I would say only @Metatype, because the various options it opens up are
unlimited! :-)
Maybe let it ride the waves for a while and do an EJB 3.2 bonus pack
after EE 7 with some common extensions.
The one thing I don't get is why @Metatype is a meta annotation in
itself. If it where I would expect it to be present when I query the
annotations. Given that it is a chicken/egg annotation, I did some
fiddling to come up with:
https://github.com/dblevins/metatypes/pull/1/files#L9R38 vs
https://github.com/dblevins/metatypes/pull/1/files#L3R147.
What did I miss?
Carlo
On 12/15/2011 03:51 AM, Marina Vatkina wrote:
> Do you mean various synonims or the @Metatype?
>
> Pete Muir wrote:
>> Surely to give users that option in a portable fashion, we need to
>> spec it?
>>
>> On 14 Dec 2011, at 04:37, Marina Vatkina wrote:
>>
>>> We can add ANNOTATION_TYPE (to all or to a subset of annotations). I
>>> think we shouldn't spec such meta-annotations, but rather give users
>>> an option to add annotations if they like it that way.
>>>
>>> But the "simplified" @Schedule versions can be confusing though,
>>> e.g. @Daily or @Yearly will need more details, like time of the day
>>> or day of the year, in which case they wont be shorter than the
>>> original - @Schedule() is daily at midnight, and
>>> @Schedule(dayOfMonth="1", month="1") is yearly on Jan 1st...
>>>
>>> My $.02. What do others think?
>>>
>>> Best,
>>> -marina
>>>
>>> David Blevins wrote:
>>>> I think this is too big for this spec round, but here is the idea
>>>> in more clear terms.
>>>>
>>>> Yes, it is very much like CDI stereotypes. It's also very much
>>>> like Bean Validation's ability to reuse annotations. It's also
>>>> like CDI @InterceptorBinding and @Qualifier which also have "meta"
>>>> effects associated with them -- i.e. annotations that use them
>>>> effectively become @InterceptorBindings and @Qualifiers.
>>>>
>>>> We're doing this all over the place really. It's not entirely CDI
>>>> or Bean Validation specific. It's not EJB specific either, so let's
>>>> try not to look at it and get distracted with the whole align EJB
>>>> and CDI initiative.
>>>>
>>>> The twist here is that you can "reuse" annotations which aren't
>>>> designed to be applicable to @Target(ANNOTATION_TYPE). The syntax
>>>> for it is IMO ugly but effective. If we don't want that twist, we
>>>> can easily go simpler.
>>>>
>>>> This is really a design pattern and not specification specific. If
>>>> there is an idea of specification, it would be a Java SE -- it
>>>> would be quite handy to be able inherit annotations in this fashion
>>>> at a language level and not need the cooperation of specific apis.
>>>>
>>>> For our purposes, we could just as easily decide to add
>>>> ANNOTATION_TYPE to all our current annotations and make a simple
>>>> rule that "annotations with the ANNOTATION_TYPE can be used as
>>>> meta-annotations" and just leave it at that.
>>>>
>>>> Without something like "@Metatype" that model doesn't become
>>>> recursive, but maybe that's good enough. The "@Metatype" concept
>>>> is a simple statement of "carry these annotations forward". A
>>>> simple and explicit statement of how far you want the recursion to go.
>>>>
>>>> So here is an exploration of how meta-annotations (annotation
>>>> reuse) could be applied to EJB:
>>>>
>>>> https://github.com/dblevins/metatypes/tree/master/metatype-ejb/src/main/java/javax/ejb/meta
>>>>
>>>>
>>>> The above is a list of "built-in" meta-annotations we might
>>>> consider delivering out of the box. I've put them in a theoretical
>>>> "javax.ejb.meta" package to make it clear that all the annotations
>>>> there are simply repackaged versions of the actual annotations.
>>>>
>>>> Plummed this into a patched version of CXF's JAX-RS support and
>>>> it's proving to be quite fun there as well:
>>>>
>>>> @GET
>>>> @Path("/customers/{id}/")
>>>> public Customer getCustomer(@Id String id) {
>>>> }
>>>>
>>>> The applicability to other specs is that part that gives me most
>>>> pause. It certainly belies the need for a more generic form of
>>>> annotation reuse that isn't specific to a domain like EJB, CDI,
>>>> Bean Validation, etc. We keep creating domain-specific annotations
>>>> to drive this form of recursion or reuse and really we just need
>>>> one for the whole language.
>>>>
>>>> It's interesting and fun, but perhaps too young for inclusion. Or
>>>> not.
>>>>
>>>>
>>>> -David
>>>>
>>>>
>>