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https://issues.apache.org/jira/browse/STANBOL-774?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rupert Westenthaler updated STANBOL-774:
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Description:
Host Applications that do run Stanbol in an embedded OSGI environment need to
export all packages of used Interfaces (and all Classes used in those
Interfaces). This is required to ensure that the java Classes used by Stanbol
(running within the embedded OSGI environment) are the same as the one
available to the Host application (see [1] for details).
To use Apache Stanbol in such a scenario one must be more careful with OSGI
metadata in the Stanbol bundle manifests.
This Issue covers mainly two improvements:
1. Ensure that all exported (and internally used) packages are also imported.
Otherwise internal usage of non-imported packages would case incompatibilities
with the host application as it could not cast instances created by using the
internal Classes to the Classes loaded by the Host applications Classloader
(see [2] for details).
2. Ensure that Stanbol bundles use proper version ranges for imported packages.
The Host Application is limited to a single version of a Class. So if different
Stanbol Bundles do require different versions of a module those can not be
correctly exposed form the Host Application via the System Bundle - what would
make it impossible for a Host Application to use the affected Stanbol Modules
together. To avoid it is important do not import fixed version but rather to
use proper version ranges for imported packages.
[1]
http://felix.apache.org/site/apache-felix-framework-launching-and-embedding.html#ApacheFelixFrameworkLaunchingandEmbedding-hostserviceusage
[2]
http://felix.apache.org/site/apache-felix-osgi-faq.html#ApacheFelixOSGiFAQ-Shouldabundleimportitsownexportedpackages?
was:
Host Applications that do run Stanbol in an embedded OSGI environment need to
export all packages of used Interfaces (and all Classes used in those
Interfaces). This is required to ensure that the java Classes used by Stanbol
(running within the embedded OSGI environment) are the same as the one
available to the Host application (see [1] for details).
However Bundles that do not explicitly import packages they export will rather
user their internal version instead of the version exported by the Host
application causing the Class version to become incompatible (see [2] for
details).
[1]
http://felix.apache.org/site/apache-felix-framework-launching-and-embedding.html#ApacheFelixFrameworkLaunchingandEmbedding-hostserviceusage
[2]
http://felix.apache.org/site/apache-felix-osgi-faq.html#ApacheFelixOSGiFAQ-Shouldabundleimportitsownexportedpackages?
> Check Exported, Imported and Private Packages; use version ranges for Imports
> -----------------------------------------------------------------------------
>
> Key: STANBOL-774
> URL: https://issues.apache.org/jira/browse/STANBOL-774
> Project: Stanbol
> Issue Type: Sub-task
> Reporter: Rupert Westenthaler
>
> Host Applications that do run Stanbol in an embedded OSGI environment need to
> export all packages of used Interfaces (and all Classes used in those
> Interfaces). This is required to ensure that the java Classes used by Stanbol
> (running within the embedded OSGI environment) are the same as the one
> available to the Host application (see [1] for details).
> To use Apache Stanbol in such a scenario one must be more careful with OSGI
> metadata in the Stanbol bundle manifests.
> This Issue covers mainly two improvements:
> 1. Ensure that all exported (and internally used) packages are also imported.
> Otherwise internal usage of non-imported packages would case
> incompatibilities with the host application as it could not cast instances
> created by using the internal Classes to the Classes loaded by the Host
> applications Classloader (see [2] for details).
> 2. Ensure that Stanbol bundles use proper version ranges for imported
> packages. The Host Application is limited to a single version of a Class. So
> if different Stanbol Bundles do require different versions of a module those
> can not be correctly exposed form the Host Application via the System Bundle
> - what would make it impossible for a Host Application to use the affected
> Stanbol Modules together. To avoid it is important do not import fixed
> version but rather to use proper version ranges for imported packages.
> [1]
> http://felix.apache.org/site/apache-felix-framework-launching-and-embedding.html#ApacheFelixFrameworkLaunchingandEmbedding-hostserviceusage
> [2]
> http://felix.apache.org/site/apache-felix-osgi-faq.html#ApacheFelixOSGiFAQ-Shouldabundleimportitsownexportedpackages?
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