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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Proposal for src files
 At 09:22 AM 4/1/98, Peter Murray-Rust wrote: ><PROPOSAL> >Is it possible to combine these two so that we express a DTD in a standard >XML notation? Many of us do this already, but I suspect that our tagset and >syntax vary. If we could agree on this - and I don't see this as >technically difficult - we could help both communities. It is not technically difficult--it is, however, practically impossible except in the most trivial way (a direct transliteration of DTD syntax) unless it is *explicitly* defined as a base architecture with very clear rules for specialization. And even then, developing that architecture will be difficult at best. The reason it's practically impossible is because getting agreement among a community of interest as wide and varried as the XML community on a subject of such importance as how to represent the definitions of document types is one of the hardest types of things there is to do. There are simply too many different ways to do it, too many different ways to represent things, too many interested parties. The degree of expressibility of schemas is open ended, meaning that any design, to be useful, must be maximally extensible. Defining extensible languages is hard. I personally think that trying to define a common markup approach to DTD representation is a waste of time: the answer is either obvious (Wayne Wohler did it over 5 years ago) or impossible to achieve consensus on. The first is not useful compared to the cost of defining and maintaining it, the second cannot be achieved by any sort of consensus-based approach. So there's no point in bothering. The minimum abstractions needed to define element types are already defined by the SGML property set--if your schema language can get you to these abstractions, fine. I say let groups define their own schema approaches without bothering to find too wide of a consensus. If one particular approach gains widespread acceptance, then fine. If it doesn't, we're no worse off than we were before, *but* we haven't wasted a huge amount of a scarse resource on a doomed effort. This provides opportunities for vendors to distinguish themselves by providing different types of validation and constraint support. As long as they always support normal DTD syntax, I see that as a good thing--if someone like Microsoft produces a product that helps me create better data repositories, then I'm happy to buy and use it, as long it accepts and generates normal DTDs with the level of fidelity I require. But why should I give Microsoft (or anyone else) free engineering support by being involved in a schema development effort? It doesn't make sense to me. If they want my help, they can pay me. I already have what I want and need and I'm capable of providing for myself if I need more (as is anyone with a copy of Lark and a Java book). As long as we have DTD syntax I can ignore or use any schema efforts as I please, because my ability to use normal DTDs is assured. The cost of writing schema-to-DTD-syntax transforms will always be lower than the cost of participating in wide-scope schema definition efforts. But maybe I'm just a crank. Cheers, Eliot -- <Address HyTime=bibloc> W. Eliot Kimber, Senior Consulting SGML Engineer Highland Consulting, a division of ISOGEN International Corp. 2200 N. Lamar St., Suite 230, Dallas, TX 95202. 214.953.0004 www.isogen.com </Address> 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/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe 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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