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On Wed, 02 Apr 2014 06:35:48 +1100, Stephen Cameron <steve.cameron.62@g...> wrote: | On Tue, Apr 1, 2014 at 10:15 PM, Arjun Ray <arjun.ray@v...> wrote: | > On Tue, 01 Apr 2014 12:35:36 +1100, Stephen Cameron | > <steve.cameron.62@g...> wrote: | > | a data-model in XML Format (schema) | > | > [...] XML schema formalisms (DTD, RNG, WXS) are for analytic document | > structures, not - as far as I know or understand them - for arbitrarily | > general "data models". | | [...] These formalisms have types and convey structure and relationships | between types. DTD don't have data types at all, besides strings and tokens. RNG defers data typing to external libraries. WXS is fatally infected with DB-think and thus has some bizarre mishmash. Anyone remember gHorribleKludge? (Hi Amy!:-)) There was room to re-invent SGML notations, but no one (except RNG, in a sense) went that route. The ability to represent types _within_ the formalism is quite limited. However, the real nub of the matter is that not all data models are naturally or conveniently reducible to trees, whereas a XML document is in the first instance a tree, and schemas for XML are therefore for trees. The impedance mismatch may be great or small according to context, but to discount it as inconsequential doesn't strike me as wise. | Is there a more suitable formalism for data-models that you make use of? UML comes to mind. | An object-oriented formalism, in UML, uses XML for interchange. With limited traction and success, if Wikipedia is to be believed (and in this instance, I don't see why not). | my concept of leveraging data-models in cost-effective ways, as I tried | to give some examples of, is my key point. Fair enough. In my work, I've never found schemas for XML instances a good starting point, or even a vital consideration, in system design.
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