import org.helgoboss.domino.DominoActivator
import org.osgi.service.http.HttpService

class MyService(httpService: HttpService)

class Activator extends DominoActivator {
  whenBundleActive {
    // Make service available as long as another 
    // service is present
    whenServicePresent[HttpService] { httpService =>
      val myService = new MyService(httpService)
      myService.providesService[MyService]
    }
  }
}

import org.helgoboss.domino.DominoActivator

class KeyService(key: String)

class Activator extends DominoActivator {
  whenBundleActive {
    // Reregister service whenever configuration changes
    whenConfigurationActive("my_service") { conf =>
      val key = conf.getOrElse("key", "defaultKey")
      new KeyService(key).providesService[KeyService]
    }
  }
}