[weld-dev] CDI and @Singleton

Fri Nov 22 09:46:54 EST 2013

On 11/22/2013 03:37 PM, Antoine Sabot-Durand wrote:
> I don’t totally agree on your point Martin : @Dependent scope is not a normal scope as well but I can inject a dependent scope bean in a normal scope bean.
That is a very good example because the situation with @Dependent and 
@Singleton is actually equivalent. You can inject both into a 
normal-scoped bean. However, you must take care of passivation if you 
inject into a passivating bean. This is because, as Martin mentioned, 
Weld does not consider @Singleton normal nor passivating (because no 
spec says so).

>
> I don’t say it’s a bug since the spec seems to be a bit blur on the subject.
>
> I wanted just to stress that
>
> 1. Singleton don’t behave like Application Scope as it was evoked in this thread
> 2. Weld behavior changed from version 1 to 2
The difference probably is that now Weld validates upfront and detects 
the problem whereas with Weld 1 your @SessionScoped bean would only fail 
to serialize at runtime.
> 3. Singleton is now, nearly useless since I can’t make it interact with other scope. and if something can’t be used can we say we implemented it ;) ?
It can as long as passivation is dealt with.
>
> Antoine
>
>
> Le 22 nov. 2013 à 12:53, Martin Kouba <mkouba at redhat.com> a écrit :
>
>> Antoine, I think the Weld 2.x behaviour is correct per the spec.
>> GlobalRepositoryImpl is not a passivation capable dependency (@Singleton
>> is not a normal scope)...
>>
>> M
>>
>> Dne 22.11.2013 11:54, Antoine Sabot-Durand napsal(a):
>>> In my experience, Weld 1.1.x supported @Singleton,
>>> Weld 2.x don’t support them (or not in same way).
>>>
>>> In Agorava roadmap I plan to provide implementation on other JSR 330 framework than CDI, so I have a module containing only JSR 330 compliant code. In this module I defined a Bean « GlobalRespository » with @Singleton scope. In my CDI module this bean is injected in a SessionScoped bean (inCookieProducer). Under Jboss AS 7.1.1, Glassfish 3.1.2 and EAP 6.1 the code works nicely.
>>> With Wildfly 8 and Glassfish 4.0, I have this exception when my web app start :
>>>
>>> Caused by: org.jboss.weld.exceptions.UnserializableDependencyException: WELD-001413: The bean Managed Bean [class org.agorava.cdi.InCookieProducer] with qualifiers [@Any @Default] declares passivating scope but has non-passivation-capable dependency Managed Bean [class org.agorava.oauth.GlobalRepositoryImpl] with qualifiers [@Any @Default]
>>> 	at org.jboss.weld.bootstrap.Validator.validateInjectionPointPassivationCapable(Validator.java:461)
>>> 	at org.jboss.weld.bootstrap.Validator.validateInjectionPointForDeploymentProblems(Validator.java:386)
>>> 	at org.jboss.weld.bootstrap.Validator.validateInjectionPoint(Validator.java:282)
>>> 	at org.jboss.weld.bootstrap.Validator.validateGeneralBean(Validator.java:133)
>>> 	at org.jboss.weld.bootstrap.Validator.validateRIBean(Validator.java:164)
>>> 	at org.jboss.weld.bootstrap.Validator.validateBean(Validator.java:507)
>>> 	at org.jboss.weld.bootstrap.ConcurrentValidator$1.doWork(ConcurrentValidator.java:68)
>>> 	at org.jboss.weld.bootstrap.ConcurrentValidator$1.doWork(ConcurrentValidator.java:66)
>>> 	at org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:60)
>>> 	at org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:53)
>>> 	at java.util.concurrent.FutureTask.run(FutureTask.java:262) [rt.jar:1.7.0_45]
>>> 	... 3 more
>>> As a workaround I had to create a @Specialize bean of my @Singleton only to set it in @ApplicationScope.
>>>
>>> Antoine Sabot-Durand /@antoine_sd
>>> ———————————————
>>> CDI co-spec lead
>>> CDI eco-system development
>>> Agorava tech lead
>>>
>>>
>>> Le 22 nov. 2013 à 09:24, Jozef Hartinger <jharting at redhat.com> a écrit :
>>>
>>>> Weld supports it but because of the reasons stated by Mark I would
>>>> recommend avoiding it.
>>>>
>>>> On 11/22/2013 08:19 AM, Mark Struberg wrote:
>>>>> Hi Bill!
>>>>>
>>>>> This pops up quite often.
>>>>> Actually the spec is pretty much silent on this and defines nothing else than CDI being based on JSR-330. But the TCK defines that any JSR-299 container also must fully pass the JSR-330 TCK as part of the compatibility check.
>>>>>
>>>>> Means CDI containers need to support it, but it is not really defined how it should behave.
>>>>> In OWB we just treat it as alias for @ApplicationScoped. I'm not 100% sure if it's the same for Weld, but I think to remember discussing about it with either Jozef or Pete that they do it effectively the same way. Needs ack from them though.
>>>>>
>>>>> My personal suggestion is to avoid it.
>>>>>
>>>>> There is a slightly broader issue hidden in this topic actually.
>>>>> As per explanation above, each CDI container must also support scopes annotated with @Scope (from atinject, not @NormalScope from CDI). But atinject does nowhere define how to register Contexts for those scopes. In CDI we should do pickup contexts for those scopes but it's probably not well tested nor defined how those contexts should behave.
>>>>> I'd personally would expect them to just get injected without the Contextual Reference proxies but as direct Contextual Instances and otherwise be pretty much the same like standard CDI scopes. But that needs ack + wordig by my fellow CDI EG members.
>>>>>
>>>>>
>>>>> LieGrue,
>>>>> strub
>>>>>
>>>>>
>>>>>
>>>>> ----- Original Message -----
>>>>>> From: Bill Burke <bburke at redhat.com>
>>>>>> To: Weld <weld-dev at lists.jboss.org>
>>>>>> Cc:
>>>>>> Sent: Friday, 22 November 2013, 3:17
>>>>>> Subject: [weld-dev] CDI and @Singleton
>>>>>>
>>>>>> Is Weld or CDI supposed to recognize and support @javax.inject.Singleton
>>>>>> annotated classes?
>>>>>>
>>>>>> -- 
>>>>>> Bill Burke
>>>>>> JBoss, a division of Red Hat
>>>>>> http://bill.burkecentral.com
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>>>>>>
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