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From "Stephan Siano (JIRA)" <>
Subject [jira] [Commented] (ARIES-1108) Discuss a better user experience when dealing with service dependencies.
Date Thu, 29 Aug 2013 12:08:52 GMT


Stephan Siano commented on ARIES-1108:

>... I don't understand how Export-Service is working (but would like to) because it doesn't
work for me. 
> Presumably, something in your environment is parsing Export-Service and making the service
capability available to the system.

Well Export-Service is actually not doing anything (except somehow declaring that this bundle
is supposed to provide this service...) This is also the case in my equinox based environment.

I just had two implementations that were exporting a service, one DS based, where the maven-bundle-plugin
did not generate the Export-Service header and one blueprint based one where it did. It didn't
work with the first bundle but it did work with the second, so I (wrongly) believed that the
reason for that was the Export-Service header, because both bundles registered the service
in the OSGi registry and I didn't expect the resolver to evaluate blueprint service dependencies...
> Discuss a better user experience when dealing with service dependencies.
> ------------------------------------------------------------------------
>                 Key: ARIES-1108
>                 URL:
>             Project: Aries
>          Issue Type: Brainstorming
>          Components: Subsystem
>            Reporter: John Ross
> Currently, Aries Subsystems will compute service requirements and capabilities for Blueprint
bundles only. This can be particularly problematic for users with application subsystems having
bundles with service dependencies on non-blueprint bundles outside of their control. For example,
an application blueprint bundle with a service dependency on EventAdmin will fail to resolve
unless the EventAdmin implementation bundle advertises the service capability in some supported
way. To get around this, the user must either (1) turn the bundle into a blueprint bundle,
(2) add a Provide-Capability header to the bundle's manifest, or (3) provide their own bundle
with a Provide-Capability header advertising all of the services of interest.
> The following represents a non-exhaustive list of possibilities.
> (1) Engage bundle providers to include a Provide-Capability header advertising services.
This would be particularly helpful for standard OSGi services. Engage OSGi to make this a
requirement or best practice.
> (2) Update the maven bundle plugin to generate this header, as it currently does for
the Export-Service header.
> (3) Support Import-Service and Export-Service headers in Aries Subsystems. These headers
are already generated by the maven bundle plugin.
> (4) Support DS in Aries Subsystems.
> (5) Add some sort of service listener to Aries Subsystems that will ensure existing services
are available as "virtual capabilities" to resolving subsystems.
> Note that in Aries Subsystems 1.0.1-SNAPSHOT+, the ModelledResourceManager service, used
to compute service requirements and capabilities, is now optional. This means users can uninstall
(or not install) the org.apache.aries.application.modeller bundle in order to disable service

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