RE: Co-operating with Architectural Forms
Joe English answered this much better than I can. The insights are appreciated from both parties. len -----Original Message----- From: Bill Lindsey [mailto:bill@b...] Bullard, Claude L (Len) wrote: > > But both are just means of association with respect > to semantics. And we don't have a standard means > of describing semantics. Seems to me that semantics are most naturally related to types. ... But we're not allowed to use that word here, huh? > No matter how we slice this, James is right. If we > want to associate semantics/behaviors, something > more layered has to be at the other end of that > association. What do we call the set of instances that can be mapped to a specific base architecture through a single architectural form? What do we call the set of all instances amenable to processing by a single DSDL? If we had names for these things, we might find we had a nice hook to which processors could attach semantics. I'm becoming convinced that all XML documents have an important property and that we don't have a good name for that property. "Document type" comes close, but I think the term carries too much baggage to carry a sufficiently precise or a sufficiently general meaning. Root element namespace+localname is too imprecise. I'll try to describe this property below using the decidedly un-catchy term "representational form" an alternate term might be "lexical type". Documents are created with the intent of communicating some information. The document creator encodes the information according to the rules or conventions of some representational form(s) in order that some processor(s) can get at that information. Representational forms define sets. A document instance either is or is not a member of the set defined by a particular representational form. An instance is often a member of many sets -- it has multiple values for for its "representational-form" property. There is usually (always?) one predominant representational form that most precisely matches the instance creator's intent. These sets may nest (subset through restriction constraints) and intersect. All XML documents are members of the "well formed XML" representational form. These representational forms may be used as contracts. Document instances can be tested to see if they conform to the rules. These rules may be expressed in any number of schema languages, procedural code and prose documentation. We often define specific processing (i.e. XSLT stylesheets, DSDL validating) for specific representational forms. Which processing we choose depends largely on our local context. It is useful to be able to give distinct representational forms distinct names. It is often useful for a document to assert, in the instance, that is a member of the set defined by a representational form. We might deduce the form's name through an instance's DOCTYPE declaration or the root element's namespace + local name. There are problems with both of these approaches. What I don't know: * Is the representational form property intrinsic, extrinsic or emergent? * Is this property fixed for the life of the document, or does it change over time? * Could this property be also be obtained for elements?
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