W3C home > Mailing lists > Public > www-tag@w3.org > September 2007

RE: Some TAG review of "Cool URIs for the Semantic Web"

From: <noah_mendelsohn@us.ibm.com>
Date: Fri, 28 Sep 2007 09:35:23 -0400
To: "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>
Cc: "Dan Connolly" <connolly@w3.org>, "Pat Hayes" <phayes@ihmc.us>, "Susie Stephens" <susie.stephens@gmail.com>, "Tim Berners-Lee" <timbl@w3.org>, "Technical Architecture Group WG" <www-tag@w3.org>
Message-ID: <OF7339B8FB.6C0841EE-ON85257364.0049D3EA-85257364.004AA77A@lotus.com>

Stuart Williams writes:

> I mention this here because there seems to be a tendency in these 
> threads to offer a definition whereby "information resources" are 
> just those which in fact respond to an http request with a 200 
> response code - whereas the TAG definition was intended to be 
> broader - anything whose essential nature is information.

Yes.  My recollection is that there was a feeling among some TAG members 
that when you have an information resource, say a list of parts and 
prices, that can be faithfully conveyed in a message.  Therefore it is 
appropriate to use status code 200 which says "this is a representation of 
that price list".  Conversely, if the resource is "me" (I.e. the actual 
person with messy hair etc.), then any representation would in some 
fundamental sense necessarily be less faithful.  You could, for example, 
send a picture and say that it represented me, but the representation 
would be much more indirect.  So, we looked for ways of identifying the 
resources for which such faithful representation was possible, and wound 
up saying just that:  if faithful representation (in the sense just 
suggested) in a message is possible, then it's appropriate to consider the 
resource as a primary http-scheme resource (no # needed).

Of course, whether you have such a representation and are willing to serve 
it at any particular time is a different question, which is why Stuart is 
right:  information resources are not just those for which you do serve 
with 200, but those for which you could.

FWIW: I personally have never been as convinced as some other TAG members 
that the distinction is so important.  I wouldn't not have objected to 
saying "of course that picture represents Noah, albeit in a very limited 
way, so you can assign him an http URI with no # and serve it with 200". I 
think either rule could have worked, but by the time I got involved the 
community was already well down the road on the "no 200 if it isn't a 
'faithful' representation" path, and I think that's OK too.  Given that 
this is the intention, I still think that the approach taken in AWWW is 
reasonable.  The term "information resource" is of course clunky, but I 
think the intention is about right.

Noah


--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








"Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>
Sent by: www-tag-request@w3.org
09/28/2007 09:06 AM
 
        To:     "Pat Hayes" <phayes@ihmc.us>, "Dan Connolly" 
<connolly@w3.org>
        cc:     "Tim Berners-Lee" <timbl@w3.org>, "Technical Architecture 
Group WG" <www-tag@w3.org>, "Susie Stephens" <susie.stephens@gmail.com>, 
(bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        RE: Some TAG  review of "Cool URIs for the 
Semantic Web"



> -----Original Message-----
> From: www-tag-request@w3.org [mailto:www-tag-request@w3.org] 
> On Behalf Of Pat Hayes
> Sent: 27 September 2007 21:13
> To: Dan Connolly
> Cc: Tim Berners-Lee; Technical Architecture Group WG; Susie Stephens
> Subject: Re: Some TAG review of "Cool URIs for the Semantic Web"
> 

<snip/>

> Well, Im not entirely sure about HTTP endpoint either, 
> because Im not savvy enough with the Web-architecture details 
> to know if this is really appropriate: maybe its something 
> just the other side of the http endpoint, if that latter is 
> more like the server.  But the key point is that the 
> distinction has to do with whether it can be
> *accessed* by transfer protocols, rather than with the way it 
> can be encoded or represented. The essential characteristics 
> of a billboard can be conveyed in an image, but if the image 
> has never been digitized then its not an information resource 
> (yet). 

FWIW, the wording of the TAG/webarch defn of 'information resource'
arose during our meeting in Basel [1].

Earlier attempts to offer the term "Web resource"  for things that
respond with 200 and a representation [2] failed on ground which now
escape me.

The thing that I recall about the "essentail characteristics being
conveyable in a message" definition was that it was about the
*potential* of such conveyance rather that the actuality of it. The
notion was, IIRC, intended to be about some Shannoesque notion of
information content rather than the fact or otherwise of a 200 response
when using a particular transfer protocol. 

I mention this here because there seems to be a tendency in these
threads to offer a definition whereby "information resources" are just
those which in fact respond to an http request with a 200 response code
- whereas the TAG definition was intended to be broader - anything whose
essential nature is information.

So, wrt to the billboard poster that you mention above, the image on the
poster would 'fit' the definition whereas the poster itself might not -
having a mass, being made of some material that will deteriorate over a
few weeks;

Stuart
--
[1] http://www.w3.org/2001/tag/2004/10/05-07-tag#infores234
[2]
http://lists.w3.org/Archives/Public/public-webarch-comments/2004JulSep/0
086.html

<snip/>

> Pat
> 
> >
> >
> >--
> >Dan Connolly, W3C http://www.w3.org/People/Connolly/

> --
> ---------------------------------------------------------------------
> IHMC                           (850)434 8903 or (650)494 3973   home
> 40 South Alcaniz St.           (850)202 4416   office
> Pensacola                                              (850)202 4440 fax
> FL 32502                                               (850)291 0667 
cell
> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes

Stuart
--
Hewlett-Packard Limited registered Office: Cain Road, Bracknell, Berks
RG12 1HN
Registered No: 690597 England
Received on Friday, 28 September 2007 13:36:05 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 22:56:18 UTC