Re: Experimenting with Namespaces - DTDs?
David Megginson (ak117@f...) writes: > Personally, I'd recommend architectural forms over namespaces if > you're concerned with DTDs, since architectural forms have several > major advantages: David is right. But I would go farther: XML Namespaces are a snare and a delusion. With their use of colon syntax, they lull one into thinking that that are about class inheritance. They are not. Instead, what the namespace thing does is to collapse all the structure of the classes of the inherited-from DTD into a salad of element types which is very correctly termed a namespace rather than an architecture. All that RDF was looking for was a way to guarantee global uniqueness of element type names, and if we ever try to get anything more than that from namespaces, we are on very thin ice indeed. If the inherited-from DTD is already a tag salad, in which all the element types are a big OR group in the content model of the document element, namespaces can work quite well. If, however, an element type has different meanings depending on its context (and most architectures necessarily have this characteristic), then collapsing such an architecture into a namespace can actively interfere with information interchange. I think RDF would benefit substantially, in terms of its understandability, its implementability, and its flexibility, if it were described in terms of inherited architectures. In fact, I think it cries out for an architectural perspective, in which the knowability and significance of element context is preserved. I suspect that RDF's formal rigor would benefit, too, even though its formal rigor is already formidable. (I'm basically impressed by RDF; it's the product of much excellent thinking, I think. I just want MORE!) To be entirely fair and truthful, I must personally accept a share of the blame for this namespace mess; I was present at the first Dublin Core meeting, and, awed by the momentousness of the occasion, I evidently failed to make the case for using architectures for metadata. My later contributions to the W3C XML discussions about namespaces were evidently not persuasive, either. In my own defense, I would argue that this is entirely understandable; it's a subtle issue; nobody has much experience with metadata architectures; what experience there is is dominated by methodologies like MARC that rely on lists of uniquely named fields; and, most of all, the need for even a partial solution to the metadata problem is phenomenally intense. Anyway, all is not lost. This namespace thing is a mistake that will necessarily be corrected, simply in order to support the needs of civilization in an XML-dominated world. The way toward a solution is already paved by an ISO standard (ISO/IEC 10744:1997 Annex A.3) that is being adjusted to accommodate the syntactic limitations of XML (i.e., its lack of #NOTATION attributes). It is implemented in the SP parser and in other software systems, and it is already being used in many industrial contexts. It's the right sort of answer, it's not going away, and its usage is accelerating rapidly; there was a manyfold increase in the number of papers reporting its use at SGML/XML 97. And, anyway, the need for metadata interchange far outstrips RDF's present scope. I hope and believe that many powerful metadata architectures -- including elegant ones that can't be squashed flat and remain useful -- will be multiply inheritable. That way, there can be a marketplace of architectural ideas for metadata in which the full power of context can be exploited. I'd like to see RDF evolve in that direction. -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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