[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: RDF or UML (Was RE: XML and Healthcare,RDF spec bug was: Re:Default
Thanks guys. Ok, another MMTT that resolves in a choice of the top level systemic definitions. UML gets an edge for having a widely accepted graphic symbol set and is well-supported by existing tools. RDF is favored by some web heros wanting to define their own way to do the kinds of things the PDES folks defined. Tough sell in both cases. Politics is local. Appeals to mathematics are just a choice of systemic definitions. This comment: "With respect to this, I tend to take the pragmatic side: you cannot solve the interoperability problem by generating a wealth of incompatible DTDs (syntaxes)." strikes me as funny. XML does not solve any problems of interoperability, just data portability. Incompatible DTDs are a symptom of a lack of requirements for defining the characteristics of interoperation as predictable behavior over portable data (say, shared). It has been said again and again so this time, shouted: DATA IS PORTABLE. SYSTEMS INTEROPERATE. That is why XML structures are data objects, not classes. Failing to "get it" on that one is behind a lot of the monkey motions of the web. The moon in the water is not the Moon. XML is water. Len Bullard Intergraph Public Safety clbullar@i... http://fly.hiwaay.net/~cbullard/lensongs.ram Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: johns@s... [mailto:johns@s...] Sent: Friday, July 21, 2000 8:10 AM To: Bullard, Claude L (Len); 'Jonathan Borden' Cc: xml-dev@l... Subject: RE: RDF or UML (Was RE: XML and Healthcare,RDF spec bug was: Re: Default Namespaces - why don't they apply toattributes?) Len asked: "How does RDF stack up next to UML for modeling semantics?" It seems to me that RDF is at least 2 meta levels higher than UML (the modeling language). Here is what UML 1.3 says about meta levels (excuse the formatting): "Layer Description Example meta-metamodel The infrastructure for a MetaClass, MetaAttribute, metamodeling architecture. MetaOperation Defines the language for specifying metamodels. metamodel An instance of a meta-metamodel. Class, Attribute, Operation, Defines the Component language for specifying a model. model An instance of a metamodel. StockShare, askPrice, Defines a language to sellLimitOrder, describe an information StockQuoteServer domain. user objects (user data) An instance of a model. <Acme_SW_Share_98789>, Defines a specific 654.56, sell_limit_order, information domain. <Stock_Quote_Svr_32123>" So, I think that RDF is at the meta-metamodel layer. UML is at the model layer (with a subset based on UML Class diagrams at the metamodel layer). In other words, RDF is a language that is so generic you can model any meta-model in it. By the time you get to the model layer, languages are specific to the thing being modeled. So UML is specific to object models (it knows about visibility for example, a concept that doesn't exist in data models). IDEF1X, on the other hand, is specific to data models (it knows about identifying relationships, a concept that doesn't exist in object models). Other modeling languages exist for modeling integrated circuits (VHDL) and so on. Yours, John F Schlesinger SysCore Solutions 212 619 5200 x 219 917 886 5895 Mobile -----Original Message----- From: Bullard, Claude L (Len) [mailto:clbullar@i...] Sent: Friday, July 21, 2000 9:25 AM To: Jonathan Borden Cc: xml-dev@l... Subject: RDF or UML (Was RE: XML and Healthcare,RDF spec bug was: Re: Def ault Namespaces - why don't they apply toattributes?) How does RDF stack up next to UML for modeling semantics? Len Bullard Intergraph Public Safety clbullar@i... http://fly.hiwaay.net/~cbullard/lensongs.ram Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: Jonathan Borden [mailto:jborden@m...] 1) RDF was designed for modelling the rich types of semantic relationships
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