[cdi-dev] Clarification on 4.3 Specialization

[Emily Jiang]

Thank you Tom and Matej for your response!
The alternative was enabled in the archive beans-xml-modified.jar, but it
is not enabled in the archive beans-xml-modified2.jar. The issue is not
with alternative but with Specialized.

At the moment, Weld specialized is effective even if itself is not enabled,
which is not desirable because it disables other bean but itself is not
enabled. As a consequence, this causes deployment error.

The CDI 1.2 section 4.3  spec says:
When an enabled bean, as defined in Section 5.1.2, “Enabled and disabled
beans”, specializes
a second bean, we can be certain that the second bean is never instantiated
or called by the
container. Even if the second bean defines a producer or observer method,
the method will never
be called.

It is true the above sentence comments about an enabled bean. It hits an
disabled bean should not specialize a second bean. If you guys think it is
unclear, can we update the spec to clarify this scenario?

By the way, OWB and Weld behave differently (Weld thinks a disabled bean
still specializes a second bean while OWB thinks a disabled bean does NOT
specialize a second bean). This is something we can leave to
implementation. We should spec it!

On Mon, Nov 23, 2015 at 8:45 AM, Matej Novotny <manovotn at redhat.com> wrote:

> Hello Emily
>
> I agree with Tom. In your case, specialized producer is enabled (via
> beans.xml) although only per bean archive.
>
>
> And about this:
> >>From Weld's perspective, any bean annotated with @Specialized disables a
> second bean regardless whether itself is active or not.
>
> It is true, however the spec doesn't define how does a @Specialized bean
> behave when it is disabled (or at least I haven't found that bit).
> So this leaves it up to implementation and I can't really see a problem
> with it. Why would you create a @Specialized bean and disable it afterwards
> (with no other @Specialized and/or @Alternative active)?
>
>
> Matej
>
> ----- Original Message -----
> From: "Tomas Remes" <tremes at redhat.com>
> To: "Emily Jiang" <emijiang6 at googlemail.com>
> Cc: "cdi-dev" <cdi-dev at lists.jboss.org>
> Sent: Monday, November 23, 2015 8:33:44 AM
> Subject: Re: [cdi-dev] Clarification on 4.3 Specialization
>
>
> Hi Emily,
>
> I am not sure I follow. What is disabled?
> AlternativeCounterProducerModified? I can see
> AlternativeCounterProducerModified is enabled in beans.xml of the given
> bean archive and it means it is selected alternative only per the bean
> archive. So I can't see any problem (or maybe I don't fully understand).
>
> Tom
>
> ----- Original Message -----
> From: "Emily Jiang" <emijiang6 at googlemail.com>
> To: "cdi-dev" <cdi-dev at lists.jboss.org>
> Sent: Sunday, November 22, 2015 10:42:29 PM
> Subject: Re: [cdi-dev] Clarification on 4.3 Specialization
>
> any thoughts?
>
> Should a bean with @Specialize disable a bean even if it is disabled
> itself?
>
> On Thu, Nov 19, 2015 at 10:09 AM, Emily Jiang < emijiang6 at googlemail.com
> > wrote:
>
>
>
>
> I have an application containing two wars.
>
> testDiffBDA.war
> testDiffBDA.war/WEB-INF/classes/test/diff/web/FrontEndServlet.class
>
> @Inject CounterProducerConsumerModified2 bean;
>
>
> beans-xml-modified2.jar
> containing one bean and an empty-ish beans.xml :
> @Inject at CounterModifiedQualifier String modifiedProducer;
>
> beans-xml-modified.jar.jar
> CounterModifiedQualifier (the interface)
> CounterProducerModified (the bean implementing that interface)
> AlternativeCounterProducerModified (an alternative specialized bean)
> beans.xml
> <alternatives>
>
> <class>com.ibm.jcdi.test.beansxml.AlternativeCounterProducerModified</class>
> </alternatives>
>
> My application failed deployment with the error on Weld but worked on
> OpenWebBeans
>
> [ERROR ] CWWKZ0004E: An exception occurred while starting the application
> testDiffBDA. The exception message was:
> com.ibm.ws.container.service.state.StateChangeException:
> org.jboss.weld.exceptions.DeploymentException: WELD-001408: Unsatisfied
> dependencies for type String with qualifiers @CounterModifiedQualifier
> at injection point [BackedAnnotatedField] @Inject
> @CounterModifiedQualifier
> com.ibm.jcdi.test.beansxml.CounterProducerConsumerModified2.modifiedProducer
> at
> com.ibm.jcdi.test.beansxml.CounterProducerConsumerModified2.modifiedProducer(CounterProducerConsumerModified2.java:0)
> --
>
>
> After further investigation and talking to Martin from Weld, the error was
> caused due to the fact of AlternativeCounterProducerModified disabling the
> CounterProducerModified bean but itself is not enabled in the jar of
> beans-xml-modified2.jar. Therefore, no producer is active to produce a bean
> with the qualifier CounterModifiedQualifier.
>
> From Weld's perspective, any bean annotated with @Specialized disables a
> second bean regardless whether itself is active or not.
>
> My understanding is that the specialized should only take effect if itself
> is enabled. Otherwise, we run into the situation of where the specialized
> bean is not enabled but it disabled another bean. To me, it is wrong.
>
>
> I also checked the spec:
> @Alternative @Specializes
> public class MockAsynchronousService extends AsynchronousService {
> ...
> }
> When an enabled bean, as defined in Section 5.1.2, “Enabled and disabled
> beans”, specializes
> a second bean, we can be certain that the second bean is never
> instantiated or called by the
> container. Even if the second bean defines a producer or observer method,
> the method will never
> be called.
>
> The spec says only an enabled bean can specialize a second bean. I would
> like to know what other people think.
>
>
> Thanks
> Emily
> =================
> Emily Jiang
> ejiang at apache.org
>
>
>
> --
> Thanks
> Emily
> =================
> Emily Jiang
> ejiang at apache.org
>
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> --
> Tomas Remes
>
>
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> intellectual property rights inherent in such information.
>



-- 
Thanks
Emily
=================
Emily Jiang
ejiang at apache.org
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