W3C home > Mailing lists > Public > www-archive@w3.org > September 2002

Re: URNs versus URLs for identifiers

From: Joseph Reagle <reagle@w3.org>
Date: Tue, 17 Sep 2002 15:58:53 -0400
To: Dave Remy <DaveR@geotrust.com>
Cc: www-archive@w3.org
Message-Id: <200209171558.53463.reagle@w3.org>

On Tuesday 17 September 2002 02:39 pm, Dave Remy wrote:
>  Anyway, I am
> curious why URLs were used for identifiers instead of URNs in the XML Sig
> specification.  I notice in some of the early drafts URNs were used.

This is common practice at W3C because many of us feel that:
1. It is very useful to be able to dereference a URL (and perhaps get a 
schema or some other definition).
2. URLs are cheap, you don't have to worry about registration processes, nor 
cluttering a registry with early or test identifiers. Many folks that use 
URNs do this by *avoiding* registering their URNs at the start, and even at 
the end of their work. If you use URLs, everyone can define and experiment 
much more organically.
3. By using a URL one is explicitly recognizing that the answer to the 
question about URI stability is social/institutional.  The W3C commits to 
maintaining persistent URLs as identifiers, and so should others.

You might want to review:
  http://www.w3.org/TR/2002/WD-webarch-20020830/#identifiers
  http://www.w3.org/DesignIssues/Axioms.html
  http://www.w3.org/Consortium/Persistence
  http://www.w3.org/1999/10/nsuri

In terms of trends, much to my chagrin, QNames are hapharzdly being used by 
W3C WGs as identifiers now:
  http://www.w3.org/2001/tag/doc/qnameids
Received on Tuesday, 17 September 2002 15:58:55 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 7 November 2012 14:17:22 GMT