RFC 83 (rfc83) - Page 1 of 13

Language-machine for data reconfiguration

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Network Working Group                                        R. Anderson
Request for Comments: 83                                      A. Harslem
NIC: 5621                                                     J. Heafner
                                                                    RAND
                                                        18 December 1970


               LANGUAGE-MACHINE FOR DATA RECONFIGURATION

Introduction

   In NWG/RFC #80 we mentioned the needs for data reconfiguration along
   with a complier/executor version of a Form Machine to perform those
   manipulations.

   This note proposes a different approach to the Form Machine.
   Specifically, we describe a syntax-driven interpreter that operates
   on a grammar which is an ordered set of replacement rules.  Following
   the interpreter description are some "real-world" examples of
   required data reconfigurations that must occur between RAND consoles
   and the Remote Job System on the UCLA 360/91.  Lastly, we suggest
   that the Protocol Manager mentioned in NWG/RFC #80 can be simplified
   by using the Form Machine and two system forms (specified a priori in
   the code).

   Caveat:  The Form Machine is not intended to be a general purpose
   programming language.  Note the absence of declaration statements,
   etc.

THE FORM MACHINE

I.  Forms

   A form is an ordered set of rules.

      F = {R1, ...,Rn}

   The first rule (R1) is the rule of highest priority; the last rule
   (Rn) is the rule of lowest priority.

   The form machine gets as input: 1) a list of addresses and lengths
   that delimit the input stream(s); 2) a list of addresses and lengths
   that delimit the output area(s); 3) a pointer to a list of form(s);
   4) a pointer to the starting position of the input stream; and 5) a
   pointer to the starting position of the output area.  The Form
   Machine applies a form to the input string emitting an output string
   in the output area.  The form is applied in the following manner:




Anderson, et. al.
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