W3C home > Mailing lists > Public > www-tag@w3.org > November 2002

RE: Determining what a URI identifies

From: Larry Masinter <LMM@acm.org>
Date: Mon, 4 Nov 2002 07:26:48 -0800
To: "'Paul Prescod'" <paul@prescod.net>
Cc: <www-tag@w3.org>
Message-ID: <001c01c28416$9bbd0c00$6ace8642@masinter>

 > A simpler design is:
> > 
> > What a URI determines is defined by the scheme. The definition
> > of a URI scheme must include a clear definition of what strings
> > that start with that scheme identify. URIs that start with
> > "http" identify resources that are accessed via the HTTP protocol,
> > using the simple meaning that
> >    http://host.example.org/path
> > identifies the network resource that one connects to speaking
> > the HTTP protocol to host "host.example.org" with path component
> > "/path".


> Please outline the concrete implications of your proposal. 
> What does it mean for xmlns, RDF, SAX feature URIs, BEEP
> profile URIs, etc.?

At least for xmlns, feature URIs and BEEP profile URIs,
these uses of strings that conform to URI syntax do not
use those strings as resource identifiers, but rather as
indicators of some other conceptual relation to the
resource actually identified by the URI. If you have
a namespace http://ns.example.org/fabulous , you can
have a web site 'ns.example.org' and a web page at
path '/fabuous'. The web page isn't the namespace,
since the namespace is an abstraction. If you're lucky,
the web page describes the namespace. There's no
defined URI scheme for namespaces, although 'tdb'
might do.

RDF is a different story (as you know from the private
conversation we've been having): RDF itself contains
no grounding, and an RDF assertion that uses a URI
could mean the actual resource identified, the thing
described by it, or something completely different. RDF
doesn't say, it's the application using RDF that needs
to specify how it is grounded. (In some ways this is
as with syntactic elements in XML that are 'anyURI';
whether the anyURI string is being used as a resource
identifier or an indicator of something that has a
different conceptual relationship to that resource
depends on the application.)

I'm uneasy about this part of RDF design, but I can
accept it.
Received on Monday, 4 November 2002 10:26:08 UTC

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