[cdi-dev] [JBoss JIRA] (CDI-408) bean-discovery-mode="annotated" and Producers/Observers in @Dependent beans

Antoine Sabot-Durand (JIRA) issues at jboss.org
Tue Mar 18 11:00:13 EDT 2014

    [ https://issues.jboss.org/browse/CDI-408?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12953881#comment-12953881 ] 

Antoine Sabot-Durand commented on CDI-408:

Yes [~pmuir] and [~jason.greene] we all agrre on that (I hope so) for me it was implicit that option 3) includes a mention in the spec regarding that, while option 2) would warn the user at boot time.

Now the majority chose the option 3  (aka the RTFM option) we should be sure that the spec include something about it : "you shouldn't use default bean discovery mode to use Producers and Observers or annotate the beans that contains them with bean defining annotation (that's pretty clear). Should we spread it in different chapters (Producers and Event) or should we put it somewhere else ?

> bean-discovery-mode="annotated" and Producers/Observers in @Dependent beans
> ---------------------------------------------------------------------------
>                 Key: CDI-408
>                 URL: https://issues.jboss.org/browse/CDI-408
>             Project: CDI Specification Issues
>          Issue Type: Clarification
>          Components: Beans
>            Reporter: Jens Schumann
>            Assignee: Antoine Sabot-Durand
>              Labels: CDI_spec_chge
>             Fix For: 1.2 Proposed
> Right now bean-discovery-mode="annotated" skips beans that are not annotated with an bean-defining annotation even if they contain an observer method or producer method/field. I would not recommend having (not annotated) @Dependent beans with @Observes or @Produces - I just had them by accident while playing around with Wildfly.
> However there are two impacts:
> 1. Someone might be confused by ignored @Producer's. Not a major issue here, the CDI runtime will report it. We could optionally document the behavior in the spec, so it's clear to everyone. However I think it's inconsistent, since @Produces may contain a scope (and has a default scope too). Therefore I would vote for @Produces support in bean-discovery-mode="annotated". Of course the enclosing class is not a managed bean that may be injected somewhere.
> 2. Since Observer methods in "not annotated" beans fail silently this can be a major issue for applications, especially if you migrate from CDI 1.0 (CDI 1.0 source code and CDI 1.0 thinking model). Therefore I believe @Observer methods have to be included in bean-discovery-mode="annotated" even if the enclosing bean does not have a bean-defining annotation. Of course the enclosing class is not a managed bean that may be injected somewhere.
> I understand that the proposal above might have negative impacts on class scanning performance in bean-discovery-mode="annotated". However silently failing @Observes can be a major cause of defects that have to be treated because of technical and political reasons. Technical - because it may cause bugs. And political - because in my experience many people are still skeptical that CDI events are a trustworthy achievement[1]. Possibly skipped observer methods won't make live easier.
> If you believe the proposal would kill the original intent of bean-discovery-mode="annotated" please document the impact for Producers and Observers in the spec and even in the XSD.
> --
> [1] I have trained a couple hundred people in using CDI and CDI events. And every time I have to argument against the uncertainty on event delivery: "How do I know which observers are active?", "Who ensures that event's are delivered?"... I personally LOVE events;)
> Btw: Which JIRA version is CDI 1.1 Final? 

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