Locating OSGi applications
You can use classes in the
org.apache.aries.blueprint package to extend
the OSGi application programming model; this third-party SPI is provided through the
blueprint-1.0 server feature. You must access OSGi application bundles in to apply
your extensions. In Liberty, OSGi
applications run as Subsystems. To locate an OSGi application you can create a
ServiceTracker in a user feature.
About this task
This topic describes how the developer of a user feature can locate running OSGi applications. This task is often required for user features that provide programming model extensions to OSGi applications. For example, a new user feature might provide such extensions by implementing a new bundle extender, often referred to as a container, or, more simply, by tracking and invoking services published from within certain OSGi applications.
Such user features must use
BundleContext of a particular running OSGi application
to create new
ServiceTracker instances. This
BundleContext can be obtained from
org.osgi.service.subsystem.Subsystem that is
associated with the OSGi application. The following procedure describes
how to obtain that SubSystem service.
To locate an OSGi application by creating a
ServiceTracker in a user feature, complete the following steps:
- Construct an
org.osgi.framework.Filterthat is targeted to the Subsystem that you want to locate.
- Create an
org.osgi.util.tracker.ServiceTrackerthat uses the Filter from step 1 to obtain the
org.osgi.service.subsystem.Subsystemservice that is associated with the OSGi application that you want to locate.This
Subsystemservice instance provides everything you require to work with the OSGi application.
ServiceTrackerin a user feature:
import org.osgi.framework.BundleContext; import org.osgi.service.subsystem.Subsystem; import org.osgi.util.tracker.ServiceTracker; import org.osgi.util.tracker.ServiceTrackerCustomizer;
BundleContextof one of the bundles of the user feature:
String SERVICE_FILTER = "(&(objectClass=org.osgi.service.subsystem.Subsystem) (subsystem.type=osgi.subsystem.application)(subsystem.symbolicName=my.app))" org.osgi.framework.Filter filter = ctx.createFilter(SERVICE_FILTER);
org.osgi.util.tracker.ServiceTracker<Subsystem, Subsystem> str = new ServiceTracker<Subsystem, Subsystem>(ctx, filter, null);
org.osgi.framework.Constants.OBJECTCLASS; org.osgi.service.subsystem.SubsystemConstants.SUBSYSTEM_SYMBOLICNAME_PROPERTY; org.osgi.service.subsystem.SubsystemConstants.SUBSYSTEM_TYPE_APPLICATION; org.osgi.service.subsystem.SubsystemConstants.SUBSYSTEM_TYPE_PROPERTY;