IN DISTRIBUTED APPLICATIONS, THERE MAY BE partial failures of the network or of components on the network. Leasing is a way for components to register that they are alive , but to ensure that they are "timed out" if they fail or are unreachable. Leasing is the mechanism used between applications to give access to resources over a period of time in an agreed manner.
Leases are requested for periods of time, and these requests may be granted, modified, or denied . The most common example of a lease is when a service is registered with lookup services. A lookup service will not want to keep a service forever, because it may disappear. Keeping information about nonexistent services is a waste of resources on the lookup service and also may lead to clients wasting time trying to access services that aren't there. As a result, a lookup service will grant a lease saying that it will only keep information for a certain period of time, and the service can renew the lease later if it wants to.