Distributed Systems Based Upon a Functional Communication Model with a Timed Token Protocol

Abstract The paper investigates communication in distributed systems with a non­ homogeneous architecture. Such systems consist of a large number of user nodes(workstations) and a smaller number of server nodes (computational servers, file servers, printer servers. etc.). In the framework of the functional communication model, we propose a token passing scheme which allows both server initiated com­munication andcommunication initiatedby the users. A timed token protocol is used to control the two access modes, the scheduled access and the nonscheduled one. 1. OVERVIEW OFFUNCTIONALCOMMUNICATION Communication plays a central role inthe designofany distributed system. Commoncom-munication models are centered around the conceptofmoving data from one node ofa networkto another. An alternative communication model based upon the concept ofmoving computa-lions from one node to another in a network. is possible. In the following, we call the later afunctional communication model. Its chiefidea is thatcommunication occurs only in connectionwitha requestforservice.The duality of the two modes seems obvious; the Remote Procedure Call protocols arecommonly implemented using the data movement paradigm. On the other hand, data can bemoved ina functional communication model. eitherby regarding itas a resultofa request for ser-vice or as input data fromlto the remote server.