The CIM Event Model

An event is an occurrence, something that happens. In programming terms, an event is an occurrence in a computer system to which an application might need to respond, for example, opening a dialog box in response to a mouse click on a GUI. A CIM event is a change in an occurrence of interest in a managed environment.

The CIM event model, a framework for handling CIM events, conforms to the Common Information Model (CIM) Indications Specification, published by the Desktop Management Task Force (DMTF). The CIM event model distinguishes between an event and the notification of that event (an indication). In CIM, events are not published; indications are published.

CIM events can be classified as intrinsic or extrinsic. An intrinsic event is a built-in CIM event that occurs in response to changes to data in which a namespace, class, or class instance is created, modified, or deleted. An extrinsic event is a user-defined event that is not already described by an intrinsic events.

Currently, only intrinsic events for creating, modifying, and deleting CIM instances are handled. The following classes are used to report intrinsic events:

• CIM_InstCreation — Indicates that a new instance was created.

• CIM_InstDeletion — Indicates that an existing instance was deleted.

• CIM_InstModification — Indicates that an instance was modified.

How Indications of Events are Generated

By default, the CIM Object Manager polls for indications of intrinsic events at regular intervals. Administrators can change the event polling interval and the default polling behavior of the CIM Object Manager by editing the properties in the cimom.properties file. For instructions on editing the cimom.properties file, see the Solaris WBEM Services Administrator's Guide.

The CIM Object Manager polls by enumerating instances, repeating the enumeration at the specified polling interval, and then finding any new, changed, or deleted instances between the two sets of enumerated instances. If a provider generates indications for events, the CIM Object Manager will not poll the provider. If possible, providers should generate indications for the intrinsic events that occur in the dynamic instances of the classes they support. This prevents the performance cost that results from the CIM Object Manager polling for the event.

The CIM Object Manager Repository generates an indication when a static instance is created, modified, or deleted.

How Subscriptions are Created

A client application can subscribe to be notified of CIM events. A subscription is a declaration of interest in one or more streams of indications. Currently, providers cannot subscribe for event indications.

An application that subscribes for indications of CIM events describes:

• Which events in which it is interested.

• What action the CIM Object Manager should take when the events occur.

The occurrence of an event is represented as an instance of one of the subclasses of the CIM_Indication class. An indication is generated only when a client subscribes for the event. If no provider delivers the event for which a client subscribes, the subscription will fail.