Dependency management with OSGi

Question

I want to develop a multi-module application according to OSGi specification. Let's assume that one of my modules uses Apache Commons Logging 1.1.1. Spring provides a bundled version of Apache Commons Logging 1.1.1 in their repository, so I can add the corresponding dependency in my POM.

If I install my bundle in Apache Felix for example, is it right that the dependency to Apache Commons Logging 1.1.1 will not be resolved until I install the bundle of Apache Commons Logging 1.1.1 as well? My bundle will try to import a package that hasn't been exported.

I don't really understand how dependency management works in the OSGi world. Should I install every bundle that my application needs? Also, I don't understand how it integrates with Maven?

Thanks in advance for your explanations

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EDIT: I've seen there is a subproject of Apache Felix called OBR that seems to facilitate bundles management (e.g. deployment). But, we already have a Maven architecture with local repositories, private repositories... How is OBR integrated to Maven?

Answer 1

If you want to use OSGi together with maven then I recommend Apache Karaf as a server which can use the Felix OSGi framework. The advantage is that you can install bundles directly from maven repositories using mvn: urls.

If you just use Apache Karaf with a maven repo then you have no transitive resolution at runtime. You have to install all bundles you need. What helps a lot is that karaf has the concept of features. So you can use the features as coarse grained building blocks. You can also create your own features where you refer to other features and bundles. This allows to install your whole app with one command.

Felix and Karaf also support OBR but you would have to create your own OBR Repo. There are currently no public OBR repos. The advantage of OBR is that it can resolve most of the transitive dependencies. The Karaf features even work together with OBR so you can just list some top level bundles in the feature and let OBR resolve the rest.

In practice I have good experiences with simple Karaf features without OBR. It is some manual work but less than you would expect and works quite well.