The Vsync software library is a BSD-licensed open source library written in C# for the .NET platform, providing a wide variety of primitives for fault-tolerant distributed computing, including: state machine replication, virtual synchrony process groups, atomic broadcast with several levels of ordering and durability, a distributed lock manager, persistent replicated data, a distributed key-value store (also called a Distributed Hash Table or DHT), and scalable aggregation. The system implements the virtual synchrony execution model, and includes an implementation of Leslie Lamport's Paxos Protocol.
The main author is Ken Birman, a Professor of Computer Science at Cornell University, and it is the fourth in a series of Cornell-developed software libraries for reliable multicast. The first was the Isis Toolkit, developed in 1985 and ultimately used in the New York Stock Exchange, the French Air Traffic Control System, the US Navy AEGIS and other settings.
Vsync was originally released as Isis2 in 2010, but Birman changed the name of the package in order to avoid similarity of the name to ISIL. The name Vsync is a reference to the formal model used by the system, namely virtual synchrony.
- Ken Birman (2010). "A history of the virtual synchrony replication model. In Replication, Bernadette Charron-Bost, Fernando Pedone, and André Schiper (Eds.). Springer-Verlag, Berlin, Heidelberg 91-120" (PDF).
- Robbert Van Renesse, Silvio Maffeis and Ken Birman (April 1996). "Horus: A Flexible Group Communications System". Communications of the ACM. 39 (4): 76–83.
- Xiaoming Liu; Christoph Kreitz; Robbert van Renesse; Jason Hickey; Mark Hayden; Ken Birman & Robert Constable. (December 1999). "Building Reliable, High-Performance Communication Systems from Components. In Proc. of the 17th ACM Symposium on Operating System Principles, Kiawah Island Resort, SC" (PDF).