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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Architectural Forms and XAF
 > >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. > > I don't follow this. You seem to be saying that the limimitations on > AF transformation power somehow helps. Please explain. After you have transformed a document by means of an *arbitrary* transformation process (such as an XSLT-driven, DSSSL-driven, or program-driven transformation process), you can't necessarily tell whether some particular information set was present in the untransformed document. The transformation process is always suspect: does it respond appropriately to all of the possible information configurations? Are all of the possible input configurations accounted for? The input document is also suspect: did it really have the information set I was looking for in the output of my transformation process? (No transformation process can correct all possible malformations in the input.) When information interchange fails, and when information interchange depends on transformation processes of arbitrary capabilities, it's practically impossible to point the finger of blame at the party whose software was actually responsible for the failure. If we can't point the finger of blame, we can't have reliable, vendor-neutral information interchange. Accountability is vital. The essential thing that enables vendor-neutral information interchange is conformance to rigorous formal models. Such models are like contracts between information producers and software producers. Nobody can write software that understands just any old way of constructing data; it's impossible. Models are essential. I think you agree with this. On the other hand, diversified industrial communities cannot be expected to make all their business messages absolutely conform to a given model. I think you agree with this point, too. Your answer appears to be to provide transformation programs between the variant dialects used to express a given information set. I'm saying that your approach will work for a while, but it will become a black hole for resources and it will be unreliable. Firstly, information interchange is not well served by the necessity of writing so many transformation programs; such programs are costly to create and maintain. Secondly, transformation programs contain errors which are practically impossible to discover and fix in advance of the time when they hurt somebody. So, right at the outset, we will lose information, which will give XML a bad name, and will make rigid old EDI look good by comparison. Thirdly, transformation programs are brittle; they generally require maintenance (which introduces more errors) whenever something changes. We've just been through the costly mess caused by the Y2K bug; does any serious business manager really welcome the idea of revising a huge amount of business-model-specific code every time his industry must, as a whole, deal with some involuntary change in the business climate, such as a change the governing legislation? I think not. Architectural forms provide a reasonable solution to all of constraints that reality imposes on the problem of supporting reliable, vendor-neutral information interchange. I'd be delighted if anyone comes up with a better solution than architectural forms. Throwing a welter of transformation programs at the problem is decidedly *not* a better solution, from a purely economic perspective, from a reliability perspective, and from a "marketability of XML" perspective. Failure to adopt the architectural forms paradigm also condemns us all to a world in which vocabulary-specific semantic engines cannot mature into reliability by virtue of their ability to serve diverse markets. This would be perhaps the biggest single blow to the future reliability of vendor-neutral information interchange. Of course, if we're willing to accept the idea that a single company will be responsible for the reliability of all information interchange between everybody, we don't need to worry about the above-described triangle of constraints (the need for rigorous models, the need to support diversity, and the need to cope with constant change at the lowest possible cost). But then we'd have other problems to worry about, and there would be no need for XML or other industry standards at all, would there? -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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