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Re: Model-specific identity for anon resources, and its representation: A new issue?

From: Sergey Melnik <melnik@db.stanford.edu>
Date: Fri, 15 Jun 2001 18:58:11 -0700
Message-ID: <3B2ABD33.FC9DEB35@db.stanford.edu>
To: Dan Brickley <danbri@w3.org>
CC: Aaron Swartz <aswartz@upclink.com>, jos.deroo.jd@belgium.agfa.com, Jan.Grant@bristol.ac.uk, w3c-rdfcore-wg@w3.org
Dan Brickley wrote:
> 
> On Fri, 15 Jun 2001, Aaron Swartz wrote:
> 
> > On Friday, June 15, 2001, at 06:10  PM, Sergey Melnik wrote:
> >
> > > I don't agree that anonymous nodes should be part of the abstract
> > > syntax, and would suggest to consider this issue when cleaning up the
> > > model.
> 
> I disagree: it is critically important to distinguish between well known,
> public URI names for things and ad-hoc generated placeholder IDs that have
> been dreamt up by an RDF/XML parser. Unless the abstract syntax (or
> whatever we call it) maintains that distinction, we risk getting into a
> terrible muddle.
> 
> > I tend to agree with this position. However, I would take it one
> > step further -- I believe that these "uniquely generated
> > resources" should have consistent, repeatably generated URIs.
> > That is, all parsers should assign the same genid to the same
> > resource.
> 
> do you really mean this last claim?
> I suspect you meant that all parsers should assign a predictable genid
> given a common RDF/XML description mentioning a resource. 'all parsers
> should assign the same genid to the same resource' would be magic, since
> many times parsers won't have that information accessible.

Dan,

just to provide a pointer, a whole while ago I proposed an algorithm for
doing exacty that "magic". A summary of the proposal can be found at
http://nestroy.wi-inf.uni-essen.de/rdf/sum_rdf_api/ under "URI
generation for anonymous resources" (by Peter Hannappel and Reinhold
Klapsing). I believe, if needed, this algorithm can be tweaked to
eliminated the problems wrt using XOR (as pointed out by Brian long
ago).

I still think anonymous resources first need to be resolved as a model
issue. Then, we can move to the syntax. BTW, well-known public names
introduce another danger, which can be even more malicious that
generating ad-hoc URIs: if I'm using danbri@w3.org as an identifier for
Dan's email address, and (mis)using for identifying Dan himself, I can
get into a worse trouble as compared with using two ad-hoc, not as
well-known, but sufficiently unique URIs that allow me to distinguish
that I'm dealing with two separate entities. When I have two different
resources, they still may turn out to represent the same thing. In
contrast, if I'm using a single resource for representing several
different things, I'm in a bigger mess.

Sergey
Received on Friday, 15 June 2001 21:32:03 EDT

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