An open system of distributed processing. In a distributed processing system the various cooperating processes that jointly make up the total activity may run on separate processing systems linked only by communications channels. In an open distributed system the components are physically separated and are linked by communications channels that use open systems standards for their interfaces and protocols, and the intercommunication between the processes is again in accordance with a (different) set of open systems standards. It is clear that there is still a long way to go before open distributed processing will be a commercial reality.