[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Inheritance using DTDs
[Avneet Sawhney <sawhneya@m...>:] > So, since DTD's were not designed to support inheritance, what are > my options here? Even declaring all attributes and elements as > entities is not sufficient. > Will namespaces (and DTD's) be sufficient, or are there any proposed > schemas that have proper inheritance as a required spec? > Sorry if this is obvious, but I would like to know my alternates to > vanilla DTD's. Actually, unless I misunderstand what you're talking about, there is already an ISO standard way of achieving semantic/syntactic inheritance (or, more properly, subtyping); it is already supported by the SP parser for SGML, and it is more extensively supported by GroveMinder for both SGML and XML. The paradigm is variously called "SGML architectures", "architectural forms", "inheritable architectures", "meta-DTDs", "element subtyping", etc. In W3C-land, a similar (and still fairly compatible) paradigm is emerging, variously known as "namespaces" or "vocabularies". If you want to use the full power and rigor of the ISO paradigm in XML, that's just fine; indeed, there is an ISO syntax for using the ISO paradigm with XML (see http://www.ornl.gov/sgml/wg8/document/1957.htm). ISOGEN International Corp is, at least from my perspective, the most visible pioneer in commercializing these ideas. It regularly uses the ISO architectural inheritance paradigm to meet the needs of its consulting and systems integration clients, and they seem pretty happy (and often even ecstatic) about the results. I'll be giving a presentation on this topic at XTech 99 in San Jose on March 7-11 (http://www.gca.org): "Vocabularies: Opportunities for Efficiency and Reliability". Now, if we're talking about what *might* be done in the nebulous future, there do appear to be opportunities for improving the syntax and functionality of DTD notation, so as to support architectural inheritance more elegantly and conveniently (for instance), probably at the cost of increasing the complexity of the notation. However, the ISO standard DTD formalism, as well as XML's currently-almost-identical-to-a-subset-of-ISO DTD formalism, can be used today to declare element types as subtypes of other element types in other DTDs. This has been true since 1997, when ISO/IEC 10744:1997 (http://www.ornl.gov/sgml/wg8/document/1920.htm) was published, but, as was the case with object orientation in general, it takes time for these ideas to percolate throughout the community. -Steve -- Steven R. Newcomb, President, TechnoTeacher, Inc. srn@t... http://www.techno.com ftp.techno.com voice: +1 972 231 4098 (at ISOGEN: +1 214 953 0004 x137) fax +1 972 994 0087 (at ISOGEN: +1 214 953 3152) 3615 Tanner Lane Richardson, Texas 75082-2618 USA 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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