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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Model issues was: A certain difficulty
-----Original Message----- From: David Megginson <david@m...> To: xml-dev@x... <xml-dev@x...>; www-rdf-interest@w... <www-rdf-interest@w...> Date: Friday, February 25, 2000 6:07 AM Subject: Re: A certain difficulty >Pierre-Antoine CHAMPIN writes: > > > I would not say that either ! > > I find the RDF model very simple and uniform (it's all about triples) > > which makes its elegance... and for some people its weakness ! > >Unfortunately, it's not about triples. The only way to discover the >true RDF data model is to reverse-engineer it from the XML, and it >turns out that there are at least six components (not three) in each >statement: > > subject > subjectType (global id, local id, URI pattern) The global ID and local ID are IDs, so the semantics should be the same. A reference with a #fragmentID is taken as a reference to a part of (or view of) a document, while a reference without a # is taken as a reference to the document.There is an unspoken problem that in the RDF spec a reference to a subtree of an XML document containing RDF is taken to be a erference to the RDF object. .........(1) The URI-pattern I agree is a big problem, and I think a lot of people would have wished it not there. I wonder how many systems implement it. It seems to me best to put it off to a level of logic above the basic RDF. .............. (2) > predicate > object > objectType (literal text, literal XML markup, reference) The object being the union of litteral types and reference to node is reasonable: the object may be represented as a pair (type, value) for example (or some other syntax or a pointer into a different part of memory or a pointer to a self-typed object or whatever.) You could argue (and people have i understand) that the same ought to hold for the subject of course. ............... (3) > objectLang This is a mess pure and simpe: it is in the syntax and not in the model. How did that happen? The syntax should not have bowed to the internatoinalization community with a syntactic nod, but instead asked for an RDF vocabulary for language. It should be removed from the synatax. ..............(4) My nurdlings on two ways of doing it are in http://www.w3.org/DesignIssues/InterpretationProperties >These are not simply syntactic artifacts -- it's information that >*must* be exposed through any RDF API, and thus, part of the core >model, independent of the peculiarities of the XML markup (note that >I'm assuming that bagID, etc. are predigested). The URI patterns >(aboutEachPrefix), especially, make it much trickier to do any >relational database implementation of RDF, since you the set of >possible subjects is open. yes, abouteachprefix was a mistake in retrospect. Here are 4 issues for an RDF M&S retrospecive post-Rec issues list! Ralph or Dan Brickley was going to draw one up I think. > > In the contrary, the XML syntax is a bit confuse, true. > >Yes, it is also unnecessarily confusing. > > > In my point of view, the problem comes from the recommandation > > mixing modeling and syntaxic aspects (I won't mention semantic > > aspects !) in a way it's hard to differentiate them without some > > RDF experience. > >The problem is that the model as presented is naively simple, and the >WG failed to notice that the XML syntax is not based directly on that >simple model. > > >All the best, > > >David > >-- >David Megginson david@m... > http://www.megginson.com/ > *************************************************************************** This is xml-dev, the mailing list for XML developers. To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev List archives are available at http://xml.org/archives/xml-dev/threads.html ***************************************************************************
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