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Re: Using urn:publicid: for namespaces

From: Sean B. Palmer <sean@mysterylights.com>
Date: Sat, 11 Aug 2001 01:51:36 +0100
Message-ID: <015c01c12201$b24d3300$9fdd93c3@z5n9x1>
To: "Stephen Cranefield" <scranefield@infoscience.otago.ac.nz>, <www-rdf-interest@w3.org>
> I agree with the comments that have been made on this mailing
> list about the inappropriateness of using the http URL scheme
> for names - especially those representing RDF schemas.

That depends upon how you define "inappropriate". Clearly, URLs as
names *do* work, and there is a huge amount of practical evidence to
support that (i.e. however many RDF documents there are out there, the
majority of which use URLs as terms).

The only real problems come in when people don't understand URI
architecture, which is fair enough because many of the URI "axioms"
are poorly defined/debated. However, it should be clear that all URIs
are there to serve as identifiers, and that the particulars of each
URI scheme are determined by the implementations, and therefore the
context of their uses. I have no problems with redefining the scope a
little bit, and I don't see where others should either. The only
problem is that URLs were designed as addresses rather than names, and
so they use the DNS system which is 98% perfect for both the HTTP Web
and the Semantic Web, but odd considering that if we used tags/PTSs
etc., we could have 99.999% reliability.

> While proposed URL schemes such as tag and ark are
> promising, it would be nice if there was an existing scheme
> that RDF schema designers could use right now.

They can use tag right now. I don't see any reason why not to: the
document is close to RFC status, expect that the authors are away on

> This would be encoded as a URN according to IETF RFC 3151
> as follows:
>   urn:publicid:-:University+of+Otago:NONSGML+Tourism+
> ontology+v1.0:EN

The idea of separating out names and addresses baffles some people,
and compels others, and I think at the moment I'm somewhere in
between. I can see what people get at when they say that they want to
use a URN/Public Identifier, because SGML catalogues are quite useful,
but it really is possible to do the same thing with HTTP URLs, as long
as you can guarantee their persistence. You could quite easily go and
get a PURL [1] to achieve similar results.

URIs have a function to persist in contexts enough so that they can be
useful. The scope of the context in which they can serve as addresses
vs. identifiers often varies, but there is no particular reason for
one scheme to have an arbitrarily larger scope for persistence than
another: as Roy mentioned earlier, it's the implementations themselves
that decide that.

[1] http://purl.org/

Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Friday, 10 August 2001 21:03:34 UTC

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