Writing Monitors for the Event Monitoring Service (December 1999)

22 Chapter1

Understanding the Event Monitoring Service

EMS Framework Components

This section describes the EMS framework components.

The EMS API

The EMS API is the interface between the registrar, client applications,

target applications, and resource monitors as illustrated in Figure 1-1.

The EMS API is provided as part of the EMS product.

The EMS API manages these events:

• client to registrar communication puts clients in contact with the

appropriate monitor for discovery and registering monitor requests.

• registrar to monitor communication passes client requests to

appropriate monitor

• make comparisons between the current resource values and

pre-selected threshold values

• monitor to target application communication:

— sends events to conﬁgured targets (pre-existing targets or target

you create)

— sends notiﬁcations to target applications when the resource values

meet event criteria

For example, a target TCP application uses EMS API to translate

TCP messages into EMS objects. This enables the ﬁelds to be read.

The target application then reads the ﬁelds of the EMS objects.

The registrar

The registrar is a link between the client applications and the resource

monitors. It communicates with the resource monitors on behalf of the

client applications to retrieve information requested by the clients. The

registrar runs on the same system as the resource monitors. The

registrar is provided as part of the EMS product.

The registrar does not need to be running while a resource is being

monitored. The registrar provides clients an interface to the monitors,

starts the monitors on behalf of a client, and provides communication