How to AOP aspectj in OSGi with Apache Felix

Question

I'm currently working on an OSGi project. Without many experiences in AOP combined with OSGi, I would like to know how to best do AOP in an OSGi environment? We have implemented the AOP scenario to create a console that intercept the call to a bundle in order to store the elapsed time for each task started by this bundle. Today, this aspect has been deployed on a jboss container using the LoadTimeWeaver provided by aspectj (adding an agent to the jboss start script in order to instrument the jars in the container -javaagent:%APP_HOME%\application\lib\aspectjweaver-1.6.11.jar). I've read some articles about this problem, but did not find a solution that suits well for me. There is, for example, an Equinox Incubator project for AspectJ. But since I'm using Apache Felix and Bnd(tools) I want to avoid using something from Equinox. One requirement for the weaving process will be that it should be at load-time as well (a bundle for aspectj that instrument the method inside another bundle). Someone can share experiences with such a use case using AOP aspectj with OSGI Felix ?

Answer 1

Here is a working example of minimal felix aspectj setup

The basic pattern is:

1. register weaving hook on activation

   public class Activator implements BundleActivator {
      public void start(BundleContext context) throws Exception {
          AspectWeaver weaver = new AspectWeaver();
          servList.add(context.registerService(WeavingHook.class, weaver, null));
      }
   }
   

2. inject weaving definition context:

   public class AspectContext extends DefaultWeavingContext {
       @Override
       public List<Definition> getDefinitions(final ClassLoader loader, final WeavingAdaptor adaptor) {
           if (definitionList == null) {
               definitionList = AspectSupport.definitionList(loader, rootConfig);
           }
           return definitionList;
       }
   }
   

3. provide weaving hook implementation

   public class AspectWeaver implements WeavingHook {
     @Override
     public void weave(WovenClass woven) {
         String name = woven.getClassName();
         BundleWiring wiring = woven.getBundleWiring();
         ClassLoaderWeavingAdaptor adaptor = ensureAdaptor(wiring);
         final byte[] source = woven.getBytes();
         final byte[] target;
         // aspectj is single-threaded
         synchronized (adaptor) {
             target = adaptor.weaveClass(name, source);
         }
         woven.setBytes(target);
    }