[jsr-314-open] annotation scanning (was Re: Meeting minutes from EG face-to-face at Sun's SF office post-JavaOne)

[Dan Allen]

On Thu, Jun 11, 2009 at 4:21 PM, Pete Muir <pmuir at redhat.com> wrote:

> As I understand it, the problem here (especially with the Servlet spec) is
> that there is no limiting which jars can contain annotations, so every class
> must be checked. There are various optimizations you can do (the obvious one
> is to exclude all known library jars which don't contain annotations). NB
> this isn't such a problem with 299 as it carefully limits which jars need to
> be scanned.


Exactly. The very definition of a scan is widely divergent. Seam (and Web
Beans) have taken the approach of looking for a marker file using
getResources() and scanning the associated classpaths. I brought up this
style in the meeting.

The approach by JSF is to look in WEB-INF/classes and in each JAR file in
WEB-INF/lib. This is problematic if you happen to have an external
classpath. One case is when you run Jetty from Maven. A more common case is
when you have another EE module, such as an EJB-JAR.

The Servlet spec seems to be suggesting that every classpath visible to the
application is going to be scanned, which is terribly reckless in my opinion
(I'm sure others).

So we need consistency in what is scanned, and then need a way to leverage a
container-provided scanning mechanism, if available (obviously in a
standalone environment you have to bring your own scanner).

-Dan

-- 
Dan Allen
Senior Software Engineer, Red Hat | Author of Seam in Action

http://mojavelinux.com
http://mojavelinux.com/seaminaction
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