[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Architectural Forms and XAF
> [Steve Newcomb on AFs] > >When looking at such an element, select the attribute that > >corresponds to the meta DTD you're interested in interpreting the > >element as conforming to; the value of that attribute is the tagname > >for all purposes of that meta DTD.) [Sean McGrath:] > In other words, (as I have said before, years ago > on comp.text.sgml), there > is nothing "meta" about meta DTDs. > They are essentially, a device for > simple one-to-one mappings of element > type name to element type name with some > extra bells on. > > In my world, this facility fails the "so what" > test. > > Oh how I wish the real world were so simple, > that a basic mapping system sufficed to > get real work done. > > I cannot understand why people think > that this capability solves so many > real world problems. It doesn't in > my experience. > > Simple mapping of source elememt type name > to destination element type name makes > up about 0.00001% of what I do in > SGML/XML processing work. The > other 99.00009% is made up of re-arranging > sub-trees, collapsing strucures, expanding > structures, hoisting content to attribute, > dropping attributes to data content etc. etc. > > The declarative syntax of XSLT is a lot > closer to the money for my work as it > goes beyond simple element mapping and > sub-tree pruning. Not that XSLT does > not have its problems from my perspective > but that is a different rant:-) Sean, somehow you've completely missed the point of AFs. AFs are not about general transformations. If you try to use AFs for general transformations, you're exactly right: you'll quickly discover that they don't do much for you. They don't do nearly enough! Now here's the real point. Without AFs, there are only two choices, in all cases where all the players in an industry must communicate freely with each other: (1) Everybody has to use the same DTD or Schema (which ain't gonna happen for reasons too obvious to mention here), or (2) Everybody uses different DTDs, and, for N DTDs, there must be roughly N-squared transformation specifications to convert between them. This situation is, if anything, even more untenable than the "everybody uses the same DTD" paradigm, because if any one DTD changes, N minus 1 transformation specifications must also change. The cost of maintaining the ability to interchange information throughout the industry increases geometrically as the number of different participants, each of whom has his own DTD. It's economically crazy. Large and diverse industries must be able to communicate, control of the syntax of messages must be distributed, and change must be accommodatable at low (or no) cost. AFs provide a paradigm in which, *precisely because AF transformations are so bloody limited in their transformational power*, everybody gets to control their own DTDs, and, at the same time, everybody's messages are interpretable and validatable as industry-standard messages. No transformation specifications are required. If the industry-standard meta-DTD changes, all the necessary transformation code is automatically updated (since there is no such code). If somebody needs to change their own DTD, it causes no problem as long as they don't prevent their messages from conforming to the inherited industry-standard DTD. -Steve -- Steven R. Newcomb, President, TechnoTeacher, Inc. srn@t... http://www.techno.com ftp.techno.com voice: +1 972 517 7954 fax +1 972 517 4571 Suite 211 7101 Chase Oaks Boulevard Plano, Texas 75025 USA *************************************************************************** This is xml-dev, the mailing list for XML developers. To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev List archives are available at http://xml.org/archives/xml-dev/ ***************************************************************************
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