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Re: [xml-dev] Interoperability
Date: 11/14/2001 7:34:00 PM
Tim Bray wrote: > As to Joe's problems above, I tend to think that one of > the best uses of a DTD is for documentation. I find them > laughably inadequate for some parts of business validation > and real overkill for others - I just don't find much > use for them at interchange time. Same here, except that for most of my applications DTDs are neither overkill nor inadequate; they're usually just right. But for document processing and interchange, the value added (mostly whitespace significance, default attribute values, and indicating ID-ness) isn't worth the administrative overhead. Earlier Sean quoted me as saying that I had given up on DTDs. I haven't at all; what I *have* given up on is <!DOCTYPE ...> declarations. > Having said all that, > the spec is clear, you have to provide a SYSTEM identifier > for your DTD, i.e. a URL... why is this hard? -Tim URLs can break in too many ways. TMML users would be rightfully upset if they couldn't process their documentation because the SourceForge web site was down for maintenance, or if their network connection got unplugged. Document-relative SYSTEM identifiers are a maintenance nightmare; you have to keep too many copies of the public text around. PUBLIC identifier resolution would be great if it were universally supported, but it isn't. "SGML on the Web" is tremendously useful, but so is XML *off* the Web, and too many XML parsers fail to account for that. Most importantly: it's very difficult to ensure that the URI for a DTD will last as long as the documents that reference it. Remember the time that Netscape reorganized their web site and all the headline aggregators on the Web suddenly stopped working? This sort of thing is an unacceptable risk. --Joe English jenglish@f...