Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm
RFC 3402

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Network Working Group                                        M. Mealling
Request for Comments: 3402                                      Verisign
Obsoletes: 2915, 2168                                       October 2002
Category: Standards Track

               Dynamic Delegation Discovery System (DDDS)
                        Part Two: The Algorithm

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes the Dynamic Delegation Discovery System
   (DDDS) algorithm for applying dynamically retrieved string
   transformation rules to an application-unique string.  Well-formed
   transformation rules will reflect the delegation of management of
   information associated with the string.  This document is also part
   of a series that is completely specified in "Dynamic Delegation
   Discovery System (DDDS) Part One: The Comprehensive DDDS" (RFC 3401).
   It is very important to note that it is impossible to read and
   understand any document in this series without reading the others.

Mealling                    Standards Track                     [Page 1]
RFC 3402                  DDDS - The Algorithm              October 2002

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  The Algorithm  . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.1 Components of a Rule . . . . . . . . . . . . . . . . . . . . .  6
   3.2 Substitution Expression Syntax . . . . . . . . . . . . . . . .  6
   3.3 The Complete Algorithm . . . . . . . . . . . . . . . . . . . .  8
   4.  Specifying An Application  . . . . . . . . . . . . . . . . . .  9
   5.  Specifying A Database  . . . . . . . . . . . . . . . . . . . . 11
   6.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   6.1 An Automobile Parts Identification System  . . . . . . . . . . 12
   6.2 A Document Identification Service  . . . . . . . . . . . . . . 14
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
       References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 16
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 17

1. Introduction

   The Dynamic Delegation Discovery System (DDDS) is used to implement
   lazy binding of strings to data, in order to support dynamically
   configured delegation systems.  The DDDS functions by mapping some
   unique string to data stored within a DDDS Database by iteratively
   applying string transformation rules until a terminal condition is
   reached.

   This document describes the general DDDS algorithm, not any
   particular application or usage scenario.  The entire series of
   documents is specified in "Dynamic Delegation Discovery System (DDDS)
   Part One: The Comprehensive DDDS" (RFC 3401) [1].  It is very
   important to note that it is impossible to read and understand a
   single document in that series without reading the related documents.

   The DDDS's history is an evolution from work done by the Uniform
   Resource Name Working Group.  When Uniform Resource Names (URNs) [6]
   were originally formulated there was the desire to locate an
   authoritative server for a URN that (by design) contained no
   information about network locations.  A system was formulated that
   could use a database of rules that could be applied to a URN to find
   out information about specific chunks of syntax.  This system was
   originally called the Resolver Discovery Service (RDS) [7] and only
   applied to URNs.

Mealling                    Standards Track                     [Page 2]
RFC 3402                  DDDS - The Algorithm              October 2002

   Over time other systems began to apply this same algorithm and
   infrastructure to other, non-URN related, systems (see Section 6 for
   examples of other ways of using the DDDS).  This caused some of the
   underlying assumptions to change and need clarification.  These
   documents are an update of those original URN specifications in order
   to allow new applications and rule databases to be developed in a
   standardized manner.

   This document obsoletes RFC 2168 [11] and RFC 2915 [9] as well as
   updates RFC 2276 [7].

2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this