A High-Level Framework for Network-Based Resource Sharing

The principal goal of all resource-sharing computer networks, including the now international ARPA Network (the ARPANET), is to usefully interconnect geographically distributed hardware, software, and human resources. Achieving this goal requires the design and implementation of various levels of support software within each constituent computer, and the specification of network-wide "protocols" (that is, conventions regarding the format and the relative timing of network messages) governing their interaction. This paper outlines an alternative to the approach that ARPANET system builders have been taking since work in this area began in 1970, and suggests a strategy for modeling distributed systems within any large computer network. The first section of this paper describes the prevailing ARPANET protocol strategy, which involves specifying a family of application-dependent protocols with a network-wide inter-process communication facility as their common foundation. In the second section, the application-independent command/response discipline that characterizes this protocol family is identified and its isolation as a separate protocol proposed. Such isolation would reduce the work of the applications programmer by allowing the software that implements the protocol to be factored out of each applications program and supplied as a single, installation-maintained module. The final section of this paper proposes an extensible model for this class of network interaction that in itself would even further encourage the use of network resources.