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Re: Q to implementers: Resource identifiers - XML Names and/or (concatenated) URIs? (was RE: rdfs.isDefinedBy...)

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Mon, 10 Jun 2002 12:52:17 +0300
To: "ext Thomas B. Passin" <tpassin@comcast.net>, RDF Interest <www-rdf-interest@w3.org>
Message-ID: <B92A5181.166C1%patrick.stickler@nokia.com>

On 2002-06-09 23:09, "ext Thomas B. Passin" <tpassin@comcast.net> wrote:

> [Uche Ogbuji]
>>> - the suggested URI -> XML Names splitting method is so flawed as to not
> be
>>> responsibly implementable (i.e. you can't generate valid LocalParts by
>>> splitting on non-Name characters, but can if splitting on non-NCName
>>> characters. However, using the latter method produces differently
> invalid
>>> results, e.g. if splitting
>>> urn:NewsML:afp.com:20000811:010607144425.x6pxrl6k:1)
>> Yes.  We have run into this problem quite a bit at Fourthought because we
> use
>> UUID URNs in many projects.  The only solution we have found is a horrible
>> hack: to give resources UUIDs, and also aliases in forms that are
> compatible
>> with RDF/XML, and then introduce equivalence statements between the ID and
>> alias.
>> I think the WG desperately needs to fix this.
> Yes - what Uche said.
> There must be only one way to go from URI references to prefixes and back
> again. That way should be compatible with XML Namespaces.  It should always
> be possible to use prefixes as aliases for a "base" URI to make it easier to
> read and write RDF/XML by hand (I say "base" in quotes to distinguish it
> from "xml:base", since the two may not turn out to be the same).  After all,
> it's done all the time in N3, why not everywhere?
> Cheers,
> Tom P

The fact is that qnames and URIs are two competing schemes for global
naming, and URIs do not support the structure and contextual semantics
defined for qnames -- therefore a fully bidirectional mapping without
loss of information is just not possible. URIs will always represent less
information than a qname.

The solution IMO is for the RDF/XML serialization should be redone in such
a manner that *no* qnames are used to denote resources which are denoted
by URIs in the graph. I.e., do away with any need to perform a qname<>URI
mapping. Resources are ever and only identified with URIs, whether in
RDF/XML or the graph.



Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Monday, 10 June 2002 05:48:10 UTC

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