[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XML Schemas: Best Practices
Roger L. Costello wrote, replying to Mike Ripley: > > Given this, the advantages of redefining can now be thought of in > terms of refining the semantics of some Chameleon component to meet > the specific semantics of the schema being created. So for example, > I might refine <car> to have enumerated types for the specific cars > I'm dealing with (e.g., say I work for Audi and I only need to have > Audi cars in my schema). The semantics have been refined from 'all > cars' to 'Audi cars', but it's still the same type of entity being > modeled. If, on the other hand, I work for Amtrak, I shouldn't use > the Chameleon component <car> to hold railroad cars, since > semantically these are different types of entities. > > I think this approach also limits the > "component-change-impact-rippling-problem" raised by Mary > Pulvermacher. Changes to Chameleon components will be limited to > changes that still maintain the component's semantics, so something > won't break downstream due to a semantic change in a Chameleon > component. > Analogous to type restrictions as used in xml-schema - the recommended practice would exclude the analog of type extensions. I agree. I'm not so sure about talking about "refining the semantics", though. Any semantics are hidden in the model (which may not formally exist) behind the component, and can only be gotten at by reverse engineering the component or by reading documentation about the component. A person (a re-user, not the original creator) would have to refine the component based on a hypothesis about the original semantics, not based on the component itself per se. Good naming helps with this, of course. Cheers, Tom Passin
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