org.lsst.ccs.framework

Interface HardwareController

All Known Implementing Classes:

CalcDevice, Device

public interface HardwareController

Interface to implement for components that handle direct or indirect interaction with hardware. The methods of this interface, when overridden, will be invoked by the framework at specific times of its life cycle.

Note that these methods are invoked as part of a top to bottom tree walking of the components that make the modular structure of the enclosing subsystem.

Author:

bamade

Method Summary

Modifier and Type	Method and Description
default TreeWalkerDiag	checkHardware() Override to initiate interaction with the hardware.
default void	checkStopped() Override with specific code to stop the hardware.

Method Detail

checkHardware

default TreeWalkerDiag checkHardware()
                              throws HardwareException

Override to initiate interaction with the hardware. First interaction with low level hardware should take place in the body of this method. At the time it is called, the enclosing subsystem has connected to the messaging layer and is in PhaseState.INITIALIZING state.

If accessing the hardware is considered as having failed, this method should throw an HardwareException. This will interrupt the startup process and make the subsystem go to OperationalState.ENGINEERING_FAULT and stays in PhaseState.INITIALIZING. The startup process will be resumed with a call to org.lsst.ccs.Subsystem#completeInitialization() that will invoke HardwareController#checkStarted()

If this method is considered having succeeded, the state goes to OperationalState.ENGINEERING_OK and PhaseState.OPERATIONAL

Returns:

a TreeWalkerDiag indicating if this component has already performed hardware checking for its own components (HANDLING_CHILDREN) or if the framework should do it (GO)

Throws:

HardwareException - if any failure interacting with the hardware occurs. The exception is caught by the framework.

checkStopped

default void checkStopped()
                   throws HardwareException

Override with specific code to stop the hardware. It is invoked upon calls to org.lsst.ccs.Subsystem#shutdown() or org.lsst.ccs.Subsystem#stop(long). At the time it is called, the enclosing subsystem is in PhaseState.CLOSING phase

If a failure in stopping hardware is noticed, the implementation should throw an HardwareException. This will interrupt the shutdown process

If no HardwareException is thrown, the shutdown process will resume.

Throws:

HardwareException - if a failure occurs while stopping the hardware.