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W.E Perry wrote:
> Within all of this difference, where does the basis for interoperability lie? In the XML
> syntax of the documents themselves. It is precisely because XML documents can be used by
> different processes as the basis for entirely different function that such a document
> can be the nexus of interoperability between dissimilar, autonomous, and perhaps
> mutually anonymous processes. A datamodel, however, is nothing more than the abstraction
> of the particular data instantiation built on a particular occasion on the output of a
> particular parse of a given XML document.
let me just point out that a data model too can be shared, and form the
basis of interoperability. as can an event model like SAX. and let's not
have any illusions about these artifacts of the parse process - they are,
and should be, designed to make the processing, whatever processing we're
looking at here, as easy and effective as possible. it is not the main
purpose of parsed objects to represent the document as truthfully as
possible, but to facilitate processing. the document is the document is
the document, a data model is a model and nothing but a model.
there. now if i want to integrate, ie make interoperable, processes of
which i know more than that they use XML in some form, i might choose to
pass in-memory DOM objects (parse artifacts) or configure a SAX event
handling chain that starts and finishes with a document.
where's the danger to XML?
example:
for my o:XML web site, i'm using both static and dynamically generated
docbook documents that are XSL-transformed into html and pdf. for dynamic
pages the processing happens in two stages - an o:XML program file is
evaluated which results in an XML result document, which is then processed
by an XSLT engine. at the moment this is achieved by two separate Ant
tasks, both producing documents.
i could just as well feed the output of the first process directly into
the second, seeing both applications are capable of using the same data
model.
pros and cons? - tightly versus loosely coupled processes is a design
decision which should be based on fitness for purpose, not dogma.
regards,
/m
Martin Klang
http://www.o-xml.org - the object-oriented XML programming language
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