Java – Apache Felix: What are extension bundles


Apache Felix has the concept of an "extension bundle". This seems to be a bundle that contributes to the system bundle. There is also a special URL "felix://extensions/" being registered for them.

When would I need to use extensions as opposed to regular bundles?

Are there examples of bundles that use this approach?

Is this a Felix-only feature or part of the OSGi spec?

Best Solution

according to the felix Implement extension bundles issue, extension bundles are described in section 3.15 of the OSGi R4 specification - so it is part of the OSGi spec. both that issue and the spec answers your question about when to use them. for examples, i would check google.