[cdi-dev] Recap of Context Management (CDI-30) hangout meeting

[Mark Struberg]

Martins argument with Quartz is a good one. 


Having 2 different ways to do the same thing might be making things too complicated. You also have to think about what happens if a user or libraries would mix the 2 approaches?

So my vote is for the programmatic approach. 


Oh and while we are at it:
If we introduce some 'RequestContextControl' bean, should it also contain a isActive() method? Otherwise we might get into troubles with nesting such code.
Of course it is possible by code like


try {
  beanManager.getContext(RequestScoped.class);
  // request context is active
} 

catch (ContextNotActiveException cnae) {
  // request context is not active
  // start it etc.

}


But that seems a bit heavyweight, isn't?

LieGrue,
strub



On Thursday, 29 September 2016, 11:58, Antoine Sabot-Durand <antoine at sabot-durand.net> wrote:


>
>
>That's also my choice:
>We should provide 2) for advance usage and consistency sake if we go for Session context control later AND we should provide 1) for an easy usage of this feature.
>
>
>A well written JavaDoc should prevent confusion between both approach.
>
>
>Antoine
>
>On Thu, Sep 29, 2016 at 11:46 AM Martin Kouba <mkouba at redhat.com> wrote:
>
>
>>Dne 29.9.2016 v 11:16 Antoine Sabot-Durand napsal(a):
>>> Hi all,
>>>
>>> Just to sum up what was said during our Tuesday Hangout meeting. For
>>> those who were present feel free to correct or amend this.
>>>
>>> Controlling Request Context is something rather easy (because it's
>>> linked to one thread) while Session Context is far less obvious (used
>>> across multiple threads) so providing a generic solution to deal with
>>> their control seems quite complicated.
>>> That's why we decided to start addressing the Request Context control
>>> first and if we fell happy with that, continue the work on the Session
>>> Context.
>>>
>>> Public API to control the request context could be design in 2 different
>>> ways:
>>> 1) provide an interceptor to activate request context during the
>>> intercepted method invocation
>>
>>This approach is also not always usable in some integration use cases
>>where the request cannot be simply "wrapped in a single method call".
>>
>>For instance, in Quartz scheduler you can register a job listener with
>>methods jobToBeExecuted(), jobExecutionVetoed() and jobWasExecuted() -
>>here the approach 2) would make sense. On the other hand, you could
>>implement a JobFactory so that Job instances are beans (or at least
>>instances obtained and injected from an InjectionTarget) and simply
>>associate interceptor binding for its execute() method.
>>
>>> 2) provide a programmatic API accessible thru a bean (like the
>>> Conversation bean)
>>>
>>> First solution is probably the easiest way for end user (to avoid not
>>> ended context), but if we go for controlling Session Scope we won't be
>>> able to provide a simple interceptor for it and will design something
>>> like solution 2 for it.
>>>
>>> So the question is should we go for 1 or 2 or both (with a risk of
>>> confusion) ?
>>
>>I think that both ways are legal and make sense.
>>
>>>
>>> Thanks for your feedback
>>>
>>> Antoine
>>>
>>>
>>>
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