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Re: '#' exit document space? (was: Documents, Cars, Hills, and Valleys)

From: Tim Berners-Lee <timbl@w3.org>
Date: Thu, 11 Apr 2002 08:16:49 -0400
Message-ID: <034d01c1e152$c21860f0$ac01a8c0@CREST>
To: "Graham Klyne" <GK@ninebynine.org>
Cc: <www-rdf-interest@w3.org>

----- Original Message -----
From: "Graham Klyne" <GK@ninebynine.org>
To: "Tim Berners-Lee" <timbl@w3.org>
Cc: <www-rdf-interest@w3.org>
Sent: Thursday, April 11, 2002 4:04 AM
Subject: '#' exit document space? (was: Documents, Cars, Hills, and Valleys)


> At 06:22 PM 4/10/02 -0400, Tim Berners-Lee wrote:
> >The semantic web must model HTTP faithfully.
> >
> >The solution of course is very simple, because the # allows us
> >to jump from documents to things through the mime type.
> >We just invent a new language, not a new protocol. This cost is
> >much smaller.
> >
> >Because even a semantic web which talks about Mark and his cars
> >is still doing it with documents, and the document way of working
> >is still useful, and the hTTP machinery for talking about the
> >properties of the documents themselves is important.
> >
> >Given that the # allows us to be free of any restriction, we avoid
forcing
> >HTTP to be what it ain't and still get all we need.
>
> This seems to be putting an awful burden of responsibility on one
> character, something I had seen as a small syntactic device...


The # is a huge syntactic device -- because the document identifier
on the left is so different and the whateveritis on the right are
so different, defined by different specs.  The former hands off
immeditely to the protocol spec, the later to the format spec.

> It seems, reading your comments, that one SHOULD NOT use a bare HTTP URL
to
> identify, say, an XML namespace because that is not a document.  I suppose
> it has a certain elegance, because the document:
>
>      http://www.w3.org/1999/02/22-rdf-syntax-ns
>
> can be viewed as describing the namespace:
>
>      http://www.w3.org/1999/02/22-rdf-syntax-ns#
>
> which seems to be how things work out in practice (for RDF, at least).

Well, when there is a one-one correspndence between two things, the ID
of one can be used to identify the other.  So we could just say that
the namespace is identified by giving the URI of the namespace document.

The big hole we have is the way RDF makes URIrefs by attaching localnames,
which is not shared.  Indeed, xml schema can't give you the URIref
for an element type for example.

> But I'm concerned that this represents a changing from widely understood
> principles, and will be difficult to deploy consistently (in people's
minds
> and in software).
>
> #g
>
>
> -------------------
> Graham Klyne
> <GK@NineByNine.org>
>
Received on Thursday, 11 April 2002 08:16:45 GMT

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