[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: A Plea for Schemas
From: Tim Bray <tbray@t...> >Where I work, people aren't satisfied until there's running code that >does useful stuff, and the schema-ware is an essential but fairly small >component of getting there. One of my hopes for new schema languages (especially those using XML element syntax) is that, like any data with generic markup, there may be useful and unexpected applications made possible. The Xeena people were nicely surpised that a DTD could be used to generate a structure-editor: a better schema language will allow better such editors. Already there is a spread of reasonable opinions on schemas: * they need to integrate into existing systems as much as possible (the XML Schema approach?); or * they only need to provide information that generating and receiving software do not already have (the SGML DTD approach?); * they need to be as complete as possible (the EXPRESS approach?); or * they need to be simple and elegant (the XML DTD approach?); A schema that provides enough information becomes useful as a declarative programming tool. (For example, I have a working Schematron that generates RDF based on tree-patterns: it is an automated external markup tool, yet it is driven by a schema.) Tim is of course correct that a schema is only part of the whole picture, but a schema language can be judged on how readily it allows useful systems and tools to be built. That being so, it may be a strong schema system is one which has some 'use' information as well as the "pure" schemas: documentation, forms building, validation, style, etc.: where the type information from the schema can directly be used for some purpose. DTDs provide simple stucture models but also have infoset contributions with #FIXED attributes and default attribute values (i.e., a simple transformation of the instance). This makes them 'impure' as a schema language, but undoubtedly more useful. Rick Jelliffe xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To unsubscribe, mailto:majordomo@i... the following message; unsubscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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