- From: Alan Ruttenberg <alanruttenberg@gmail.com>
- Date: Wed, 11 Nov 2009 10:51:42 -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 Wed, Nov 11, 2009 at 2:48 AM, Jeremy Carroll <jeremy@topquadrant.com> wrote: > >>> Alan Ruttenberg wrote: > >> 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. > > If you bothered to read the reference to RFC 3986, 5.1.1 you would see that > section 5.1 explains how all Web retrievable documents that involve relative > IRIs have a base. 5.1.1 describes one of four ways that a base URI can be established, in this case by embedding a declaration of it explicitly in the content. When I said "Not all *serializations* have an xml base." I meant not all documents use the method described in 5.1.1. I referred to the method in 5.1.3 elsewhere in my message. > Since we were talking about pragmatic issues to do with managing ontologies > and namespaces, There are ontologies to manage. I contest that there are namespaces to manage. > Now that is a disconnect. XQuery concerns the actual syntactic structure of > an XML document. This has very little to do with the semantics, and except > with a lot of care and attention, the systematic use of XQuery with semantic > web documents will get you into trouble. The point was to demonstrate that there are, at the level of XML itself, mechanisms to determine equality of documents that goes beyond the surface syntactic structure. OWL's (via RDF/XML) use of XML similarly is at a level that does not depend on some details of the surface syntactic structure. > (I take it that the implementations you use do not make any local copies at > all of any of the documents you use ... hmmm ... they must be very fast. I am involved with development of OWL ontologies on a daily basis and have to deal with performance issues of a variety of sorts. A search of google will find a reasonable amount of detail on such efforts. I do use local copies. It is a royal pain. Having different tools inject idiosyncratic behaviors, such as ignoring owl ontology names makes it even more difficult, such experience being the impetus behind my first email in this round. I proposed, within the working group, that we make this easier, but it was not considered to be something appropriate for the working group to undertake in full. There is at least *some* mechanism available now, via the versionIRI, to make this possible in a supported way. http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Versioning_of_OWL_2_Ontologies In addition there is rich support for caching associated with the http specifications, should your ontologies be the sort that are on the web. > Here's another part of the OWL2 spec that you seem to have failed to read: > http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Imports > [[ > For example, in order to access the above mentioned ontology document from a > local cache, > ]] > which is other words for allowing a copy to be stored locally. Alan, please > read the specs before making further groundless bold assertions.) I'm sorry, I don't believe I made any assertions which would contradict this. Could you please cite what I said that makes you think so? >>> , and for relative URI computations to be made correctly seems to be the >>> primary intended purpose. Really? That section says nothing about relative URI computations. > I didn't find the text in the OWL2 specs that actually talks about > dereferencing the imported IRIs ... do you have a pointer please. http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Ontology_Documents Ontology documents are not represented in the structural specification of OWL 2, and the specification of OWL 2 makes only the following two assumptions about their nature: * Each ontology document can be accessed via an IRI by means of an appropriate protocol. * Each ontology document can be converted in some well-defined way into an ontology (i.e., into an instance of the Ontology UML class from the structural specification). http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#IRIs discusses other details, including: * Each IRI must be absolute (i.e., not relative). [speaking of IRIs in the structure specification] * If a concrete syntax uses this IRI abbreviation mechanism, it should provide a suitable mechanism for declaring prefix names. Furthermore, abbreviated IRIs are not represented in the structural specification of OWL 2, and OWL 2 implementations must exhibit the same observable behavior as if all abbreviated IRIs were expanded into full IRIs during parsing. Concrete syntaxes such as the RDF/XML Syntax [RDF Syntax] allow IRIs to be abbreviated in relation to the IRI of the document they are contained in. If used, such mechanisms are independent from the above described abbreviation mechanism. The abbreviated IRIs have the syntactic form of qualified names from the XML Namespaces specification [XML Namespaces]; therefore, it is common to refer to PI as a namespace and rc as a local name. This abbreviation mechanism, however, is independent from XML namespaces and can be understood as a simple macro mechanism that expands prefix names with the associated IRIs. -Alan > >> Regards, >> Alan >> > > Jeremy > >
Received on Wednesday, 11 November 2009 15:52:43 UTC