[seam-dev] Extending weld-extensions generic beans

[Stuart Douglas]

So this is going to be much harder to implement than I thought. Because I want to look at the types that come through ProcessAnnotatedType I need to install the generic beans using AfterBeanDiscovery.addBean. This is much harder to use for this purpose than BeforeBeanDiscovery.addAnnotatedType, and no matter what I do there will be subtle and not so subtle differences between these beans and 'native' weld bean (e.g. interceptors and decorators won't work). 

Ideally it would also be possible to do AfterBeanDiscovery.addAnnotatedType, however for the moment the only real solution that I can see is to put this functionality in the XML module, and require the extension developer to explicitly declare their generic beans in XML. This way all the information is available in BeforeBeanDiscovery, and I can add the generic beans using addAnnotatedType. 

I think the syntax would be something like this:

<genericBean class="org.jboss.seam.DroolsConfiguration">
   <d:KnowledgeBaseProducer/>
   <d:KnowledgeSessionProducer/>
</genericBean>

Does this sound like a reasonable solution?

Stuart

________________________________________
From: seam-dev-bounces at lists.jboss.org [seam-dev-bounces at lists.jboss.org] On Behalf Of Tihomir Surdilovic [tsurdilo at redhat.com]
Sent: Tuesday, 13 April 2010 12:18 AM
To: seam-dev at lists.jboss.org
Subject: Re: [seam-dev] Extending weld-extensions generic beans

On 4/12/10 9:51 AM, Stuart Douglas wrote:
> After talking with Tihomir over the last few days about the seam-drools module I think that there is base functionality that is missing that belongs in weld-extensions as it is similar to the existing generic bean code.
>
> I will use an example from the drools module to outline the problem:
>
> The drools module has a DroolsConfiguration object that contains configuration, this can be installed via XML and there can be multiple DroolsConfigrations per app. for every DroolsConfiguration several object need to be produced e.g. KnowledgeBase, StatefullKnowledgeSession and a KnowledgeRuntimeLogger.
>
> currently we would need to do something like this:
>
> <  d:DroolsConfiguration>
>    <app:SomeQualifier>
>    ...configuration
> </d:DroolsConfiguration>
>
>
> <d:KnowlegdeBaseProducer>
>    <d:producerMethod>
>      <app:SomeQualifier>
>      <s:parameters>
>        <d:DroolsConfiguration>
>         <s:Inject/>
>         <app:SomeQualifier/>
>       </d:DroolsConfiguration>
>      </s:parameters>
>    </d:producerMethod>
> </d:KnowlegdeBaseProducer>
>
> ...same for StatefullKnowledgeSession, StatelessKnowledgeSession, KnowledgeRuntimeLogger etc.
>
> and wire up a producer like that for every object being created from the DroolsConfiguration. This is not good. The user should be able to just wire up the configuration and the rest of the beans should be created automatically. I think we should be able to do something like this:
>
> @Generic(DroolsConfiguration.class)
> class KnowledgeBaseProducer
> {
>    @Produces
>    @GenericQualifiers
>    public KnowledgeBase producerMethod(@Inject @GenericQualifiers DroolsConfiguration config )
>    {
>     //do stuff
>    }
>
and also disposer methods with for example:
void disposerMethod(@Disposes @GenericQualifiers KnowledgeBase kbase)
{
...
}

Thanks!
> }
>
> @Generic tell the extensions to register a new KnowledgeBaseProducer bean for every DroolsConfiguration found.
> @GenericQualifiers is replaced with the qualifiers on the DroolsConfiguration object when the bean is added.
>
> This means that all an end user has to do is wire up a single DroolsConfiguration object and everything just works.
>
> Does this sound like a good idea? Is there anything I have overlooked?
>
> Stuart
>
>
>
> _______________________________________________
> seam-dev mailing list
> seam-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/seam-dev
>
>

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