Maintaining Replicas in Unstructured P2P Systems

Replication is widely used in unstructured peer-to-peer systems to improve search or achieve availability. The authors identify and solve a subclass of replication problems where each object is associated with a maintainer node, and its replicas should only be available as long as its maintainer is part of the network. Such requirement can be found in various applications, e.g., when objects are directory lists, service lists, or subscriptions of a publish/subscribe system. They provide maintainers with proven guarantees on the number of replicas, in spite of network churn and crash failures.