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Re: Determining what a URI identifies

From: Jonathan Borden <jonathan@openhealth.org>
Date: Mon, 4 Nov 2002 23:20:04 -0500
Message-ID: <009a01c28482$9e4349a0$7c674544@ne.mediaone.net>
To: "Tim Berners-Lee" <timbl@w3.org>, "Mark Baker" <distobj@acm.org>, <www-tag@w3.org>
Cc: "Larry Masinter" <lmm@acm.org>

Tim Berners-Lee wrote:
>
> http://www.w3.org/Consortium  identifies a web page.
> The web page is about the consortium.

Certainly if you say so...

>
> > and
> > indeed a handful[1] of people use it this way.  But the vast majority[2]
> > use "http://www.w3.org" for that purpose, and no information returned
> > from a GET on the latter suggests that it isn't, so that isn't likely to
> > change unless the W3C takes action.
>
> Firstly you are confusing the identification of a document and the
> identfication of the
> subject of the document.  Secondly, you seem to thing that there should
only
> one
> "real" identifier for W3C or for a page about W3C., neither is which are
> true.
>
> The meaning of a URI is determined by the URI spec, as Larry says.
> That spec says you look in the IANA registry to find the spec for the
> scheme.
> The HTTP spec gives the authority through DNS to the domain owner.
> So the ownership model is true for HTTP web pages
> but only because the URI spec points indirectly to the HTTP spec.

The meaning of an HTTP URI per RFC 2616

[[
3.2.2 http URL
The "http" scheme is used to locate network resources via the HTTP protocol.
This section defines the scheme-specific syntax and semantics for http URLs.

http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]

If the port is empty or not given, port 80 is assumed. The semantics are
that the identified resource is located at the server listening for TCP
connections on that port of that host, and the Request-URI for the resource
is abs_path (section 5.1.2).
]]

Now it seems to say that HTTP URLs are used to locate "network resources"
... and that the identified resources is located at the server. If this is
intended to say that HTTP URLs are intended to exclusively identify
_documents_ this is an obfuscated way to say that. It doesn't plainly say
that HTTP URLs are intended to locate documents on the network.

A "network resource" would be *any* RFC 2396 resource which presents an
representation via the network -- that is alot closer to what Roy seems to
be saying about what an HTTP URI might identify. Nothing in RFC 2616 seems
to restrict the range of HTTP URIs to identify documents (certainly the
representations are documents).

>
> So when RDF talks about  <#joe> as having
> a contact:mailbox of  <mailto:joe@example.com>
> an RDF processor which is aware of the URI spec
> and the spec of mailto:  knows that the object
> is an email mailbox according to the email specs.
>
> (((This of course drives the RDF logicians crazy as there
> is no model theory of the email specs.  More generally,
> logicians are used to defining a self-consistent
> system in a vacuum and life in the big city^H^H^H^Hweb
> can be relatively frightening.)))

I don't think the problem is a lack of model theory in specific, rather
language which does not _plainly_ support your assertion that HTTP URIs
necessarily identify resources which are documents.
.

Jonathan
Received on Monday, 4 November 2002 23:39:31 GMT

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