CIM indication concept

In CIM terminology, an indication is the representation of the occurrence of an event. For example, an event can be the unexpected termination of a program, or the modification of a property value of a CIM instance. There is not necessarily a one-to-one correspondence between events and indications. In particular, multiple indications can be generated for the same underlying event if multiple CIM client applications had subscribed for the event. An event can also occur without causing a related indication to be raised, for example if no subscription was made for the event.

z/OS supports additional indications for the CIM infrastructure. As an example, the Storage Management CIM providers can generate indications for the state change of channel paths, this way enabling CIM clients to support event-based monitoring to avoid polling the CIM server. A CIM client can subscribe for conditions, for example when a channel path goes offline. While the subscription is active, an according CIM indication provider monitors the resource(s) and notifies the CIM client whenever the condition becomes true.

The CIM indication support comprises the following steps:

• Defining an indication filter condition: This describes the event that you might want to be notified about, that is, when to send an indication
• Defining an indication listener: This describes how and where to send an indication
• Activating the subscription by associating a filter with a listener
• Consuming the indication once it is raised: The indication is sent to the indication listener, which decides how to react to the event

The CIM Event Model defines the CIM classes used for indication support. It defines the CIM indication class hierarchy that is used to model various types of events, and the CIM subscription mechanism.

Further readings:

• CIM Event Model White Paper, DSP0107, Document Version 2.1 June 10,2003, provided by the Distributed Management Task Force (DMTF), describes the CIM Event Model.
• Specification for CIM Operations over HTTP describes how the CIM server transmits CIM indications to the CIM listener.
• DMTF Indications Profile DSP1054 1.1 describes the behavior of CIM indication delivery.
• CIM indications describes CIM indication classes and the CIM subscription mechanism.