How to use

org.apache.stanbol.enhancer.servicesapi.impl.EnginesTracker

constructor

public AllActiveEnginesChain(BundleContext context, String name) {
  if(context == null){
    throw new IllegalArgumentException("The parsed BundleContext MUST NOT be NULL!");
  }
  if(name == null || name.isEmpty()){
    throw new IllegalArgumentException("The parsed Chain name MUST NOT be NULL!");
  }
  this.context = context;
  this.name = name;
  Set<String> trackAll = Collections.emptySet();
  this.tracker = new EnginesTracker(context, 
    trackAll, //empty set to track all engines
    this);
  this.tracker.open();
}
  

@Activate
protected void activate(ComponentContext ctx) {
  final BundleContext bc = ctx.getBundleContext();
  engineTracker = new EnginesTracker(bc, Collections.<String>emptySet(), 
    new ServiceTrackerCustomizer() {
      
      @Override
      public Object addingService(ServiceReference reference) {
        Object service = bc.getService(reference);
        if(service != null){
          _enginesCache = null; //rebuild the cache on the next call
        }
        return service;
      }
      @Override
      public void modifiedService(ServiceReference reference, Object service) {
        _enginesCache = null; //rebuild the cache on the next call
      }
      @Override
      public void removedService(ServiceReference reference, Object service) {
        if(reference != null){
          bc.ungetService(reference);
          _enginesCache = null; //rebuild the cache on the next call
        }
      }
      
    });
  engineTracker.open();
}

@Activate
protected void activate(ComponentContext ctx) {
  final BundleContext bc = ctx.getBundleContext();
  engineTracker = new EnginesTracker(bc, Collections.<String>emptySet(), 
    new ServiceTrackerCustomizer() {
      
      @Override
      public Object addingService(ServiceReference reference) {
        Object service = bc.getService(reference);
        if(service != null){
          _enginesCache = null; //rebuild the cache on the next call
        }
        return service;
      }
      @Override
      public void modifiedService(ServiceReference reference, Object service) {
        _enginesCache = null; //rebuild the cache on the next call
      }
      @Override
      public void removedService(ServiceReference reference, Object service) {
        if(reference != null){
          bc.ungetService(reference);
          _enginesCache = null; //rebuild the cache on the next call
        }
      }
      
    });
  engineTracker.open();
}

tracker = new EnginesTracker(ctx.getBundleContext(), chain.keySet(),this);
tracker.open();