OSGi: passing parameters to a specific bundle

Question

I have a custom jar with a custom Main class, which starts the OSGi Framework and installs/starts the bundles. This main jar also includes a properties file.

Goal: I have a bundle A which should pick up the properties of this properties file of the main jar somehow.

My first attempt was to define a component in bundle A (using Apache Felix SCR/ Declarative Services) and retrieve the properties in its activate-method. This works so far that I'm getting the default value specified in the @Property-annotation.

But how can I now pass the properties of the properties file to this component?

Passing arguments to OSGi application mentions to use the Config Admin, but how can I use this in the Main class?

• The Config Admin is in a bundle, not in the main jar, and the bundles are not installed in any specific order
• The Main class doesn't know anything about the bundles it installs, let alone a specific service.pid.

Update:

I'm trying now an approach suggested by @vizier (which doesn't use Config Admin and thus doesn't have the mentioned issues):

• define a service interface in the main jar (system bundle)
• provide an implementation, which reads the property file (the properties file is in the same jar)
• export the package X containing this service interface
• bundle A then can import the package X and e.g. reference the service using Declarative Services

But in my bundle A I'm getting:

org.osgi.framework.BundleException: Unresolved constraint in bundle <bundle A> [14]: Unable to resolve 14.0: missing requirement [14.0] osgi.wiring.package; (&(osgi.wiring.package=<package X>)(version>=0.1.0)(!(version>=1.0.0)))
    at org.apache.felix.framework.Felix.resolveBundleRevision(Felix.java:3826)
    at org.apache.felix.framework.Felix.startBundle(Felix.java:1868)
    at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1191)
    at org.apache.felix.framework.FrameworkStartLevelImpl.run(FrameworkStartLevelImpl.java:295)
    at java.lang.Thread.run(Thread.java:722)

Does the system bundle only export osgi packages even if some custom packages were added to Export-Package in the Manifest file? Or what is going wrong?

Answer 1

As always, register a service ... The receive bundle (and any other bundle) can search for the service and read the properties. Since you're the framework launcher you can register any service you want through the Framework object you get from the Launching API.

In bnd(tools) I have a launcher. It uses the OSGi Launcher API to create the bundle, similar to what you describe. I pass the command line arguments as properties on a Launcher service. Look at https://github.com/bndtools/bnd/blob/master/biz.aQute.launcher/src/aQute/launcher/Launcher.java for an example.

You can of course also just get the Configuration Admin service through the Framework object and use it to register Configurations. It is quite easy (just actually done it) to define the configurations in JSON (or, dare I say it, XML) file and then read it and update Configuration Admin.