- From: Alan Ruttenberg <alanruttenberg@gmail.com>
- Date: Tue, 10 Nov 2009 21:59:40 -0500
- To: Jeremy Carroll <jeremy@topquadrant.com>
- Cc: Holger Knublauch <holger@knublauch.com>, Ian Emmons <iemmons@bbn.com>, Simon Reinhardt <simon.reinhardt@koeln.de>, semantic-web@w3.org
On Tue, Nov 10, 2009 at 5:30 PM, Jeremy Carroll <jeremy@topquadrant.com> wrote: > Hi Alan > > you seem to have forgotten yourself, or at least that bit of yourself that > read the OWL 2 documents. Don't think so. > > Alan Ruttenberg wrote: >> >> As far as any of the semantic web technologies go xml:base *does not >> exist*. The specs know *nothing* about it. Nor should they. >> >> > > I read: > http://www.w3.org/TR/2009/REC-owl2-xml-serialization-20091027/#IRIs > /[[ > MUST/ be resolved against the respective /base IRI/ as specified in the XML > Base specification [XML Base > <http://www.w3.org/TR/2009/REC-owl2-xml-serialization-20091027/#ref-xml-base>]. > ]] This is an aspect of syntax of some serializations of OWL. Not all serializations have an xml base. Therefore I classify xml:base as something to do with XML in particular and OWL and RDF only insofar as OWL can be serialized using XML. As you point out in your previous email, base and prefixes provide a way to abbreviate URIs. There is no other specified purpose for them. In my opinion, any other use for them is a bad idea at least because xml:base does not exist in all serializations and we want stuff to work independent of choice of serialization, if at all possible. So I maintain: the "semantic" part of semantic web technologies, knows nothing of xml:base. > I read > http://www.w3.org/TR/2009/REC-owl2-primer-20091027/#Ontology_Management > and see the second set of examples using xml:base in both the RDF/XML and > the OWL/XML And not in the manchester, nor in the turtle. > The automated converter for the OWL2 tests appears to add xml:base for both > RDF/XML and OWL/XML formats, > e.g. see > http://owl.semanticweb.org/page/Qualified-cardinality-restricted-int i.e. it serializes the ontologies properly, by which I mean it correctly uses the facilities of XML. > The OWL1 test cases all have explicit xml:base So? xml:base is not required to be explicit in any XML document. If not explicit it gets defaulted to the location of the document. > What is the role of an xml:base, well that is explained in RFC 3986, section > 5.1.1. This explicitly takes precedence over the retrieval URI, when doing > base conversions. > > In particular, the function of TopBraid Composer which adds an appropriate > xml:base declaration to a file to allow a copy to be stored locally zing. The disconnect, as I see it, is the connection between "adds an appropriate xml:base declaration" and "allow a copy to be stored locally". There is no such thing in the specification as "allow a copy to be stored locally". There *is* such a thing as an XQuery giving the same answer when posed against different XML files. >, and for relative URI computations to be made correctly seems to be the primary > intended purpose. Sure. But making decisions other decisions based on the value of the xml:base isn't part of the spec, and this is what is being done. Decisions on what files to import (at least in OWL) are based on the ontology URI, not the xml:base, except to the extent that in XML serialized files, the xml:base *might* have been used to parse the value of the ontology URI. > (Of course, there is also a normative dependency from OWL2 to xml:base via > RDF/XML Syntax) A dependency of certain OWL2 *serializations* on xml:base via both the RDF/XML syntax and the XML serialization. But OWL the language is independent of any particular syntax, and so the attempt was to define the behavior of imports in a way that did not depend on a particular syntax. There is a single exception to this goal, there for backwards compatibility with OWL 1, which has to do with the way that imports of RDF documents are handled. http://www.w3.org/TR/2009/REC-owl2-mapping-to-rdf-20091027/#Resolving_Included_RDF_Graphs Regards, Alan
Received on Wednesday, 11 November 2009 03:00:35 UTC