org.osgi.framework
Interface ServiceFactory

All Known Implementing Classes:

XMLParserActivator

public interface ServiceFactory

Allows services to provide customized service objects in the OSGi environment.

When registering a service, a ServiceFactory object can be used instead of a service object, so that the bundle developer can gain control of the specific service object granted to a bundle that is using the service.

When this happens, the BundleContext.getService(ServiceReference) method calls the ServiceFactory.getService method to create a service object specifically for the requesting bundle. The service object returned by the ServiceFactory is cached by the Framework until the bundle releases its use of the service.

When the bundle's use count for the service equals zero (including the bundle stopping or the service being unregistered), the ServiceFactory.ungetService method is called.

ServiceFactory objects are only used by the Framework and are not made available to other bundles in the OSGi environment. The Framework may concurrently call a ServiceFactory.

See Also:

BundleContext.getService(org.osgi.framework.ServiceReference)

ThreadSafe

Method Summary

java.lang.Object	getService(Bundle bundle, ServiceRegistration registration) Creates a new service object.
void	ungetService(Bundle bundle, ServiceRegistration registration, java.lang.Object service) Releases a service object.

Method Detail

getService

public java.lang.Object getService(Bundle bundle,
                                   ServiceRegistration registration)

Creates a new service object.

The Framework invokes this method the first time the specified bundle requests a service object using the BundleContext.getService(ServiceReference) method. The service factory can then return a specific service object for each bundle.

The Framework caches the value returned (unless it is null), and will return the same service object on any future call to BundleContext.getService from the same bundle.

The Framework will check if the returned service object is an instance of all the classes named when the service was registered. If not, then null is returned to the bundle.

Parameters:

bundle - The bundle using the service.

registration - The ServiceRegistration object for the service.

Returns:

A service object that must be an instance of all the classes named when the service was registered.

See Also:

BundleContext.getService(org.osgi.framework.ServiceReference)

ungetService

public void ungetService(Bundle bundle,
                         ServiceRegistration registration,
                         java.lang.Object service)

Releases a service object.

The Framework invokes this method when a service has been released by a bundle. The service object may then be destroyed.

Parameters:

bundle - The bundle releasing the service.

registration - The ServiceRegistration object for the service.

service - The service object returned by a previous call to the ServiceFactory.getService method.

See Also:

BundleContext.ungetService(org.osgi.framework.ServiceReference)