Channel-Less Process Communication

A channel is an abstract data structure which allows for passing messages from one process to another one. We propose several variants of OCCAM, a minimalistic programming language in which a program consists only of processes and channels. The variants differ in how channels are accessed by processes. We prove that all these variants are equally expressive, i.e. an arbitrary OCCAM program can be simulated in any of the variants and the other way around. A particularly interesting variant is to assign exactly one channel to each parallel process. This makes the concept of channels redundant provided that the parallel processes are named. The simulation techniques can be applied to a variety of abstract models and practical systems.