java - accessing command-line arguments from OSGi bundle

Question

I have an application that runs as a collection of OSGi bundles. I start it using a very small wrapper that embeds the Felix framework. The necessity of that wrapper irks me a little, as does the fact that it depends on Felix (whereas the application itself could run just as well in, say, Equinox), so I want to get rid of it, and use the default Felix launcher.

The only thing that the wrapper really does is passing the command line arguments into the launched OSGi framework, so that a bundle there can react upon them. Note that it does not actually parse the arguments, just pushes the String[] into my application.

Is there a standard way (or at least a Felix-standard way) to access command line parameters from a bundle, so that I can do away with the custom launcher?

Answer 1

If you use bnd(tools) you can use its launcher. It registers the command line arguments as a service property 'launcher.arguments'.

This works extremely well when you combine it with the bnd package command. This command takes a bnd project or a bndrun file describing the running environment (bundles, properties, framework) and turns into into a standalone main jar. So you develop and debug in bndtools and when you're happy you turn it into a single executable jar. Example:

@Component
public class MyApp {
   String[] args;

   @Activate
   void activate() { 
      System.out.println("Args: " + Arrays.toString(args));
   }

   @Reference(target="(launcher.arguments=*)")
   void args( Object object, Map<String,Object> map) {
       args = (String[]) map.get("launcher.arguments");
   }
}

To turn into an executable:

bnd package myapp.bnd
java -jar myapp.jar -a somearg *.file