Subject: (new) ARK Persistent Identifier Scheme

From: "John A. Kunze" <[email-masked]>
Date: Tue, 13 Mar 2001 10:28:47 -0500

I wanted to let folks know about a new persistent naming scheme called
ARK (Archival Resource Key).  It may be of interest to members of this
list.

A first version of the ARK proposal appears as an Internet-Draft in the
IETF archives, but the revision pointed to by

     http://www.ckm.ucsf.edu/people/jak/home/ark-01.ps   (postscript, 26pp)
or
     http://www.ckm.ucsf.edu/people/jak/home/ark-01.txt  (plain text, 38pp)

is much more complete.  No part of the proposal is on the IETF meeting
agenda.  If any of you will be there (Minneapolis) next week, you should
be able to find me at the informal FURI (Future of Uniform Resource
Identifiers) session Tuesday 20 March, 17:00-18:00.

Enclosed is an abstract and table of contents.  There will no doubt be
a number of revisions to this draft proposal.  Comments and reactions
would be most welcome.  Please send them to [email-masked].

-John

---------------------------------------------------------------------------
John A. Kunze                  +1 415-502-6660    University of California,
530 Parnassus Ave, Box 0840    [email-masked]   San Francisco/US National
San Francisco, CA  94143-0840  Fax: 415-502-0910     Library of Medicine
----------------------- UC San Francisco and US NLM -----------------------

         The ARK Persistent Identifier Scheme  --  8 March 2001

Abstract

   The ARK (Archival Resource Key) is a scheme intended to facilitate
   the persistent naming and retrieval of information objects.  It
   comprises an identifier syntax and three services.  An ARK has four
   components:

                  ark:[NMAH]/NAAN/Name

   the prefix "ark:", the (optional and mutable) Name Mapping Authority
   Hostport (NMAH, where "hostport" is a hostname followed optionally by
   a colon and port number), the Name Assigning Authority Number (NAAN),
   and the assigned Name.  The NAAN and Name together form the immutable
   persistent identifier for the object.

   An ARK request is an ARK to which is appended a service request
   beginning with a question mark.  Use of an ARK request proceeds in
   two steps.  First, the NMAH, if not specified, is discovered based on
   the NAAN.  Two methods for discovery are proposed:  one is file
   based, the other based on the DNS NAPTR record.  Second, the ARK
   request is submitted to the NMAH.  Three ARK services are defined,
   gaining access to:  (1) the object (or a sensible substitute), (2) a
   description of the object (metadata), and (3) a description of the
   commitment made by the NMA regarding the persistence of the object
   (policy).  These services are defined initially to use the HTTP
   protocol, given the World Wide Web's pre-eminence among Internet
   information retrieval systems.  When the NMAH is specified, the
   "ark:" prefix may be replaced with "http://", to produce a valid URL
   that can gain access to ARK services using an unmodified Web client.

Table of Contents     (page numbers refer to the plain text document)

   Status of this Document ........................................    1
   Abstract .......................................................    1
   1.  Introduction ...............................................    3
   1.1.  Three Reasons to Use ARKs ................................    3
   1.2.  Organizing Support for ARKs ..............................    4
   1.3.  A Definition of Identifier ...............................    5
   2.  ARK Anatomy ................................................    6
   2.1.  The Name Mapping Authority Hostport (NMAH) ...............    6
   2.2.  The Name Assigning Authority Number (NAAN) ...............    7
   2.3.  The Name Part ............................................    8
   2.4.  Lexical Equivalence ......................................    8
   2.5.  Naming Considerations ....................................    9
   3.  Assigners of ARKs ..........................................   11
   4.  Finding a Name Mapping Authority ...........................   11
   4.1.  Looking Up NMAHs in a Globally Accessible File ...........   13
   4.2.  Looking up NMAHs Distributed via DNS .....................   15
   5.  Generic ARK Service Definition .............................   16
   5.1.  Generic ARK Access Service (access, location) ............   17
   5.2.  Generic Policy Service (permanence, naming, etc.)  .......   17
   5.3.  Generic Description Service ..............................   18
   6.  Overview of the HTTP Key Mapping Protocol (HKMP) ...........   18
   7.  Overview of Electronic Resource Citations (ERCs) ...........   21
   7.1.  ERC Syntax ...............................................   23
   7.2.  ERC Stories ..............................................   24
   7.3.  The ERC Anchoring Story ..................................   25
   7.4.  ERC Elements .............................................   26
   7.5.  ERC Element Values .......................................   29
   7.6.  ERC Element Encoding and Dates ...........................   31
   7.7.  ERC Stub Records and Internal Support ....................   33
   8.  Advice to Web Clients ......................................   33
   9.  Security Considerations ....................................   34
   10.  Authors' Addresses ........................................   34
   11.  References ................................................   35
   12.  Appendix:  An NLM Prototype ARK Service ...................   36
   13.  Appendix:  Current ARK Name Authority Table ...............   36
   14.  Copyright Notice ..........................................   38