The CEMon service is responsible for providing information coming from the Computing Element (CE).

The ``default information'' the CEMon service is able to provide is related to the CE itself: this information is represented according to the Glue Schema (1.1 and 1.2 version).

Other existing CEMon sensors that can be plugged into CEMon include the one publishing GridICE information, the one publishing CREAM job status information, the one publishing CE information according the needs of the ReSS OSG project (see Existing CEMon sensors to see the details of the existing sensors).

By implementing specific sensors, the CEMon service can also be configured to collect and provide other information types.

It is possible to interact with the CEMon service in a synchronous way (i.e. the client queries the CEMon service to get the required info) or asynchronously (i.e. the client can subscribe to get asynchronous notifications coming from theCEMon service). Moreover the CEMon administrator can configure predefined subscriptions, so the specified clients are automatically notified with asynchronous events, without the need of an explicit subscription.

Specific policies and specific actions can be set on CEMon subscriptions. For example if is possible to define a subscriptions so that the client is notified only when certain conditions are satisfied (e.g. when the CE queue is empty or the number of enqueued jobs is less than a certain value).