On Thu, Jul 30, 2009 at 10:34 AM, Haroon
Rafique<haroon.rafi...@utoronto.ca> wrote:
> Hi Wes,
>
> I don't know much of the details about the JEE spec, however, I can share
> my implementation with you. The code is not in production yet, so caveat
> emptor (it works for us, for now in development).
>
> I use glassfish as my app server. To expose local EJB interfaces within
> our entire application, I use an EJBInvokerServlet (uses the @EJB and
> @EJBs annotations). The listing is as follows (took out package and import
> statements and anonymized):
>
> �...@ejbs(
> value = {
> �...@ejb(beanInterface = Local1.class, name = "ejb/local1"),
> �...@ejb(beanInterface = Local2.class, name = "ejb/local2"),
> }
> )
> /**
> * Used to make local interfaces of listed EJBs available within the whole
> * web application.
> */
> public class EJBInvokerServlet extends HttpServlet {
> }
>
> The other way to inject beans is by specifying <ejb-local-ref> inside web.xml.
> <ejb-local-ref>
> <ejb-ref-name>Local1Bean</ejb-ref-name>
> <ejb-ref-type>Session</ejb-ref-type>
> <local>Local1</local>
> </ejb-local-ref>
> I prefer the Servlet approach as its simpler.
>
> Wherever we need the EJBs to be automagically injected (the container does
> its part because of EJBInvokerServlet), we then use the @Resource
> annotation, e.g., to inject the Local1 interface, I would use:
>
> �...@resource(mappedName = "ejb/local1")
> private Local1 local1;
>
> Hope that helps.
Haroon, it does and it doesn't. @EJB/@EJBs and @Resource aren't the
only DI annotations that are part of the EE specs. This is the problem
Robin has with the existing integration plugins. My understanding of
what he wants is that he wants to be able to use other annotations
(like @PersistenceContext) on fields in a struts action and have those
fields injected.
To turn it around and consider it compared to another similar
plugin... In the spring plugin, we delegate the class instantiation to
spring, then spring can decide what needs injected, etc. based on
spring configuration. What I'd like to do is apply the same concept to
EE. To do this in spring, there is an implementation of the
ObjectFactory that first tries to instantiate objects using spring,
and when that fails, it falls back on traditional xwork instantiation
(reflection-based). Once the object is created, the spring object
factory then checks to see if it can autowire the instance (based on
plugin configuration).
I'd like to try a similar approach with EE. The hard part is that I
don't know what API, or where to look for an API that instantiates EE
objects. Spring has 'applicationContext.getBean', is there something
similar for EE? Even if it's not as easy as Spring, I'm still willing
to wade through it for a bit since it seems like it would be useful to
at least a few users. The advantage to an object factory based EE
plugin is that I don't need to be aware of the annotations at all, I'd
be delegating that sort of thing to the EE app server's own
mechanisms.
-Wes
--
Wes Wannemacher
Head Engineer, WanTii, Inc.
Need Training? Struts, Spring, Maven, Tomcat...
Ask me for a quote!
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