Sparse time versus dense time in distributed real-time systems

The restriction of the significant event occurrences, i.e., the sending and receiving of messages in a distributed real-time system, to the lattice points of a globally synchronized space/time lattice are discussed. One dimension of this space/time lattice represents the progression of time, the other dimension denotes the computational processes in the system. It is shown that this additional constraint simplifies solutions to agreement problems. After an analysis of the interdependence among temporal order, causal order, receive order, and the limits of time measurement in a distributed real-time system, criteria for the selection of the lattice points of this space/time lattice are presented