Distributed OSGi Greeter Demo Walkthrough

This is a walkthrough of the Distributed OSGi Greeter Demo. It should help users of the Distributed OSGi get started with it.

The greeter demo can be found in the samples/greeter directory and implements a simple OSGi Greeter Service and a consumer to that service with a trivial UI.

The Greeter demo design

The demo is composed of 3 bundles:

• The Greeter Interface bundle
• The Greeter Service Implementation bundle
• The Greeter Service Consumer bundle
  The Greeter Interface bundle exports the GreeterService interface which both other bundles depend on. This is the interface:

  public interface GreeterService {
      Map<GreetingPhrase, String> greetMe(String name) throws GreeterException;
  }

  The GreetingPhase and GreeterException classes are also defined by this bundle.

The Greeter Service bundle provides a trivial implementation of the GreeterService interface. Additionally, it has an Activator:

public class Activator implements BundleActivator {
    private ServiceRegistration registration;

    public void start(BundleContext bc) throws Exception {
        Dictionary props = new Hashtable();

        props.put("osgi.remote.interfaces", "*");
        props.put("osgi.remote.configuration.type", "pojo");
        props.put("osgi.remote.configuration.pojo.address", "http://localhost:9090/greeter");
        
        registration = bc.registerService(GreeterService.class.getName(), new GreeterServiceImpl(), props);
    }

    public void stop(BundleContext bc) throws Exception {
        registration.unregister();
    }
}

Besides creating the service instance, the activator sets the additional properties on the service that are required to make it available remotely:

• The osgi.remote.interfaces property is set to '*', which means that all the interfaces passes to registerService are good for remoting. In this case it's just the GreeterService interface.
• The osgi.remote.configuration.type is set to pojo, which is a CXF specific configuration type that can be used to set the URL at which the service is to be exposed. This is done via the osgi.remote.configuration.pojo.address property.