[cdi-dev] What about @AsyncObserves ?

[Antoine Sabot-Durand]

> Le 19 mars 2015 à 15:51, Romain Manni-Bucau <rmannibucau at gmail.com> a écrit :
> 
> sounds like a quick and dirty solution to me. @Async will arrive

Yes like in “Async is coming” ;)

> - maybe too early today - but adding @ObservesAsync just cause we dont have yet @Async will make this API obselete pretty quickly isn't it (already cause of EJB actually).

and if we add an @Async in our spec you think it’s better ?

> 
> Do we really want this feature at this price?

#1 requested feature by users.

> If yes AsyncObserves sounds an acceptable compromise but still will mess up the API IMO.

The question is “Is it more or less messy than @Async @Observes?"  I don’t know… It has pros and cons as I listed...

> 
> 
> Romain Manni-Bucau
> @rmannibucau <https://twitter.com/rmannibucau> |  Blog <http://rmannibucau.wordpress.com/> | Github <https://github.com/rmannibucau> | LinkedIn <https://www.linkedin.com/in/rmannibucau> | Tomitriber <http://www.tomitribe.com/>
> 2015-03-19 15:36 GMT+01:00 Antoine Sabot-Durand <antoine at sabot-durand.net <mailto:antoine at sabot-durand.net>>:
> Hi guys,
> 
> 
> So it seems impossible to avoid opt-in on the observer side for the sake of awkward compatibility.
> Adding a member to @Observes could also be a source of issues when old CDI lib will be used with CDI 2.0 runtime. Some of us (including me) don’t want to add an @Async annotation to CDI spec, so perhaps we should add an async alternative to @Observes with an @AsyncObserves or @ObservesAsync ?
> 
> So it would be
> 
> public void myObserver(@AsyncObserves payload) {}
> 
> instead of
> 
> @Async
> public void myObserver(@Observes payload) {}
> 
> 
> Pros :
> - it’s a cleaner way to manage the opt-in than to put 2 annotations or add a member to an existing one
> - it could have new members related to async behavior (context propagation, concurrent scenario, etc…)
> - As it won’t be in legacy code no risk to see old observers called asynchronously
> 
> Cons :
> - Still not clear for users when fire() is called to see @AsyncObserves launched synchronously
> - Yet another annotation added
> 
> wdyt ?
> 
> Antoine
> 
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