Events and Event Management

EVM provides a centralized means of posting, distributing, storing, and reviewing event information. These features are supported regardless of the event channel used by individual event posters, and without requiring the existing posters to change how they interact with their current channels. EVM makes event information easily accessible to the system administrators. It also provides a flexible infrastructure that can be used as an event distribution channel by the following:

The mechanism used to pass event information is called event notification, and the component generating the event is known as the event poster. The EVM event-posting mechanism is a one-way communication channel. It enables the poster to communicate information to any entity that accesses it. The poster need not know which entities, if any, are interested in accessing an event that is posted.

An entity that expresses an interest in receiving event information is called an event subscriber. Depending on the type of event, subscribers can include system administrators, other software components, or ordinary users. Some events are never be subscribed to.

Events can be posted and subscribed to by any process, and the same process can be both a poster and a subscriber. However, in all cases, the ability to post and access specific events is governed by security authorizations.

In the simplest case, an event channel is a static ASCII log file containing event information from a single source, which a user can view by means of standard UNIX tools (for example, more).

EVM provides a single point of focus for multiple event channels by combining events from all sources into a single event stream. Interested parties can either monitor the combined stream in real time or view historical events retrieved from storage. The EVM viewing facilities include a full set of command-line utilities, which enable the events to be filtered, sorted, and formatted in a variety of ways. You can also configure EVM to perform automatic notification of selected conditions.

	NOTE: EVM is a facility for broadcasting messages and must not be used to implement a private point-to-point communication channel between two processes. Using EVM for such purposes can impact the system performance negatively. To establish communication with another process and send the information that is not relevant to the system administrators, HP recommends that you use a more direct channel, for example, use sockets or pipes communication channel.

Figure 1-1 provides an overview of posting, subscribing, and retrieval operations.

Figure 1-1 EVM Overview