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Re: Namespaces in guide ontologies

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 19 Jun 2003 15:31:08 +0100
Message-ID: <3EF1C92C.7070707@hplb.hpl.hp.com>
To: Sean Bechhofer <seanb@cs.man.ac.uk>
CC: www-webont-wg@w3.org



This looks correct ....


I suggest that:
- all versions of the doc use an xml:base
- all versions of the doc use xmlns with  URI refs which work with that base.
- that the xml:base should be the undated publication URL i.e.

    "http://www.w3.org/TR/owl-guide/food.owl"

Jeremy


Sean Bechhofer wrote:

> 
> I believe there are still some anomolies in the guide ontologies at:
> 
> http://www.w3.org/2001/sw/WebOnt/guide-src/food.owl
> http://www.w3.org/2001/sw/WebOnt/guide-src/wine.owl
> 
> In, for example, food.owl, there is an xml namespace declaration in the
> RDF header:
> 
> xmlns="http://www.w3.org/2001/sw/WebOnt/guide-src/food#"
> 
> This means that any "vanilla" elements used in this scope will be in this
> namespace, e.g.
> 
> <DarkMeatFowl rdf:ID="Duck"/>             [1]
> 
> However according to my understanding of the rules for resolving names,
> which seems to be borne out with experimental evidence from examining the
> result of parsers, the xmlns declaration does *not* apply to attributes --
> by default they get resolved to the base URI of the document. Somebody
> *please* shout if I'm wrong here because to be honest I find this
> namespace resolution highly confusing.... Assuming that I'm right though,
> this means that the statement above is actually saying:
> 
> http://www.w3.org/2001/sw/WebOnt/guide-src/food.owl#Duck
> 
> rdf:type
> 
> http://www.w3.org/2001/sw/WebOnt/guide-src/food#DarkMeatFowl
> 
> which is not, I think, what is intended. In order to make sure that the
> attributes end up in the same namespace, you need (I think) an xml:base
> attribute, e.g:
> 
> xml:base="http://www.w3.org/2001/sw/WebOnt/guide-src/food"
> 
> As they currently stand, I believe the example ontologies are *not* DL due
> to this mismatch, as a number of things are not explicity typed. For
> example, there is a statement:
> 
> <owl:Class rdf:ID="DarkMeatFowl"/>
> 
> This then refers to a uri
> 
> http://www.w3.org/2001/sw/WebOnt/guide-src/food.owl#DarkMeatFowl
> 
> which is not the same "DarkMeatFowl" used in the earlier rdf:type
> assertion, and this means that [1] is using an "untyped" class.
> 
> I think the /TR/owl-guide ontologies have the same problem.
> 
> It might be worth a note in one of the documents about this kind of thing
> -- as I said above, it gives me a headache and I'm sure I'm not the only
> one.....
> 
> Cheers,
> 
> 	Sean
> 
> 
Received on Thursday, 19 June 2003 10:33:28 GMT

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