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From Lars-Fredrik Smedberg <itsme...@gmail.com>
Subject CDI spec question on interceptors, alternatives and priority
Date Wed, 15 Jun 2016 13:00:35 GMT
Hi!

Was not sure what mailing list to send this to but I guess some of you
could help me out.

We are moving to JEE 7 and we are annotating our interceptors with
@Priority(...) to not have to include them in all beans.xml in all archives
where they should be used.
The value for the @Priority annotation are based upon the constants defined
in Interceptor.Priority... which JavaDoc says "Interceptors with smaller
priority values are called first."... so far so good...

Then I also want to be able to place alternatives in separate modules/jars
that we will use in some test environments. This also works good using
@Alternative and @Priority... I understand
that the alternative is activated by using the @Priority annotation. In
section 5.2.2 of the CDI 1.2 spec (e.g.
http://docs.jboss.org/cdi/spec/1.2/cdi-spec-1.2.pdf) I read the following:

"...all the beans left are alternatives with a priority, or producer
methods or fields of beans that
are alternatives with a priority, then the container will determine the
highest priority value, and
eliminate all beans, except for alternatives with the highest priority..."

I have tested this and I'm fine with that the higher priority alternative
is choosen. However in same spec in section 4.3 they have the following
example:

"@Alternative @Priority(APPLICATION+100)
public class MockAsynchronousService extends AsynchronousService {"

Similar example can be found at e.g.:
https://docs.oracle.com/javaee/7/tutorial/cdi-adv002.htm

To me its confusing to use a priority value based on Interceptors.Priority
since the semantics of the Priority value is the opposite for interceptors
and alternatives?

Does the examples for alternatives only confuse me or did I miss someting?

Best regards
Lars-Fredrik Smedberg

-- 
Med vänlig hälsning / Best regards

Lars-Fredrik Smedberg

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