xml-dev - APIs ... Re: CDATA by any other name... (was The raw and the cooked)

[Paul Prescod <papresco@technologist.com>]

David Brownell wrote:
> 
> > I find it odd that we can have "standard APIs" for the full complexity of
> > relational data, and probably eventually for object database data, but it
> > is perceived to be impossible to do the same for the parse tree of XML
> > data. I mean it is just annotated tree structures: it shouldn't be rocket
> > science (but neither is it trivial).
> 
> If it's just annotated tree structures, I'd say that's what DOM is for!
> Or should be, warts and XML Data Model conformance aside.

That's right. If the DOM were done right, it would be what I would call a
"standard API" for XML data. It wouldn't be appropriate for the the 
abstract, arbitrarily complex data models built on top of XML. It would
be for the XML data itself. But the DOM is quite far from that. It is
geared towards scripters and is thus not general enough for the problems
I would like to solve.

> Why would I say no "standard API" would exist for the rest?  There are
> thousands (conservatively!) of data/object models specialized to each
> application.  While a tree (or grove, or graph) would seem isomorphic
> with any such model, it's not necessarily optimal for any one of them.

That's true. Similarly, a relational data model is not the only API in
every application that *uses* a relational model, but you could say that a
single relational database API (ODBC) is usually sufficient. That's all I
would hope to replicate.

> Similarly, "pure data" is a model many of us have been moving folk away
> from over the last decade.  It's critical for interoperability between
> system components (e.g. over the web, with XML!), but raw data must be
> joined with methods (or other code) before it's used.  Ergo, "objects"
> instead of APIs to data; classes not structs.

Yes, there is an impedence mismatch that must be overcome between the XML
data model and your application's data model, just as there is a mismatch
between OO programs and relational data. A standard XML-level API (or
perhaps
two, one event driven and one tree driven) would help us to overcome that, 
not perpetuate it.

 Paul Prescod  - http://itrc.uwaterloo.ca/~papresco

"The new revolutionaries believe the time has come for an aggressive 
move against our oppressors. We have established a solid beachhead 
on Friday. We now intend to fight vigorously for 'casual Thursdays.'
  -- who says America's revolutionary spirit is dead?



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