Commentary on procedure calling as a network protocol (RFC0684)
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2019-Feb-14
Internet Society Requests For Comment (RFCs)
Issues in designing distributed computing systems. Shortcomings of RFC 674; see also RFCs 542 and 354.
Network Working Group RFC #684 NIC #32252 April 15,1975
A Commentary on Procedure Calling as a Network Protocol
This RFC is being issued as a first step in an attempt to stimulate a dialog on some issues in designing a distributed computing system. In particular, it considers the approach taken in a design set forth in RFC #674, commonly known as the "Procedure Call Protocol" (PCP). In the present document, the concentration is on what we believe to be the shortcomings of such a design approach.
Note at the outset that this is not the first time we are providing a critical commentary on PCP. During the earlier PCP design stages, we met with the PCP designers for a brief period, and suggested several changes, many of which became part of PCP Version 2. We hasten to add, however, that the nature of those suggestions stem from an entirely different point of view than those presented here. Our original suggestions, and also some subsequent ones, were mainly addressing details of implementation. In this note the concern is more with the concepts underlying the PCP design than with the PCP implementation.
This note is being distributed because we feel that it raises certain issues which have not been adequately addressed yet. The PCP designers are to be congratulated for providing a detailed written description of their ideas, thereby creating a natural starting point for a discussion of distributed system design concepts. It is the intent of this note to stimulate an interaction among individuals involved with distributed computing, which could perhaps result in systems whose designs don’t preclude their use in projects other than the one for which they were originally conceived.
The ideas expressed in this RFC have benefited from numerous discussions with Bob Thomas, BBN-TENEX, who shares the point of view taken.
A COMMENTARY on PROCEDURE CALLING Page 2
While the Procedure Call Protocol (PCP) and its use within the National Software Works (NSW) context attacks many of the problems associated with integrating independent computing systems to handle a distributed computation, it is our feeling that its design contains flaws which should prevent its widespread use, and in our view, limit its overall utility. We are not voicing our objection to the use of PCP, in its current definition, as the base level implementation vehicle for the NSW project. It is already too late for any such objection, and PCP may, in fact, be very effective for the NSW implementation, since they are proceeding in parallel and have probably influenced each other. Rather, we are voicing an objection to the "PCP philosophy", in the hope of preventing this type of protocol from becoming the de-facto network standard for distributed computation, and in the hope of influencing the future direction of this and similar efforts.
Some of the objectionable aspects of PCP, it can be argued, are differences of individual p...