public class Activator implements BundleActivator {

	static private Activator defaultInstance;
	private BundleContext bundleContext;

	// List any services here
	// private ServiceTracker myService;

	public Activator() {
		defaultInstance = this;
	}

	public static Activator getDefault() {
		return defaultInstance;
	}

	public void start(BundleContext context) throws Exception {
		bundleContext = context;
	}

	public void stop(BundleContext context) throws Exception {
		// Stop your services here
		// if (myService != null) {
		//	myService.close();
		//	myService = null;
		// }

		bundleContext = null;
	}

	// Notice that this method is -> ONLY <- available within the package
	BundleContext getBundleContext() {
		return bundleContext;
	}

	// Retrieve and start your service here, something like:
	// public MyService getMyService() {
	// 	if (myService == null) {
	// 		if (bundleContext == null)
	// 			return null;
	//		myService = new ServiceTracker(bundleContext, MyService.class.getName(), null);
	//		myService.open();
	//	}
	//	return (MyService) myService.getService();
	// }

}

    Activator activatorRef = Activator.getDefault();
    BundleContext bc = activatorRef.getBundleContext(); 

    String fwOSVersion = bc.getProperty(Constants.FRAMEWORK_OS_VERSION);