Hi Ed
But still the change discussed here (let CDI manage #{facesContext} )
has its problems.
Right now we have these methods:
FacesContext.getCurrentInstance();
// protected
FacesContext.setCurrentInstance(FacesContext instance);
FacesContext.getELContext();
The problem is this: In JSF we are used to call
FacesContext.getCurrentInstance(), but on the ELResolver we take
the FacesContext instance from the ELContext. Yes, there is a
circular reference here. The default implementation of FacesContext
wraps ELContext and add the reference. That is preferred, because
it avoids calls to FacesContext.getCurrentInstance().
Who knows this detail? JSF. Who is responsible for create and
destroy FacesContext? JSF. Who should have control over how
#{facesContext} is resolved? JSF.
I don't see difficult to provide a CDI extension inside JSF to deal
with FacesContext problem. The only thing you need to realize is
you can use a wrapper or proxy, so the instance in the bean should
not be the same instance. To get the inner instance you can always
use getWrapped() method.
I know it is easier just to burn the code inside CDI, but my question is
if this has really sense or not, from a design perspective. It just sounds
too inconvenient for me, because you are losing a lot of flexibility
in the implementation, and this is not something you must do inside
CDI, it is something where we can choose, and if we have an option,
why don't choose keep it under JSF control?.
regards,
Leonardo Uribe
2014-10-06 15:16 GMT-05:00 Edward Burns <edward.burns_at_oracle.com>:
>>>>>> On Mon, 6 Oct 2014 14:35:58 -0500, Leonardo Uribe <leonardo.uribe_at_irian.at> said:
>
> LU> The problem is we introduce a dependency in CDI for JSF, unless we get
>
> Well, we're not *introducing* a dependency. We are adding more weight
> to a dependency we already have.
>
> LU> There is no real advantage to do that. As far as I remember, CDI is an
> LU> optional dependency, even if there are classes in JSF that use CDI
> LU> api, you can run JSF without CDI. Does that will change with JSF 2.3?
>
> You are right that prior to JSF 2.3, it was possible to use a subset of
> JSF features on containers that did not provide CDI. We are indeed
> proposing to change that in JSF 2.3, making CDI required. This change
> is most strongly articulated in [1287-RedefineManagedBeansAsCDIBeans].
> In addition to this change, we are also requiring Java EE 8 and Java SE
> 8 in order to run JSF 2.3.
>
> We realize these two changes are departures to our decade old policy of
> lagging one version behind the platform. We reasoned that if people
> have stuck with JSF for this long, they would be willing to move up to
> EE 8 as well.
>
> LU> I think CDI provides a pluggable API that works for our needs. The
> LU> only thing that I miss about that API is that you can't control class
> LU> scanning, and that causes problems because application servers
> LU> sometimes need to customize that part.
>
> Yes, this is one of those areas that CDI hasn't fully addressed yet.
> However, we believe we can mitigate the impact of this by not even
> saying anything about CDI's pluggable API.
>
> Ed
> --
> | edward.burns_at_oracle.com | office: +1 407 458 0017
> | 24 work days til Devoxx 2014