The basic jobs of checks are described here.
Checks are done by the Shinken Enterprise daemon at regular intervals, as defined by the check interval and retry interval check definitions.
Scheduled service checks are run in parallel by the pollers.
Services that are checked can be in one of four different states:
Checks are performed by plugins, which can return a state of OK, WARNING, UNKNOWN, or CRITICAL. These plugin states directly translate to service states. For example, a plugin which returns a WARNING state will cause a service to have a WARNING state.
When Shinken Enterprise checks the status of services, it will be able to detect when a service changes between OK, WARNING, UNKNOWN, and CRITICAL states and take appropriate action. These state changes result in different state types (HARD or SOFT), which can trigger event handlers to be run and notifications to be sent out. Check state changes can also trigger on-demand host checks. Detecting and dealing with state changes is what Shinken Enterprise Enterprise is all about.
When check change state too frequently they are considered to be “flapping". Shinken Enterprise can detect when services start flapping, and can cancel notifications until flapping stops and the service's state stabilizes. More information on the flap detection logic can be found on the flapping page.