Question

How do I convert an existing jar file into an OSGi bundle?

Answer, Resolution

Here's a very simple way of turning an existing jar file in an OSGi bundle, while keeping control on exported packages.

The example creates an OSGi bundle from the attached junit-4.4.jar.

Note: The method below only works in a scenario where the jar file has no dependencies on other external jar files.

  1. Start by creating a the jar's manifest file:
    Manifest-Version: 1.0
    Created-By: myself
    Bundle-ManifestVersion: 2
    Bundle-Name: JUnit 4.4 bundle
    Bundle-Description: Package junit 4.4 in an OSGi bundle
    Bundle-Version: 4.4.0
    Bundle-ClassPath: .,junit-4.4.jar
    Bundle-SymbolicName: org.junit.framework
    Export-Package: junit.framework,junit.extensions,org.junit.runner,org.junit,junit.textui
    

    • Bundle-ClassPath header is set to allow embedding the original jar as is. Make sure its value matches the filename of the jar that you are going to embed in the bundle.
    • Export-Package is a list of packages contained in the jar that you would like to make available to other bundles running in the OSGi Container.
  2. Jar file
    Get the jar file, in our case from http://mirrors.ibiblio.org/pub/mirrors/maven2/junit/junit/4.4/junit-4.4.jar
  3. Create the bundle jar file by running the following command:
    jar cvfm junit-4.4-bundle.jar manifest.txt junit-4.4.jar 
    

    Where manifest.txt is the name of the manifest file created above.

    That's it - the resulting jar file (attached to this page as an example) is an OSGi bundle the exports the packages listed in Export-Package above, using the classes of the embedded junit-4.4.jar.

Applies To

All OSGi Containers

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