Peer-to-Peer Replication in WinFS

WinFS, Microsoft’s new application storage platform, incorporates a novel peer-to-peer, knowledge-driven, state-based replication protocol. The goal is to support diverse applications requiring replication for easy sharing, high availability, and offline access. The system was designed to scale from a handful of personal computing devices in a home environment to thousands of servers that are globally distributed. Like other weakly consistent replicated systems, the WinFS replication model allows update operations to be performed on any machine without locking. Updated data items are sent between replicas in a lazy fashion via a pair-wise synchronization protocol. The technical contributions of the protocol’s design include minimizing replication-specific state and efficiently propagating updates while allowing arbitrary synchronization topologies, detecting conflicting updates, supporting automatic conflict resolution, accommodating overlapping user communities, and guaranteeing eventual convergence.