[cdi-dev] BeanManager visiblity and container archives

[Christian Kaltepoth]

Hey all,

I would like to bring up an issue that we ran into while preparing Ozark
(the MVC 1.0 RI) to be usable as a container module in Glassfish. We
discussed this issue on Slack and discovered that Mojarra (JSF) and Soteria
(Security) had similar issues.

MVC 1.0 defines some extension points that users and 3rd party libraries
can implement to provide additional functionality. MVC uses CDI for looking
up all implementations of these extension point interfaces. Similar
concepts are used in in JSF. Historically JSF uses factories which users
can implement and register via faces-config.xml. Now for Java EE 8 it was
decided to prefer CDI to obtain such custom extension point implementations
(ViewHandler, NavigationHandler, etc). So basically JSF uses a similar
mechanism to lookup implementations of certain interfaces like MVC does.

As of today Ozark is basically a standard bean archive deployed together
with the application (in /WEB-INF/lib). Now we want to prepare Ozark to be
usable as a Glassfish module which is provided by the container. As CDI
doesn't discover bean archives installed as part of the container, we
wanted to basically remove beans.xml and provide an portable extension
which registers the required annotated types required for Ozark. AFAIK
Mojarra and Soteria are also doing it this way. Now as soon as we do this,
things are getting weird.

There are various ways to get a BeanManager to lookup beans provided by the
application:

   - CDI.current().getBeanManager()
   - @Inject BeanManager
   - JNDI lookup

Now if we try to lookup beans deployed with the application (in
/WEB-INF/classes or in a library in /WEB-INF/lib) we don't get consistent
results (many thanks to Arjan Tijms for doing all the testing):

   - In Glassfish we don't see application beans if we use the injected
   BeanManager. Looking up the BeanManager via JNDI or using
   CDI.current().getBeanManager() works fine.
   - In Wildfly CDi.current() doesn't seem to find beans deployed with the
   application. The injected BeanManager and the one looked up via JNDI works
   fine.

So it looks like there are quite some inconsistencies between
implementations here.

*To sum it up:* In Java EE 8 more and more specs rely heavily on CDI. And
many specs allow the user and 3rd party libraries to implement interfaces
to extend functionality. But it looks like looking up such beans deployed
with the application from a container archive isn't working in a consistent
way.

I hope my explanation of this complicated topic isn't too bad. I hope that
we can start some discussion around this. Some of you already joined the
discussion on Slack and the corresponding pull request, but I would prefer
to discuss this here. :)

Christian


-- 
Christian Kaltepoth
Blog: http://blog.kaltepoth.de/
Twitter: http://twitter.com/chkal
GitHub: https://github.com/chkal
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/cdi-dev/attachments/20160519/21624d6e/attachment.html