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

RE: HTTP Endpoints and Resources

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 26 Sep 2007 11:56:50 -0500
Message-Id: <p06230901c32039ee7db2@[]>
To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>
Cc: "Rhys Lewis" <rhys@volantis.com>, "Technical Architecture Group WG" <www-tag@w3.org>

>I like your recognition that 200 and 303 URIs have something in common,
>but please don't refer to the 303 case has having an "http endpoint"
>that "responds", because doing so would introduce the unnecessary
>confusion of having the same URI denote two different things: an "http
>endpoint" and the thing the URI was intended to denote -- a person, for
No. This is confused because of the now venerable confusion, which 
continuously dogs all these discussions, between "identifying" in the 
sense of providing a functional Web-mediated connection to something, 
and referring to an object, aka denoting it. These are (forgive the 
shout) NOT THE SAME THING. Please don't get them confused. A name can 
denote without being attached (like all names off the Web) and it can 
be attached without denoting. This awful word "identifies" sometimes 
means one thing, sometimes another; but the two concepts are 
distinct. The fact that a URI provides access to something (a 
resource? I neither know nor care) which performs some meaningful 
action (such as a 303 redirect) does NOT imply that the URI, 
considered as a referring name, must therefore denote that thing 
(resource?). These two relationships, of accessing and naming, are 
COMPLETELY DISTINCT. Now, the TAG is suggesting, and I agree that 
this makes good sense, that *in the case where the accessed resource 
emits a 200 response* (and perhaps in similar cases for other xxTPs, 
i.e. where the access works 'normally'), then we should all agree 
that the accessing URI does indeed denote the resource: but this is a 
*convention* we are being asked to adopt, not a fact of nature or an 
architectural requirement. And this convention does not say ANYTHING 
about the relationship between denotation and access in other cases: 
nor should it, indeed, because there is nothing to be said in those 
cases. If you get a 404 error or if you get a 303 redirect, you can 
infer NOTHING AT ALL about what, if anything, the URI denotes.

>What the 200 and 303 cases have in common is that the server's response
>indicates that the URI owner has associated the URI with a resource,
>i.e., the URI owner has "minted" or "allocated" the URI.  (Slight
>digression: hence the server's response can be viewed as "declaring"[3]
>that URI.)  But in both cases it is the *server* that sends back the
>response -- not the URI.  When the response is 200 we may colloquially
>speak of "the URI responding", and this sloppiness in language is
>harmless in that case because the URI denotes the resource that is
>(conceptually) "responding".  But when the URI denotes a person, and the
>response is 303, it is *not* the person that is conceptually responding.
>Hence, the sloppiness of talking about "the URI responding" becomes
>quite misleading.

But nobody said that the URI responded. In the 200 case, what 
responds is the resource Web-attached to, and denoted by (assuming 
the above-mentioned convention) the URI. In the 303 case, what 
initially responds is the thingie (resource?) which is Web-attached 
to the URI - which the URI accesses - but which (might but more 
probably) might not be denoted by it. In the 404 case, all bets are 

BTW, I don't think calling any of these a 'declaration' helps in any 
way at all, and if anything is only going to make things more 

Pat Hayes

>3. URI declarations: http://dbooth.org/2007/uri-decl/
>David Booth, Ph.D.
>HP Software
>+1 617 629 8881 office  |  dbooth@hp.com
>Opinions expressed herein are those of the author and do not represent
>the official views of HP unless explicitly stated otherwise.

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
Received on Wednesday, 26 September 2007 16:57:08 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 15:32:53 UTC