Virtual Time and Global States of Distributed Systems

A distributed system can be characterized by the fact that the global state is distributed and that a common time base does not exist. However, the notion of time is an important concept in every day life of our decentralized "real world" and helps to solve problems like getting a consistent population census or determining the potential causality between events. We argue that a linearly ordered structure of time is not (always) adequate for distributed systems and propose a generalized non-standardmodel of time which consists of vectors of clocks. These clock-vectors arepartially orderedand form a lattice. By using timestamps and a simple clock update mechanism the structure of causality is…