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Posted to dev@felix.apache.org by David Bosschaert <da...@gmail.com> on 2009/10/19 13:37:53 UTC

[Karaf] Not importing the exported packages

Hi all,

I came across the following in a number of pom.xml files in the Karaf build
system:

<plugin>
  <groupId>org.apache.felix</groupId>
  <artifactId>maven-bundle-plugin</artifactId>
  <configuration>
    <instructions>
      <Bundle-SymbolicName>${pom.artifactId}</Bundle-SymbolicName>
      <Export-Package>
          ${pom.artifactId}*;version=${pom.version}
      </Export-Package>
      <Import-Package>
          !${pom.artifactId}*,
          ... more stuff ...
      </Import-Package>
    </instructions>
  </configuration>
</plugin>

So in the Import-Package section, the packages that exported by a the bundle
are explicitly not imported. I always thought that you should be doing the
opposite and always import what you are also exporting. See
http://www.osgi.org/blog/2007/04/importance-of-exporting-nd-importing.html

Thoughts anyone?

David

Re: [Karaf] Not importing the exported packages

Posted by Guillaume Nodet <gn...@gmail.com>.

Yeah, I do have thoughts about this thing.
The blog entry is really misleading.  Take a look at
http://felix.apache.org/site/apache-felix-osgi-faq.html#ApacheFelixOSGiFAQ-Shouldabundleimportitsownexportedpackages?
but imho, it's not sufficient either.
The main point is that only when you export an api where you may have
multiple implementations, you'd want to import the packages.  For a
library / implementation, you should not do that, as it causes lots of
problems when deploying multiple versions.

On Mon, Oct 19, 2009 at 13:37, David Bosschaert
<da...@gmail.com> wrote:
> Hi all,
>
> I came across the following in a number of pom.xml files in the Karaf build
> system:
>
> <plugin>
>  <groupId>org.apache.felix</groupId>
>  <artifactId>maven-bundle-plugin</artifactId>
>  <configuration>
>    <instructions>
>      <Bundle-SymbolicName>${pom.artifactId}</Bundle-SymbolicName>
>      <Export-Package>
>          ${pom.artifactId}*;version=${pom.version}
>      </Export-Package>
>      <Import-Package>
>          !${pom.artifactId}*,
>          ... more stuff ...
>      </Import-Package>
>    </instructions>
>  </configuration>
> </plugin>
>
> So in the Import-Package section, the packages that exported by a the bundle
> are explicitly not imported. I always thought that you should be doing the
> opposite and always import what you are also exporting. See
> http://www.osgi.org/blog/2007/04/importance-of-exporting-nd-importing.html
>
> Thoughts anyone?
>
> David
>

-- 
Cheers,
Guillaume Nodet
------------------------
Blog: http://gnodet.blogspot.com/
------------------------
Open Source SOA
http://fusesource.com