[slf4j-dev] jcl-over-slf4j module not building

[Ceki Gülcü]

John,

With the recent changes made by Sebastien [1, 2], we no longer have
packages split across modules. Thus,

slf4j-api
exports  packages:
   org.slf4j
   org.slf4j.spi
   org.slf4j.helpers
imports packages:
   org.slf4j.impl

slf4j-BINDING (where BINDING is one of nop, simple, log4j12, etc)
exports packages:
   org.slf4j.impl
imports packages:
   org.slf4j
   org.slf4j.spi
   org.slf4j.helpers

As things stand currently, I believe that we are close to a release
candidate. The remaining question is with respect to OSGi
meta-data. Do we keep using maven-bundle-plugin or not? In particular,
does that plug-in support Require-Bundle directives? (I think that
Require-Bundle directives would be necessary.)

Comments/thoughts?

[1] http://www.slf4j.org/pipermail/dev/2007-February/000818.html
[2] http://www.slf4j.org/pipermail/dev/2007-February/000874.html


At 11:45 PM 2/20/2007, John E. Conlon wrote:
>Ceki Gülcü wrote:
> > John,
> >
> > Do you have a suggestion how we could avoid duplication of slf4j-api
> > classes in the various bindings? Can this be done using 
> maven-bundle-plugin ?
> >
>At the moment I can think four approaches to removing the duplication of
>classes in the bindings that sit on 'Sally's application's classpath.
>
>1. Keep the packages split across the api and binding projects, continue
>to rely on single classloader joining at runtime, and move back to a
>Require-Bundle approach for osgi support. We won't need the
>maven-bundle-plugin in the binding projects for this.
>
>2. Remove the split packages by consolidating the packages into the api
>and binding jars, and use a 'service implementation' discovery similar
>that suggested by Eric in the "aufgeregt" thread :-) :
>
>http://www.qos.ch/pipermail/logback-user/2007-February/000129.html
>
>We should not depend on a sun impl for this so we would have to provide
>our own implementation, Boris has provided an example at:
>
>http://marc.theaimsgroup.com/?l=slf4j-dev&m=117157566417290&w=2
>
>While I have not experimented with his code, I do see one area that
>would require a change for it to work in an OSGi environment.
>
>  public Object obtainFactory(ClassLoader cl) {
>         ILoggerFactory ret = null;
>         InputStream is = cl.getResourceAsStream(SERVICE_ID);
>
>Note: couldn't use a context classloader as it would not find the
>classes in an OSGi runtime. Sun's service api offers similar signatures.
>
>3. Keep split packages and retain current way of combining api and
>bindings.  Remove OSGi decorations and maven-bundle-plugin from the five
>bindings projects.   Create five additional OSGi 'pom' projects that
>just wrap the api and bindings to create OSGi binding bundles.  These
>projects would only have a pom.xml (no code) and the artifacts they
>create would be the same bundles as we are now producing in the binding
>projects.  All other projects producing native jar/osgi bundles (like
>the adapters) would remain unchanged.
>(In this case Sally would not use the osgi-xxx-binding bundles.)
>
>4. Convince Sally to run OSGi ;-)
>
>  From an OSGi perspective I would rate them in order of functionality
>from higher to lower - 4, 3, 2, 1.
>
>kind regards,
>John
>
>
>
> > At 07:52 PM 2/19/2007, Ceki Gülcü wrote:
> >
> >
> >> At 08:25 PM 2/18/2007, John E. Conlon wrote:
> >>
> >>
> >>>> Assuming Maven 2 is used by all participants, without particular
> >>>> action by Sally, slf4j-api would be packaged in the final
> >>>> application along with a user-chosen binding, say slf4j-log4j12. In
> >>>> that case, we would have the contents of slf4j-api project duplicated,
> >>>> once in slf4j-api.jar and once in slf4j-log4j12.jar. It would most
> >>>> probably work as expected, but I don't think it's good practice to
> >>>> have class files duplicated.
> >>>>
> >>>>
> >>> I don't like this class duplication either, but AFAIK given the same
> >>> classloader this should not matter.  The same classloader will load
> >>> which ever it encounters first.  (Maybe I will eat these words 
> latter?) ;-)
> >>>
> >> Hi John,
> >>
> >> The driving premise behind SLF4J is to reduce surprises. I think we
> >> should do things by the book and avoid duplication. Since SLF4J
> >> version 1.1, user's have been asked to have two jars, slfl4-api.jar in
> >> addition to a binding. In SLF4J 1.3, the general arrangement remains
> >> the same, except that slf4j-api is now self-sufficient as a
> >> compile-time dependency.
> >>
> >> I quite like this user-story. Alice and Bob expose slf4j-api as a
> >> transitive dependency, while Sally, the end-user, chooses to depend on
> >> a binding of her own selection.  We respond to Eric Crahen's initial
> >> request [1] without fundamentally changing how SLF4J works.
> >>
> >> I do not wish to hide behind backward-compatibility excuses. We
> >> finally have a nice and clear separation between slf4j-api and
> >> slf4j-binding. Let's keep it clean and simple even if it costs an
> >> extra jar on the class path.
> >>
> >> [1]
> >> http://www.qos.ch/pipermail/logback-user/2007-February/000129.html
> >>
> >>
> >>
> >>
> >>> a good weekend for you too,
> >>> John
> >>>
> >> --
> >> Ceki Gülcü
> >> Logback: The reliable, generic, fast and flexible logging framework 
> for Java.
> >> http://logback.qos.ch
> >>
> >> _______________________________________________
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> >> dev at slf4j.org
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> >>
> >
> >
>
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-- 
Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.
http://logback.qos.ch