shared MailService the first time will do all the injection based on the active beans in this very webapp. Regardless if the resolved Bean<X> is visible in the other webapps or not. This is not only wrong but might in some cases even create the obvious NoClassDefFound and similar (great candidate: serialisation time).

Of course one could argue this is an impl bug, but otoh how to implement that correctly? 
And now we are back to the 3 listed ways to do it:
1.) injecting only other beans of the shaed-lib and completely ignore anything defined in the webapps. Jozefs way is technically valid, but a no-go from a user perspective imo as it would lead to having different contextual instances for the same injection points across your application.

2.) restricting @Specializes and @Alternatives to only shared libs. This is technically valid as well but this restriction is certainly not covered by the spec.

3.) make @ApplicationScoped 1 per WAR and thus remove the problem with scopes over multiple isolation levels. All our classloader slices would always see exactly 1 well defined scenario. We should nonetheless think about any scope broader than 1 per war in CDI-1.1, but for CDI-1.0 it would perfectly work (And to repeat again: this is also what is explicitly stated in the spec 2.4.1).

> Clarify behaviour of @ApplicationScoped in EARs
> -----------------------------------------------
>                 Key: CDI-129
>                 URL: https://issues.jboss.org/browse/CDI-129
>             Project: CDI Specification Issues
>          Issue Type: Clarification
>          Components: Contexts
>    Affects Versions: 1.0
>            Reporter: Mark Struberg
>            Assignee: Pete Muir
>             Fix For: 1.1 (Proposed)
> Since @ApplicationScoped currently is defined in 6.5.2 as to be 'like in the Servlet specification' this means that you will get a new instance for every WebApplication (WAR file).
> There is currently no specified CDI scope for providing a single shared instance for a whole EAR.
> We could (ab-)use @Singleton for that, but this is currently not well defined at all.
> Alternatively we could introduce an own new annotation like @EnterpriseScoped or likes. 

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