A migration framework provides for the migration of services in a cluster.
A migratable target contains a list of servers in the cluster capable of
hosting a migratable service. A migration manager can migrate the service
between servers in the migratable target, and can activate an instance of
the service on the selected host server. The migration manager ensures
that only one active instance of the service exists in the cluster. A
service stub can serve a user request on servers in the migration target,
such as by order of preference, until the user request is served on the
server hosting the active instance. A lease manager can assign a lease
period to determine how long a server hosts an active instance.This
description is not intended to be a complete description of, or limit the
scope of, the invention. Other features, aspects, and objects of the
invention can be obtained from a review of the specification, the
figures, and the claims.