Patent ID: 7447940

Claim:
A method for providing singleton services in a cluster, the method comprising: providing in the cluster a plurality of machines that each run at least one server and a node manager; designating a first server to join the cluster to be a cluster master; designating one or more servers in the cluster to be migratable servers, wherein said one or more migratable servers perform a singleton service; periodically renewing a lease between the migratable servers and a database; determining by the cluster master which leases of the migratable servers have expired; wherein if a migratable server, running on a first machine, fails to renew its lease, the cluster master automatically migrates the migratable server onto a second machine by remotely invoking the node manager on the first machine, and if the cluster master cannot invoke the node manager on the first machine, then the cluster master invokes a different node manager on a different machine to migrate the migratable server from the first machine to the second machine whereby execution of the singleton service offered by the migratable server is ensured; and preventing the migratable server on the first machine that failed to renew its lease from rejoining the cluster.