EMS Manual

Standard Events
EMS Manual—426909-005
9-21
Common-Standard Tokens That Subsystems
Provide
Event
Subject
marked by ZEMS-TKN-SUBJECT-MARK (ZSPI-TYP-MARK,U)
Identifies the objects that are most directly involved in the event. The token
following the token ZEMS-TKN-SUBJECT-MARK is the subject name.
The subject of the event could be a hardware component, such as a controller
or processor, or a software component, such as a process, a protocol layer, a
file, a network connection, a subdevice, a transaction thread, or any named
function provided by the subsystem.
An event can contain multiple subjects; that is, more than one object specified in
an event. An event can contain a group name as a subject. The group name
refers to a collection, or group, of objects. If multiple subjects or a group name is
used, all objects must be of the same type and have experienced the same
condition. Using multiple objects and group names in the subject minimizes the
number of events generated. Subsystem and application developers should
decide whether to use single subject, multiple subjects, group object, or any
combination of these in their events.
The event subject is provided as a parameter to EMSINIT (and
EMSADDSUBJECTS if there is more than one subject.) The EMS routines
insert these two tokens in the event message: ZEMS-TKN-SUBJECT-MARK, a
subject mark token followed by the subject token. EMSGET uses the subject
mark token when the management applications request the subject token using
the special token ZEMS-TKN-SUBJECT.
Certain requirements must be met for names in the event subject. Additional
criteria must be satisfied if the name is also a group name. For more details,
see Underlying Philosophy of Standard Events
on page 9-10.