[weld-dev] @Resource annotation handling by Weld vs Servlet container

[Jan Bartel]

Hi Weld developers,

The Jetty project is looking at how we can do a tighter integration
with Weld, also with a view to discussions in the Servlet Spec 4
committee to alleviate the necessity for CDI implementations to
maintain jetty-specific initialisation code.

During investigations, I noticed that we seem to have a conflict in
the handling of a few annotations for classes that are managed by the
servlet container (ie servlets, filters, listeners etc):

@Resource
@PostConstruct
@PreDestroy

As Jetty puts a servlet/filter/listener into service, we introspect
the class and find the above annotations and process them. It seems
that Weld does too, as I see the following failure for this code
snippet:

public class TestListener implements ServletContextListener
{
    @Resource(mappedName="maxAmount")
     private Double maxAmount;
}


javax.naming.NameNotFoundException; remaining name 'maxAmount'
    at org.eclipse.jetty.jndi.local.localContextRoot.lookup(localContextRoot.java:429)
    at org.eclipse.jetty.jndi.local.localContextRoot.lookup(localContextRoot.java:533)
    at javax.naming.InitialContext.lookup(InitialContext.java:411)
    at org.jboss.weld.injection.spi.helpers.AbstractResourceServices.resolveResource(AbstractResourceServices.java:48)
    at org.jboss.weld.injection.spi.helpers.AbstractResourceServices$1.createResource(AbstractResourceServices.java:121)
    at org.jboss.weld.injection.AbstractResourceInjection.getResourceReference(AbstractResourceInjection.java:44)
    at org.jboss.weld.injection.AbstractResourceInjection.injectResourceReference(AbstractResourceInjection.java:53)
    at org.jboss.weld.util.Beans.injectEEFields(Beans.java:344)
    at org.jboss.weld.injection.producer.ResourceInjector$1.proceed(ResourceInjector.java:69)
    at org.jboss.weld.injection.InjectionContextImpl.run(InjectionContextImpl.java:48)
    at org.jboss.weld.injection.producer.ResourceInjector.inject(ResourceInjector.java:72)
    at org.jboss.weld.injection.producer.BasicInjectionTarget.inject(BasicInjectionTarget.java:121)
    at org.jboss.weld.environment.servlet.inject.AbstractInjector.inject(AbstractInjector.java:55)
    at org.jboss.weld.environment.jetty.JettyWeldInjector.inject(JettyWeldInjector.java:15)
    at org.jboss.weld.environment.jetty.WeldDecorator.decorate(WeldDecorator.java:105)
    at org.eclipse.jetty.util.DecoratedObjectFactory.decorate(DecoratedObjectFactory.java:77)
    at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:335)
    at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1349)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1342)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:743)
    at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:257)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:505)


Googling around, it is not clear to me exactly which of the Common
Annotations (JSR250) that Weld supports and I'd appreciate some input
from the Weld devs in order for Jetty to work out how best to move
forward with Weld integration.

In particular, I'd appreciate some clear feedback on which of the
following @Resource annotation usages will be handled by Weld:

@Resource on a class
@Resource on a field
@Resource on a method
@Resource annotations without an accompanying @Producer annotation

Secondly, as can be seen from the stacktrace above, Weld is failing to
find the matching JNDI entry for an @Resource annotation. This is
because Weld appears not to be looking in "java:comp/env" namespace,
although IIRC that is mandated by the JavaEE spec for EE managed
classes (servlets/filters/listeners etc). So if Jetty delegates
handling of some/all processing of @Resource, how do we ensure that
Weld will be able to find the right JNDI entry?

thanks for your time,
Jan
-- 
Jan Bartel <janb at intalio.com>
www.webtide.com
'Expert Jetty/CometD developer,production,operations advice'