[webbeans-dev] Producer fields on EJBs
Pete Muir
pmuir at redhat.com
Fri Jul 31 10:52:52 EDT 2009
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/jboss/webbeans/ejb/api/SessionObjectReference.java
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/webbeans/ejb/api/SessionObjectReference.java
>>>>
>>>> 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 at redhat.com>
>>>>>>> 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 at 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 at 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 at 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 at 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 at 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
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