The Amenetet Monitoring Service monitors remote services which register with it, heart beats are used in both directions to monitor the health of remote services. Remote services maintain a lease with Amentet and renew that lease regularly. Amentet then pings back to the remote service to monitor its health.
Remote Services can monitor multiple objects internally, when "pinged" by Amentet, if any of these objects has disappeared an exception is thrown back with the list of missing objects...