[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] X-Schema concerns
The latest arguments regarding the usefulness of XML schema languages versus DTDs are the most interesting. I have long used what are sometimes called 'reflective' object models, where the 'meta-data' can be thought of as a specialization of 'data'. This unified approach in my experience is more than a conceptual nicety, it provides long term implementation advantages. A single model for creation, storage, queries, fetches, modification, browsing, editing, translating, etc means that your large scale mature system is simpler to understand and has much less implementation code in it. For instance, the reflective system I have most recently constructed, has a browsing tool, where with only one tree view model, can browse through meta-data and data 'boundaries'. This unified approach, I find, pays off immediately in very practical terms. So while programming languages have long had a 'programming' language to handle meta-data constructs and a 'run-time' environment to handle data constructs, this separation is in fact an implementation choice, to support higher performance static executables. XML is not currently, and may never be, a high performance static approach, so why not enjoy the benefits? I heartily vote for moving quickly on getting meta-data into normal XML format and moving away from DTD's. On the other hand, I have major concerns regarding the current the XML-SCHEMA efforts. It reminds me a little of SQL3, where the spec has the 'kitchen sink' feel to it. This is for understandable and hard to resist reasons, but none the less a little scary. XML is or soon will be, the synthesis of the document and data modeling worlds. However the current efforts seem to me at least to be highly skewed towards document expertise, and the data modeling expertise is not as evident. I believe that the data modeling world, having to live in the rough and tumble of high performance large scale reliable delivered systems (object and relational environments/servers), has schema that are much less ambitious than the document world. I personally would start with a much simpler XML schema, implement carefully, live with the constraints, and slowly learn what is *required*, as opposed to what is conceptually interesting or complete. I have never seen a system that is that complex start serving a useful purpose quickly. cheers, erik 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 (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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