xml-dev - Re: Query Languages for XML

["W. Eliot Kimber" <eliot@isogen.com>]

Any query language for XML would, by necessity, be a syntax for
accessing the properties of XML objects (where the object schema would
come from either the SGML property set, the DOM, or something derived
from one or both).  Certainly SDQL provides this. Any new language
would, I think, mostly be an exercise in syntax definition, most of
which is already inherent in the development of XSL (which is nothing
more than a language for applying processes to the results of queries on
XML groves).

>From another point of view, it's not possible to have *an* XML query
language because there are too many different ways that you might want
to access XML data: as nodes in groves ala SDQL, as full text using some
full-text index, as semantic-specific objects using some domain-specific
query mechanism, etc.

A language like SDQL coupled with an XML property set (that is, the
subset of the SGML property set needed to represent XML documents)
provides a complete set of operations for querying XML documents
represented as groves.  These operations can be used either as
primitatives from which more specialized languages are created or as a
design spec that drives the development of a new syntax for expressing
the equivalent queries.

So my question is: is what is desired only a new *syntax* or is there a
requirement for a fundamentally different query mechanism?  Or have I
entirely missed the point of the original question?

Cheers,

Eliot

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