Distributed co-operating processes and transactions

As part of our research in the Archons [Jensen 82] project on decentralized computers, we have developed a relational model of data consistency to replace the conventional serialization model for reasoning about the relationships among distributed system data objects in general and state variables in particular, We not only permit but encourage such relationships to be probabilistic, in the interest of efficiency. This model leads to a new formulation of co-operating processes, and thence to the notion ol cooperating transactions: co-operating processes whose actions are made atomic for the sake of reliability. We believe that cooperating processes are valuable in a computer network, but essential in a decentralized computer [Jensen 82] where the conceptually singular but physically dispersed global operating system requires a transaction facility in the kernel [Jensen 80], These ideas are illustrated by examples from our initial experience in applying the model to the Accent network operating system and other system software of the Spice personal computing network. This document is intended to be an overview of the synchronization effort in the Archons project, and future publications will elaborate on many of the individual points touched on here.