Learning lifecycle - OSGi in Action - page 116

A BundleActivator is how a bundle hooks into the lifecycle layer to become
lifecycle aware, which allows it to gain access to all framework facilities for
inspecting and modifying the framework state at execution time.

■

The framework associates a lifecycle state with each installed bundle, and the
BundleContext and Bundle lifecycle interfaces make it possible to transition
bundles though these states at execution time.

■

Monitoring bundle lifecycle events is a form of dynamic extensibility available
in the OSG i framework based on the dynamically changing installed set of bun-
dles (also known as the extender pattern).

■

The lifecycle and module layers have a close relationship, which is witnessed
when bundles are updated and uninstalled. You use the Package Admin Service
to manage this interaction.

■

Now we'll move on to the next layer of the OSG i framework: the service layer. Services
promote interface-based programming among bundles and provide another form of
dynamic extensibility.