W3C home > Mailing lists > Public > www-xml-linking-comments@w3.org > July to September 2006

RE: fragment identifiers and media types (was RE:XPointerconsidered incomprehensible)

From: Dan Connolly <connolly@w3.org>
Date: Wed, 06 Sep 2006 15:56:03 -0500
To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>
Cc: simonstl@simonstl.com, noah_mendelsohn@us.ibm.com, Bjoern Hoehrmann <derhoermi@gmx.net>, www-tag@w3.org, www-xml-linking-comments@w3.org, Jonathan Marsh <jmarsh@microsoft.com>
Message-Id: <1157576163.9288.1175.camel@dirk>

On Wed, 2006-09-06 at 15:47 -0400, Booth, David (HP Software - Boston)
wrote:
> > From: Dan Connolly [mailto:connolly@w3.org] 
> > 
> > On Wed, 2006-09-06 at 13:59 -0400, Booth, David (HP Software - Boston)
> > wrote:
> > > . . .
> > > Protocol messages may be used in the process of determining
> > > the meaning, but there is a difference between the meaning
> > > being determined by the content of the retrieved message
> > > versus the mere fact of retrieval. In determining the meaning
> > > of http://simonstl.com/#news , if a GET on
> > > http://simonstl.com/ returns a 200 OK and an HTML document, the mere
> > > fact of retrieval indicates that http://simonstl.com/#news
> > > identifies a location within an HTML document. It therefore
> > > cannot, for example, identify a person or a dog.
> >
> > So don't publish an HTML document there if you want to use it
> > to identify a Dog.
> 
> That was my point!  Hash URIs are more restrictive than slash URIs with
> 303-redirects because the meaning of a hash URI depends on the media
> type.  I.e., they are interdependent.  Slash URIs with 303-redirects do
> not have this limitation: you can serve any media type *independent* of
> the kind of resource that you wish to identify.  

OK, I see your point now. I see it more of a limitation of HTML
(that I hope to fix) than a limitation of hash URIs.


> From a design perspective, this difference is significant.  If you are
> minting a new URI to identify something other than an "information
> resource"[], it doesn't make any logical sense to tie the meaning of
> that URI to the current media type of your documentation.  At some point
> in the future, you may wish to serve your documentation using some new
> or different media types.  (As the WebArch says, new media types are "a
> means by which the Web can grow"[2].)  And as this thread has
> illustrated, the question of whether the meaning would remain
> "sufficiently consistent"[2] across media types is not at all obvious.

On balance, I still find # URIs a lot more straightforward than
redirects.

> [2] WebArch section 3.2.2 on Fragment identifiers and content
> negotiation:
> http://www.w3.org/TR/webarch/#frag-coneg
> 
> David Booth
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Wednesday, 6 September 2006 20:56:13 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 27 October 2009 08:39:46 GMT