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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Semantic Web permathread, iteration n+1 (was Re: [x ml-dev
 On Jun 3, 2004, at 9:32 AM, DuCharme, Bob (LNG-CHO) wrote: > the semantic web is something that > will inspire great ideas that get implemented in a different, more > practical > project? > For what it's worth, that's exactly the point I was trying to make in my response to Len. Elliotte suggests that the essential subset to do real semantic integration will be XML+namespaces, and wonders what RDF brings to the table. I'm a fairly hard-core RDF-skeptic myself, so I'm sympathetic. Nevertheless, to me it is OWL that provides the mojo powering my late-blooming interest in the semantic web stuff. Of course, OWL *is* RDF, but it has a syntax that is more accessible and usable as XML. For example, look at the ontologies under http://www.w3.org/2004/02/wsa/ (the OWL formalization of the W3C Web Services Architecture Note). Maybe I'm not the best judge, but these seem fairly understandable to me, at least compared to other formal notations for this kind of thing. It *was* useful to use OWL as the formalism because we (or actually the Carnegie-Mellon people who did the work!) could use the various OWL tools to check for undefined terms, multiple definitions of the same term, and generally to identify gaps and inconsistencies in the architecture. In the day job, we have seen some real synergies between pure XML technologies such as XQuery and semantic technologies based on OWL. I don't have the details, but I believe we can demonstrate how a huge ontology such as OpenCYC can be used more efficiently and effectively by a reasoner by storing the ontology in an XML database and selectively pulling out relevant subsets in chunks. That works best if there is coherence between the XML syntactic structure of an ontology and the logical structure of the network of triples. As I understand it, that is hard to pull off in raw RDF, but more effective in OWL. Another point I'd make vis a vis what OWL adds over raw XML is its vastly richer notion of a relationship. Of course, XML gets a lot of mileage with basically two built-in relationships, "has-property" (that is, attributes on elements) and "contains" (subordinate elements). The basic HTML hyperlink that Google exploits so well is of course another that is easily represented in XML. I won't deny that one can get an awful lot of benefit from these, especially when it is a human consuming the information, but I'll suggest that OWL's much richer relationships (and the hierarchy of support for them in OWL-Lite, OWL-DL, etc.) prove their worth when dumb software is consuming the information. Again, I am only at the periphery of this stuff so I can't explain or defend it in detail, but am just offering my impression that OWL allows one to leverage the undeniable strengths of XML in a way that RDF (or at least RDF-XML) does not. I would be happy to be set straight by people who have a better grasp of all this! 
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