org.lsst.ccs.framework

Interface HasLifecycle

All Known Implementing Classes:

AgentMonitorService, AgentPeriodicTaskService, Alarm, AlertService, AlertService, CalcDevice, Channel, Control, DataProviderDictionaryService, Device, Line, Monitor, PersistencyService, RuntimeService

public interface HasLifecycle

Interface to implement for components that require to perform tasks at specific times of the enclosing Subsystem life cycle. There are four main phases: - build: dedicated to building the subsystem. Nodes can be added to the ComponentLookup during this phase. - init: in which components are initialized. Components can expect to have been set in a safe configuration and hardware can now be initialized and connections to the devices can be opened - start: the subsystem has just joined the buses. Any status publication can happen at this point - shutdown: the subsystem is shutting down. All hardware connections should be terminated at this point. There are two methods for each phase: phase() and postPhase(). The phase() method is invoked while traversing the ComponentLookup tree going up, from parent to children, while the postPhast() method is invoked traversing the ComponentLookup tree going down, once it has been invoked on all the children. So the following rules apply: - the phase() method is invoked on a node after it has been invoked on its parent and before it is invoked on any of its children - the postPhase() method is invoked on a node after it has been invoked on all its children and before it is invoked on its parent. - the order in which these methods are invoked among nodes at the same level (siblings) depends on the order in which the nodes were added to the ComponentLookup tree.

Author:

The LSST CCS Team

Method Summary

Modifier and Type	Method and Description
default void	build() First lifecycle hook.
default void	init() Called from the enclosing Subsystem at initialization phase.
default void	postBuild() First lifecycle hook.
default void	postInit() Called from the enclosing Subsystem at construction phase.
default void	postShutdown() Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called after shtudownNow has been invoked on all the children.
default void	postStart() Called from the enclosing Subsystem after HardwareController components have been handled.
default void	shutdown() Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called.
default void	start() Called from the enclosing Subsystem when Agent.startAgent() has been called.

Method Detail

build

default void build()

First lifecycle hook. Modification of the component tree is allowed at this stage. After this stage the tree of component cannot be modified anymore. This is where agent periodic tasks should be scheduled.

postBuild

default void postBuild()

First lifecycle hook. Modification of the component tree is allowed at this stage. After this stage the tree of component cannot be modified anymore. This is where agent periodic tasks should be scheduled.

init

default void init()

Called from the enclosing Subsystem at initialization phase.

This method is called before the children components of this object have their init method called.

At the time it is called, connection to the messaging layer is not yet done, so there should be no attempt to send messages in the body of this method. Configuration for message listening can nevertheless be done here, such as adding MessageListener objects.

It is unnecessary to call super.init()

postInit

default void postInit()

Called from the enclosing Subsystem at construction phase. This method is called after init and postInit have been called on this component's children.

start

default void start()

Called from the enclosing Subsystem when Agent.startAgent() has been called. At the time it is called :

• the PhaseState is INITIALIZING
• connection with the messaging layer is effective, the enclosing subsystem has started StatusHeartBeat publication
• the startup configuration has been loaded (if provided). IMPORTANT NOTE : This statement will not be true in future releases. Code that expect the startup configuration to be loaded should be moved from start to postStart.

It is unnecessary to call super.start()

postStart

default void postStart()

Called from the enclosing Subsystem after HardwareController components have been handled. At the time it is called :

• HardwareController components have been handled without throwing HardwareException

If successful, the enclosing subsystem's PhaseState will change to OPERATIONAL and the subsystem will invoke startTicking on its modules components.

If an HardwareException is thrown, the OperationalState will change to ENGINEERING_FAULT until a call to completeInitialization is successful

It is unnecessary to call super.postStart()

shutdown

default void shutdown()

Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called. At the time it is called :

• PhaseState is CLOSING.
• HardwareController.checkStopped() has been called

It should be overridden to free non hardware related resources.

postShutdown

default void postShutdown()

Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called after shtudownNow has been invoked on all the children. At the time it is called :

• PhaseState is CLOSING.
• HardwareController.checkStopped() has been called

It should be overridden to free non hardware related resources.