Component instances progress through four major lifecycle events: create, start, stop, and destroy.
Component instances may retain isolated persistent state on a storage medium while they are not running which helps them maintain the illusion of continuity across restarts.
When a component instance is created, the component frameworks assigns a unique identity to the instance, adds it to the component topology, and makes its capabilities available for other components to use.
Once created, a component instance can then be started or destroyed.
Starting a component instance loads and runs the component's program and provides it access to the capabilities that it requires.
Every component runs for a reason. The component framework only starts a component instance when it has work to do, such as when another component requests to use its instance's capabilities.
Once started, a component instance continues to run until it is stopped.
Stopping a component instance terminates the component's program but preserves its persistent state so that it can continue where it left off when subsequently restarted.
The component framework may stop a component instance for a variety of reasons, such as:
A component can implement a lifecycle handler to be notified of its impending termination and other events on a best effort basis. Note that a component can be terminated involuntarily and without notice in circumstances such as resource exhaustion, crashes, or power failure.
Once stopped, a component instance can then be restarted or destroyed.
Destroying a component instance permanently deletes all of its associated state and releases the system resources it consumed.
Once destroyed, a component instance ceases to exist and cannot be restarted. New instances of the same component can still be created but they will each have their own identity and state distinct from all prior instances.
