org.lsst.ccs.framework

Interface ClearAlertHandler

All Superinterfaces:

AlertHandler

public interface ClearAlertHandler
extends AlertHandler

Interface to be implemented by all classes that handle Alert clearing. Objects on the Agent ComponentLookup that implement this interface are automatically registered as clear alert handlers. Multiple handlers can be registered for a given Agent. ClearAlertHandlers will be called back with the instance of the Alert to be cleared and its AlertState. The handler has to assess if it is ok to clear the given Alert by first deciding if the given Alert can be cleared by the handler. When clearing an Alert instance the handlers will be called in order and depending on the return code the following actions will be taken:

• UNKNOWN_ALERT: this handler does not recognize the alert. The framework will move the the next handler.
• CLEAR_ALERT: it is ok to clear the alert. The framework will clear the alert if no other handler vetos the clearing.
• DONT_CLEAR_ALERT: the Alert is still valid and it should not be cleared. The framework will not clear the alert and stop looping over the registered handlers.

ClearedAlertHandlers are called only when the AlertState of the given Alert is not NOMINAL. Alerts in NOMINAL state are always cleared by the framework without involving ClearedAlertHandlers. When an Alert is not in NOMINAL state, all the handlers will be invoked and if the all return code UNKNOWN_ALERT, the framework will proceed to clear the Alert.

Author:

The LSST CCS Team

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ClearAlertHandler.ClearAlertCode Enumeration of codes returned when the canClearAlert method is invoked.

Method Summary

Modifier and Type	Method and Description
default ClearAlertHandler.ClearAlertCode	canClearAlert(Alert alert, AlertState alertState) Callback to clear an Alert instance.

Method Detail

canClearAlert

default ClearAlertHandler.ClearAlertCode canClearAlert(Alert alert,
                                                       AlertState alertState)

Callback to clear an Alert instance. Return a ClearAlertCode for the provided Alert.

Parameters:

alert - The Alert instance to clear.

alertState - The AlertState for the provided Alert.

Returns:

A ClearAlertCode to indicate which action is to be taken by the framework.