[webbeans-dev] Re: Hierarchical Managers

[Gavin King]

OK, here's a first draft of the definition of child managers, assuming
the simpler solution (1).

Please take a look at sections 11.7 and 11.2 and let me know your feedback.

On Thu, Dec 4, 2008 at 1:19 PM, Gavin King <gavin at hibernate.org> wrote:
> I've discovered a problem with setCurrent(scopeType).
>
> What if I called:
>
>   child1.setCurrent(BusinessProcessScoped.class)
>   child2.setCurrent(SessionScoped.class)
>
> Then I would have an ambiguity about "which" current manager was
> intended, since there is no definable ordering between these to
> scopes.
>
> There's two possible solutions to this:
>
> (1) Limit setCurrent() to the request scope, and require that the
> orchestration framework take care of propagation to other requests.
> (2) Say that if 2 different current contexts have different child
> managers defined, an exception is thrown
>
> Which option do you think we should go for?
>
> On Thu, Nov 27, 2008 at 4:30 PM, Gavin King <gavin at hibernate.org> wrote:
>> On the concall, we made some significant progress with the design for
>> hierarchical Managers. We decided to develop the following approach:
>>
>> (1) web beans belonging to a child manager may have any scope
>> (2) each child manager has its own set of contexts (there is a
>> parallel context hierarchy for each scope) that "belong" to, and have
>> the same lifecycle as, the parent contexts
>> (3) therefore the web beans belonging to the child are not visible to
>> web beans belonging to the parent
>> (4) however, web beans belonging to the parent *are* visible to web
>> beans belonging to the child
>> (5) a child manager may be associated with a context by calling
>> Manager.setCurrent(ScopeType), and is then automagically propagated
>> with the context
>> (6) web beans belonging to the child manager may be obtained via EL
>> evaluation whenever the child manager is in scope, or by directly
>> calling a getInstance() method of the child manager
>>
>> The needed API changes are as follows:
>>
>> Manager {
>>    public Manager createChild();
>>    public void setCurrent(Class<? extends Annotation> scope);
>>    public void validate();
>> }
>>
>> Context {
>>    getChild(Manager childManager);
>> }
>>
>> There is one question remaining open:
>>
>> Should it *ever* be possible to access a web bean belonging to the
>> child manager via a reference that was injected into a web bean
>> belonging to the parent manager or into some non-contextual object
>> such as a servlet or MDB?
>>
>> For example, we might choose to support this in the case that the
>> child manager web bean specializes the parent manager web bean.
>>
>> Bill, is this a feature that Oracle requires? If not, I'm inclined to
>> *not* support it in web beans 1.0.
>>
>> --
>> 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
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