MonALISA Registration and Discovery
MonALISA services are able to discover each other in the distributed environment and to be discovered by the interested
clients. Each MonALISA service registers itself with a set of Lookup Services (LUSs) as part of one or more groups and it
publishes some attributes that describe itself. In this way any interested application can request MonALISA services based
on a set of matching attributes.
The registration uses a lease mechanism. If a service fails to renew its lease, it is removed from the LUSs and
a notification is sent to all the services or other application that subscribed for such events. Remote event notification
is used in this way to get a real overview of this dynamic system.
Lookup services have replicated information. It is important for the monitoring service to be registered in two or more
distributed lookup services, because if one fails responding, interested clients can find the MonALISA services registered
in the other online lookup services. Thus, the single point of failure problem can be avoided and a more reliable network
for registration of services can be achieved in the distributed environment. The JINI technology used allows dinamically adding
and removing Lookup Services from the system.
Securing the registration of services is important for LUSs not to be overloaded or damaged. MonALISA LUSs restrict the services'
registration based on an authorized X.509 certificate.
Figure 1: MonALISA Registration and Discovery Mechanism