Re: [webbeans-dev] Producer fields on EJBs

Hi Guys, We need to resurrect this discussion.

I've committed a proposed SPI getFieldValue() method to http://anonsvn.jboss.org/repos/webbeans/ri/trunk/spi/src/main/java/org/jb... which I will wire into Web Beans now. Can anyone say if they vehemently disagree with this approach, or have some improvements to suggest? :-) Thanks! Pete On 16 Apr 2009, at 07:51, Andrew Lee Rubinger wrote: > Pete Muir wrote: >> I thought through this some, and bounced ideas off Andy. >> Gavin, I'm not sure that producer fields on SLSBs makes much sense >> - SLSBs instance state is undefined I think (some EJB expert >> correct if I'm wrong ;-). I think the spec should say that the >> behaviour of producer fields on SLSBs is undefined. >> Assuming the above, I would still argue for a getFieldValue SPI >> that throws IllegalStateException if invoked on an SLSB reference >> - and I think this removes the issue Ken has with a many-to-one >> instances. > > UnsupportedOperationException perhaps? > >> I'm slipping this for the upcoming release as we are too far from >> consensus. >> On 6 Apr 2009, at 18:22, Pete Muir wrote: >>> >>> On 6 Apr 2009, at 18:00, Kenneth Saks wrote: >>> >>>> >>>> On Apr 6, 2009, at 12:31 PM, Pete Muir wrote: >>>> >>>>> Carlo, Ken, Andrew, >>>>> >>>>> JSR-299 supports the notion of a producer field. By adding the >>>>> annotation @Produces to a field, you make it into a bean, which >>>>> can be used as the source of injections. The field can also be >>>>> associated with a scope. When you first look up an instance of >>>>> a bean, the field value is accessed, and stored in the context >>>>> for it's lifetime. >>>>> >>>>> As we deal with EJB references, we can't directly access the >>>>> field value (using reflection) so I think we should use the SPI >>>>> here. >>>>> >>>>> I propose we add a method with this signature to the >>>>> SessionObjectReference we previously created for the purpose of >>>>> casting/removing EJBs https://svn.jboss.org/repos/webbeans/ri/trunk/spi/src/main/java/org/jboss... >>>> >>>> There isn't necessarily a one-to-one relationship between an ejb >>>> reference and a bean instance. For stateless session beans, >>>> any one of the bean instances can be used for any invocation. >>>> >>>> Can't this behavior be handled by the web beans interceptor? By >>>> definition, each interceptor instance has the same life cycle as >>>> its associated bean instance, and the bean instance is available >>>> via the Interceptor InvocationContext. >>> >>> I did consider this, but not sure how to retrieve the result >>> invocationContext.getTarget() at the time it is needed for >>> accessing the producer field. We can't just store it from the >>> construction point onwards (serializability) and I can't see a >>> way to access it at some other point in the lifecycle - the only >>> way to run an @AroundInvoke is to call a method, and in this case >>> which method would you run, and how would you guarantee it has no >>> side effects? >>> >>>> >>>> >>>>> >>>>> /** >>>>> * Retrieve the value of a (possibly private) field >>>>> * >>>>> * @param field >>>>> * the field to retrieve the value of >>>>> * @return the retrieved value >>>>> * @throws IllegalArgumentException >>>>> * if the field doesn't exist on this session object >>>>> instance >>>>> */ >>>>> public Object getFieldValue(Field field); >>>>> >>>>> Any comments? >>>>> >>>>> >>>>> On 29 Mar 2009, at 22:57, Pete Muir wrote: >>>>> >>>>>> Ok, I would think that some language in the spec to hint at >>>>>> this might be good, as instances of session beans elsewhere in >>>>>> the spec implies a EJB reference. >>>>>> >>>>>> On 29 Mar 2009, at 18:04, Gavin King wrote: >>>>>> >>>>>>> Yes, this is a good question - the 299 implementation would >>>>>>> need >>>>>>> direct integration with the EJB container for this. (Not the >>>>>>> only >>>>>>> place this is needed.) >>>>>>> >>>>>>> >>>>>>> On Sat, Mar 28, 2009 at 7:18 PM, Pete Muir <pmuir(a)redhat.com&gt; >>>>>>> wrote: >>>>>>>> Hey >>>>>>>> >>>>>>>> Not quite sure how this is supposed to work as everywhere we >>>>>>>> hold a >>>>>>>> reference (proxy) to the EJB, and therefore don't have >>>>>>>> access to the >>>>>>>> instance and therefore can't get hold of the fields. Any >>>>>>>> pointers? >>>>>>>> >>>>>>>> Thanks! >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Pete Muir >>>>>>>> http://www.seamframework.org >>>>>>>> http://in.relation.to/Bloggers/Pete >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Gavin King >>>>>>> gavin.king(a)gmail.com >>>>>>> http://in.relation.to/Bloggers/Gavin >>>>>>> http://hibernate.org >>>>>>> http://seamframework.org >>>>>> >>>>>> -- >>>>>> Pete Muir >>>>>> http://www.seamframework.org >>>>>> http://in.relation.to/Bloggers/Pete >>>>>> >>>>>> _______________________________________________ >>>>>> webbeans-dev mailing list >>>>>> webbeans-dev(a)lists.jboss.org >>>>>> https://lists.jboss.org/mailman/listinfo/webbeans-dev >>>>> >>>>> -- >>>>> Pete Muir >>>>> http://www.seamframework.org >>>>> http://in.relation.to/Bloggers/Pete >>>>> >>>> >>>> _______________________________________________ >>>> webbeans-dev mailing list >>>> webbeans-dev(a)lists.jboss.org >>>> https://lists.jboss.org/mailman/listinfo/webbeans-dev >>> >>> -- >>> Pete Muir >>> http://www.seamframework.org >>> http://in.relation.to/Bloggers/Pete >>> >>> _______________________________________________ >>> webbeans-dev mailing list >>> webbeans-dev(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/webbeans-dev >> -- >> Pete Muir >> http://www.seamframework.org >> http://in.relation.to/Bloggers/Pete >> _______________________________________________ >> webbeans-dev mailing list >> webbeans-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/webbeans-dev > > -- > Andrew Lee Rubinger > Sr. Software Engineer > JBoss, a division of Red Hat, Inc. > http://exitcondition.alrubinger.com > _______________________________________________ > webbeans-dev mailing list > webbeans-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/webbeans-dev