The BundleActivator and Advisor Classes

The support SAT provides for creating a Managed Service Factory is split between two classes:

ManagedServiceFactoryBundleActivator: This class is an abstract subclass of BaseBundleActivator and an implementer of OSGi's ManagedServiceFactory interface. The class registers an instance of itself with the OSGi framework as a ManagedServiceFactory.
- A bundle that wishes to be a ManagedServiceFactory creates its activator as a concrete subclass of this class.
- The ManagedServiceFactoryBundleActivator class implements getName() to return its fully qualified class name.
- The ManagedServiceFactoryBundleActivator class implements the updated(String, Dictionary) method and knows how to manage the objects created for each configuration.
- When called by ConfigurationAdmin the ManagedServiceFactoryBundleActivator class is capable of deciding whether the updated method requires the creation of a new object, or simply the updating of an existing object. For both the creation of a new object and the updating of an existing object, the ManagedServiceFactoryBundleActivator class delegates to its advisor, an implementation of the interface IManagedServiceFactoryAdvisor that concrete subclasses are expected to create.
- The ManagedServiceFactoryBundleActivator class implements deleted(String) by delegating to its advisor.
- Concrete subclasses of ManagedServiceFactoryBundleActivator are required to implement the method createAdvisor() that returns an instance of the IManagedServiceFactoryAdvisor interface. An abstract implementation of this interface is provided by the class BaseManagedServiceFactoryAdvisor.
BaseManagedServiceFactoryAdvisor: This class is an abstract implementation of the IManagedServiceFactoryAdvisor interface. Concrete subclasses must provide behavior for managing an object based on a configuration provided by ConfigurationAdmin.

The IManagedServiceFactoryAdvisor interface is as follows:

public interface IManagedServiceFactoryAdvisor {
  Object create(String, Dictionary, IBundleActivationManager);
  void createImportedServiceFilters(String, Dictionary, Dictionary, IBundleActivationManager);
  void destroy(String, Object, Dictionary, IBundleActivationManager);
  String[] getImportedServiceNames(String, Dictionary, Dictionary, IBundleActivationManager);
  String[] getOptionalImportedServiceNames(String, Dictionary, Dictionary, IBundleActivationManager);
  void handleAcquiredOptionalImportedService(String, Object, String, Object, IBundleActivationManager);
  void handleReleasedOptionalImportedService(String, Object, String, Object, IBundleActivationManager);
  Object update(String, Object, Dictionary, Dictionary, IBundleActivationManager);
  void validateConfiguration(String, Dictionary) throws ConfigurationException;
}

Due to the seemingly complicated nature of this interface, an example will be presented to help explain the IManagedServiceFactoryAdvisor API. The example is a variation of VendorService example used elsewhere in the SAT documentation.