[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Request for a poll: (was RE: Datatypes vs anarchy)
Urrp. That is PRECISELY what bedevils X3D and it was brought up several times by different sources during the XML Schema work. We did a long thread on the power and ways of groves as a result. Henry says, "almost but not quite groves". VRML has the problem of orignally defining the abstract node/fields in the same syntax as the actual instance language. That made it difficult when the time came to add an XML syntax. The problem can't be succinctly stated: o One abstract object model; multiple syntaxes. It has become madness and split the VRML efforts cleanly into multiple efforts (X3D, RM3D) and diverging models. Why? XML isn't just syntax. It has an explicit element/attribute separation of namespace. Elements can have have attributes. Attributes can't have elements as children. VRML97 has nodes/fields. Children fields can have nodes. Groves could handle that fine. XML can't. The bedevilment was to make a clean map, we needed the wrapper elements to emulate some of the fields (eg, children). To an XMLer, it looks silly because XML doesn't need those. So what you are suggesting looks right, but I contend we are just going right back down the same path the groves guys went down. Nodes is nodes, properties is properties, someone chooses names. Len Bullard Intergraph Public Safety clbullar@i... http://www.mp3.com/LenBullard Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: Rick Jelliffe [mailto:ricko@a...] Yes. And there is a nice design issue here for the future too: Perhaps what we need for a schema language is something along the lines of <schema> <conceptual-model> ... </conceptual-model> <language-binding> ... </language-binding> </schema> In XML Schemas, we have found all sorts of nice abstractions (components) for what goes on in a language. Yet the conceptual modeling people (I think Robin Cover and Peter Chen might concur) think that the bottom-up approach is odorous. That is why, to jump on my hobbey-horse, I don't see that we need more grammar-based schema languages (not to say that we shouldn't continue to perfect and mate existing ones). Instead, we need to start thinking about what schema languages would be needed to implement the above kind of schema. Personally, I think that a schema language made from ER for the conceptual model and a Schematron-like language to do the language binding might be a nice fit (if Schematron-like languages can be extended to act generatively.)
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