[jsr366-experts] Re: Compatibility Problems with MR Resource Annotation Widening

From: Bill Shannon <bill.shannon_at_oracle.com>
Date: Fri, 27 Feb 2015 15:38:53 -0800

Jason Greene wrote on 02/27/15 09:51:
>> On Feb 26, 2015, at 9:02 PM, Jason Greene <jason.greene_at_redhat.com> wrote:
>> So my recollection, was that this was intentional since the bindings arenít useful to CDI applications, and you could always reference another binding defined by a component which did support it, if you needed such behavior. The deployment descriptor for CDI doesnít allow you to override these bindings, and the other deployment descriptor locations donít cover the full set where @Resource can appear (for example ejb-jar overrides are defined on ejb components and not globally). Finally, @Resource (and the other EE bindings) can only appear on producer fields, which is a subset of what 250 defined.
>> Iíll ping Pete to see if he remembers the same, but yeah I agree the combination of the specs implies that it should work, other than the fact that it canít work the way the global rules are defined.
> BTW I confirmed that this matched Petes understanding as well.
> There was never any interest for CDI managed beans to support:
> - Creation of @Resource (et al) JNDI Bindings
> - Usage of @Resource (et al) Class declarations
> - Usage of @Resource (et al) Method injection
> These all have no benefit to CDI applications because they are all superseded by other constructs. The annotations were just reused for the ties just to avoid creating new ones.

Except that there's nothing anywhere in the spec that says in this specific
case you don't have to create the bindings that the spec says you have to
create. And for all the reasons described previously, we would not want
the spec to say that.

> In an early CDI draft there was a complete xml description language in beans.xml that could be used to override/define all aspects of CDI managed beans (including annotations). However, that was dropped since portable extensions allowed third party definitions of such a thing.

I only ever expected that to be able to change how @Inject worked, not
change how @Resource worked, since @Resource was defined by the platform
spec and not the CDI spec.

> The bindings, if desired for consistency purposes, could be addressed by the EE spec, and the existing CDI RI looks like it already can support that. Class declarations could likewise be addressed, but would probably require some CDI RI SPI improvements. Method injection on the other hand probably would require CDI spec involvement.

The platform spec clearly requires that these bindings are created, always.

If you extract all the annotation information from an application using
whatever technique you think is correct, turn it into the corresponding
deployment descriptor information, merge it into the deployment descriptors,
set metadata-complete, and remove all the annotations from the application,
will the behavior be the same? It should. That was clearly our intended
design when we introduced these annotations and extended the deployment
descriptors to allow injection to be specified.