report: URN Architecture Meeting at University of Tennessee, Oct 30-31

Keith Moore (
Tue, 07 Nov 1995 18:04:32 -0500

Message-Id: <>
From: Keith Moore <>
Subject: report: URN Architecture Meeting at University of Tennessee, Oct 30-31
Date: Tue, 07 Nov 1995 18:04:32 -0500

On October 30-31, several proponents of various URN schemes met to discuss
ways to make progress on URNs.  This message contains a report of that
meeting, including a list of items for which there was general agreement,
a list of topics requiring further discussion, and outlining areas 
and assignments for additional work. 

A URN BOF has been scheduled for the Dallas IETF for further discussion 
of these topics.

As host of the meeting, I would like to express my appreciation to
the meeting attendees for their hard work, patience, and good will
in working out these agreements.

Keith Moore


URN Architecture Meeting

A workshop of representatives of announced URN schemes was held at the
University of Tennessee on Oct 30-31.  The objective was to identify
areas of convergence, areas  likely to benefit from focussed
discussion, and topics marked by deep divisions.  It is further hoped
that useful discussion documents will flow from this meeting that can
serve to focus discussion at the upcoming Dallas IETF.


Keith Moore       University of Tennessee
Reed Wade         University of Tennessee 
Michel Mealling   Georgia Tech
Ron Daniel        Los Alamos National Laboratory 
David Ely         CNRI
Patrik Falstrom   Bunyip Information Systems, Inc.
Stuart Weibel     OCLC
Dan Laliberte     NCSA
Michael Shapiro   NCSA

1. Syntax of URNs

   The URN consists of three parts: a prefix string, a naming
   authority, and a local unique identifier.  There will be a 
   visible separator between the naming authority and the
   local unique identifier.

   Canonical proposed URN syntax: 
         URN:  identifies the namespace
         NA    a hierarchical top-level-first slash-delimited name of the
               authority who assigns the name. For the purposes of a 
               generalized Internet specific lookup mechanism this name 
               should, through some transformation algorithm, be a valid 
               DNS name. 
         :     designated separator between naming authority and
               the LUI     
	 LUI   a locally unique identifier of unspecified syntax or
	       structure. The LUI is optional so that the naming
	       authority itself can be identified.


2.  New DNS record type 

    It is desirable to define one or more new DNS resource record types
    (tentatively called NAPTR records) that define mappings from 
    the "NA" portion of a URN to resolution servers for that URN.  
    The new resource records will allow listing of multiple resolution
    servers and protocols.

3.  Basic resolution strategy:

    Transform the NA portion of the URN into traditional domain name
    syntax, and query DNS for any NAPTR records listed under that domain.

    Any fallback strategies to be used (if no resource records are found) 
    are for future discussion.

4. New TLD (probably .URN)

   It is judged desirable to promote the introduction of a new
   top-level domain in DNS for the restricted purpose of URN resolution
   and to ensure/promote the longevity of the names assigned under this

   This domain would operate under slightly different rules:
     - reassignment is prohibited
     - other rules to be determined

   Assignment of URNs is not  contingent on use of this namespace
   It is intended to  be a resolution specific, longevity-oriented
   part of the DNS name space.

Open Issues for future discussions

  Fallback Mechanisms for DNS lookup

     -what happens if there are no NAPTR records?

  Shorthand notation for URN: redundancy

  Detailed URN Syntax
  International character sets

  Specification of NAPTR Records

  Rules for new Top level domain 

  How are resolution request services specified?   

Committee assignments:

  NAPTR record structure

  URN Syntax and shortcut
      Daniel and Weibel

  Fallback mechanisms: justification and mechanisms
      LaLiberte and Moore   

  Rules for new TLD

      Falstrom, Weibel and Moore

  Service requests

    LaLiberte Weibel Moore Daniel

    Probably two dimensions of service requests:
      a.) Resource record encoded services
	  the availability of services available for a naming authority
	  might be recorded in resource records
          may be a core set of such services which can be defined
          in advance.
      b.) Document Link service requests
          there needs to be a way to invoke services by specification
          within a document.