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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: Sun, 17 Jun 2001 15:49:30 -0700
Message-ID: <3B2D33FA.C5CA8B4C@db.stanford.edu>
To: Graham Klyne <Graham.Klyne@Baltimore.com>
CC: RDFCore WG <w3c-rdfcore-wg@w3.org>
Graham,

as I already emphasized earlier, I think anonymous resources shoud be
eliminated from the spec, at least from whatever is the RDF model. I
guess we have to keep them in the serialization syntax for backward
compatibility. In this case, see my suggestion below as just a possible
way of making the spec more precise. Another approach is to leave the
generation of URIs to the parsers, and deprecate the practice. Seems
that we have to wait with this issue until the "core" model is in place.

Sergey


Graham Klyne wrote:
> 
> Sergey,
> 
> I vaguely remember this being raised, and must say I have deep reservations
> about that approach.
> 
> Right now I cannot say exactly why I think this is a problem, and I won't
> fight the case here, other than to note that I might object later if/when I
> can crystalize my concerns.
> 
> (Part of my objection is that any mechanism that is based on merely
> statistical uniqueness (i.e. digest-based) has no place in the core of the
> RDF framework.  In an appendix to RFC 2938, I have calculated some
> probabilities of collision using MD5;  the numbers of digest values in use
> does not need to be astronomically large (c. 10^18 or so) before the
> probability of collision becomes quite significant.  Applications may
> choose to take such statistical chances, but I don't think a fundamental
> technology framework like RDF should do so.)
> 
> #g
> --
> 
> At 06:58 PM 6/15/01 -0700, Sergey Melnik wrote:
> > > 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).
> 
> ------------------------------------------------------------
> Graham Klyne                    Baltimore Technologies
> Strategic Research              Content Security Group
> <Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
>                                  <http://www.baltimore.com>
> ------------------------------------------------------------
Received on Sunday, 17 June 2001 18:23:24 EDT

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