EMS Manual

Reporting Events
EMS Manual—426909-005
8-4
Task 1.2: Decide Which Reported Events Are
Critical or Action Events
need to be mounted or when printers run out of paper, but action events can be
appropriate for other subsystems in other circumstances as well.

Do not report an action event when only a specific user or process can resolve the
problem. Assume that EMS will route the message through a filter that selects
action events for ViewPoint to display for an operator. If an operator likely would
not have the information needed to respond to the action event, an action event is
not the appropriate mechanism for resolving the problem.
Action-event messages occur in pairs: an action-attention message informs the
operator of what needs to be done, and an action-completion message tells the
operator that the action situation has been resolved. A typical action-event scenario
might progress as:
1. A subsystem encounters a problem for which operator assistance is required. It
creates and sends an action-attention message that describes the situation and
includes:

An action-needed token with the value TRUE, which indicates that operator
action is required

An action-ID token, which helps to identify the event

As the subject of the event message, a token containing the name of the
resource that needs attention
The action-ID token, the subject token, subsystem ID, and system number are
all necessary to specify an action event uniquely.
2. ViewPoint retrieves the event message, through a filter that passes action events,
and displays the message for the operator.
3. The operator corrects the problem. The subsystem might be able to detect that the
problem was corrected. If it cannot, the operator must inform the subsystem
through the operator interface to that subsystem.
4. The subsystem creates an action-completion message, which contains:

An action-needed token (with the value FALSE this time)

The action-ID token (with the same value as in the corresponding action-
attention message)

The SUPPRESS-DISPLAY token with a value of TRUE

The name of the resource that was serviced as the subject of the event
message
5. The subsystem sends the message to EMS.
6. ViewPoint retrieves the action-completion message through its filter. It compares
the system number, subsystem ID, action-ID token, and subject with the
corresponding tokens in the action-attention messages currently outstanding and
dims the matching attention message on the operator display.