The Spread Wide Area Group Communication System

Building a wide area group communication system is a challenge. This paper presents the design and protocols of the Spread wide area group communication system. Spread integrates two low-level protocols: one for local area networks called Ring, and one for the wide area network connecting them, called Hop. Spread decouples the dissemination and local reliability mechanisms from the global ordering and stability protocols. This allows many optimizations useful for wide area network settings. Spread is operational and publicly available on the Web.