[webbeans-dev] Re: Redefinition of @New / clarification of injection for non-contextual instances

[Pete Muir]

I like this a lot :-)

https://jira.jboss.org/jira/browse/WBRI-101


On 14 Jan 2009, at 13:55, Gavin King wrote:

> OK, here's a writeup.
>
> Please look at sections 3.2.5, 3.3.6 and 5.14. This is a low-impact  
> change.
>
> On Wed, Jan 14, 2009 at 11:46 PM, Gavin King <gavin at hibernate.org>  
> wrote:
>> It gets better. If you declare <New/> as the binding for a bean
>> defined in XML, you can override the injection metadata for
>> non-contextual instances.
>>
>> Excellent!
>>
>> OK, I'm wrong about this solution being non-satisfying. It's
>> completely satisfying.
>>
>> On Wed, Jan 14, 2009 at 11:43 PM, Gavin King <gavin at hibernate.org>  
>> wrote:
>>> There's one important thing that is not especially well-defined in  
>>> the
>>> spec today and that has been bothering me for a while. It's to do  
>>> with
>>> injection into non-contextual bean instances.
>>>
>>> There are a couple of cases where the spec supports injection into
>>> non-contextual bean instances:
>>>
>>> * session beans obtained using JNDI lookup or direct injection  
>>> using @EJB
>>> * @New
>>>
>>> In each of these cases you get an instance of a bean which is *not*
>>> bound to the scope declared by the bean. However, the spec still
>>> requires injection into the bean instance.
>>>
>>> However, there may be multiple "beans" (i.e. instances of Bean) of  
>>> the
>>> given type:
>>>
>>> * one defined using only annotations
>>> * others defined using XML
>>>
>>> and each "bean" may have different dependencies defined.
>>>
>>> So the question naturally arises: when I obtain this instance from
>>> JNDI or using @New or @EJB, exactly *which* "bean" is it an instance
>>> of? i.e. which set of bean metadata should be used?
>>>
>>> I've not found any completely satisfying answer to this question -  
>>> but
>>> there's only one possibility that is truly well-defined:
>>>
>>> * it is the one defined using annotations ... even if that bean  
>>> has a
>>> disabled deployment type!
>>>
>>> I've been thinking about how best to characterize this in the spec,
>>> and I think the answer is slightly surprising.
>>>
>>> We should say that for each bean type, there is one extra "bean", so
>>> we now have:
>>>
>>> * the one defined using only annotations
>>> * one that is exactly the same, but with scope @Dependent, binding
>>> @New and deployment type @Standard
>>> * the others defined using XML
>>>
>>> We can now characterize session beans obtained using JNDI lookup or
>>> @EJB as instances of the bean with binding @New, removing the
>>> ambiguity.
>>>
>>> This approach lets me eliminate section 3.10 (yay!), since there  
>>> is no
>>> longer anything special/magical about @New, and replace it with some
>>> shorter notes in 3.2/3.3.
>>>
>>> Even better, you'll no longer have to use the concrete type of the
>>> bean when you inject using @New. This is especially useful for  
>>> session
>>> beans with no bean class local view.
>>>
>>> So this turns out to be simultaneously a simplification, enhancement
>>> and clarification of the spec, and it's also easier to implement!
>>>
>>> Does that make sense to everybody?
>>>
>>> Anyway, I guess I will write this up so you guys can see what it  
>>> looks
>>> like in the spec.
>>>
>>>
>>> --
>>> Gavin King
>>> gavin.king at gmail.com
>>> http://in.relation.to/Bloggers/Gavin
>>> http://hibernate.org
>>> http://seamframework.org
>>>
>>
>>
>>
>> --
>> Gavin King
>> gavin.king at gmail.com
>> http://in.relation.to/Bloggers/Gavin
>> http://hibernate.org
>> http://seamframework.org
>>
>
>
>
> -- 
> Gavin King
> gavin.king at gmail.com
> http://in.relation.to/Bloggers/Gavin
> http://hibernate.org
> http://seamframework.org
> <Web Beans  
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