Re: Are we losing out because of grammars?
At 09:45 AM 1/29/01 +0100, Eric van der Vlist wrote: >You're right that there is probably nothing very new here, but I am >afraid I don't get your point. > >Do you mean that such large systems cannot be modeled, that a single >model cannot be shared by all the involved parties or that schema >languages should try to (better) take this requirement into account ? Single models (monolithic) fail in the real world not in the theoretical world. In theory, people in a smoke filled room can agree a top-down model of data interchange. In practice, the cannot. In theory, developers can manage the state-space explosion inherent in processing monolithic content models but in practice they cannot. I think the mantra that "content + presentation == document" is part of the problem. In reality there are two main sub-divisions of "content": "semantics + aggregation + presentation == document" Agreeing semantic elements (invoice, voltage, footnote) is far more politically/technically feasible than agreeing aggregation elements (ledger, TV set, Technical Manual). Moreover, I think a multi-dimensional XML modelling technique in which the *expression* of the aggregation is itself an XML instance, it a powerful and general modelling approach worthy of consideration in many contexts. There are a number of analogies. All are useful to some degree but break down if you push them too far... Polymorphism - a containership model in which the type of the things contained is not relevant. Merchant Shipping - what has standardized? The design of the ship or the design of the containers loaded on to the ships and subsequently transported by truck/rail? Bottom Up Analysis - start by modelling the component units of a system and work upwards towards ways of agregating them together. Tupperware (tm) - A containership model in which content and containers can be intermixed. The contents of the containers is never modelled in the outer container(s). regards,
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