Compact UUIDs for Constrained Grammars
draft-taylor-uuid-ncname-01
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Dorian Taylor
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2021-01-17
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Network Working Group D. Taylor
Internet-Draft Independent
Updates: RFC4122 (if approved) 15 January 2021
Intended status: Informational
Expires: 19 July 2021
Compact UUIDs for Constrained Grammars
draft-taylor-uuid-ncname-01
Abstract
The Universally Unique Identifier is a suitable standard for, as the
name suggests, uniquely identifying entities in a symbol space large
enough that the identifiers do not collide. Many formal grammars,
however, are too restrictive to permit the use of UUIDs in their
canonical representation (described in RFC 4122 and elsewhere),
despite it being useful to do so. This document specifies an
alternative compact representation for UUIDs that preserves some
properties of the canonical form, with three encoding varietals, to
fit these more restrictive contexts.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 19 July 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
Taylor Expires 19 July 2021 [Page 1]
Internet-Draft Compact UUIDs for Constrained Grammars January 2021
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Motivation & Applications . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Detection Heuristic . . . . . . . . . . . . . . . . . . . 6
4.2. Equivalency . . . . . . . . . . . . . . . . . . . . . . . 7
5. Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Encoding Algorithm . . . . . . . . . . . . . . . . . . . 7
5.2. Decoding Algorithm . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Normative References . . . . . . . . . . . . . . . . . . . . 10
9. Informative References . . . . . . . . . . . . . . . . . . . 11
Appendix A. Samples . . . . . . . . . . . . . . . . . . . . . . 11
Appendix B. Implementations . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The formal grammar production "one or more letters or underscores
followed by zero or more letters, digits, or underscores" (denoted by
the regular expression "/^[A-Za-z_][0-9A-Za-z_]*$/") is ubiquitous in
computing. It is often used for identifiers, and for good reasons.
We may encounter some variations on this theme, like admitting
hyphens, dots, or Unicode alphanumerics. Some systems may impose
additional constraints, like case-sensitivity (or the lack of it),
explicit upper- or lower-case letters, or limits on identifier
length.
UUIDs are standardized 128-bit identifiers with many useful
properties, and there are many places where it would make sense to
use them, but their canonical representation, either with or without
the URN prefix (see RFC 4122 [RFC4122]) does not conform to the
constraint described above:
* UUIDs contain hyphens (and colons in the case of URNs),
* UUIDs potentially start with a digit,
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* UUIDs are potentially too long for the slot.
This leads to developers creating incompatible, ad-hoc solutions.
The goal of this specification is to address an ostensible need for a
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