Logically instantaneous message passing in asynchronous distributed systems

Asynchrony (due to unknown message transmission delay) complicates the design of protocols for distributed systems. To simplify the protocol design task therefore, the authors propose an interprocess (point-to-point) communication mechanism that has the characteristic of instantaneous message passing. They first establish a hierarchy among synchronization properties, which shows that to ensure the logically instantaneous message passing property it is not always necessary to use a rendezvous mechanism. Next, they propose a solution to the logically instantaneous message passing problem that is more efficient than R. Bagrodia´s (1989) rendezvous and K.J. Goldman´s (1991) logically synchronous multicast in the point-to-point (single-cast) setting. This algorithm has the following properties: it is applicable without deadlock to the partner model in which each process acts as both client and server; it requires three control messages to send an application message, which is shown to be quasioptimum message complexity; and its worst-case response time from a send request to the occurrence of the corresponding send event is 2kΔ (sec.), where k is the maximum number of interfering send requests and Δ (sec.) is an assumed upper bound on interprocess communication delay. Furthermore, two modified algorithms are proposed: one for reducing the number of control messages required for an application message, and the other for attaining a shorter average response time by using a randomization technique