Query Languages for XML

W. Eliot Kimber eliot at isogen.com
Mon Nov 17 22:40:57 GMT 1997


At 05:00 PM 11/17/97 -0500, Jonathan Robie wrote:
>I don't know much about SDQL. It is part of the DSSSL standard - is it
>scheme based? Is it procedural? Is it based on SGML/XML document structure?
>Can it be used for queries of types 1 and 2?

SDQL is simply that part of the larger DSSSL expression language that
enables the accessing of properties of nodes in groves and the navigation
of groves.  It uses the same syntax as the rest of DSSSL, that is a Scheme
variant.  It is based on the basic grove data model (nodes and their
properties) but has some built-in functions related to SGML (e.g., "gi",
"att-string", etc.).  All the built-in functions are or can be defined in
terms of primitives (e.g., node-property).  It includes some basic
string-matching functions but does not attempt to provide any sort of
complete full-text facility (which would be outside the stated scope of
DSSSL in any case).

Note, however, that the syntax is largely arbitrary: what's important are
the semantics of grove access.  Thus, you can expect XSL to include the
functional equivalent (more or less) of SDQL even though it may provide an
alternative syntax.

Cheers,

E.
--
<Address HyTime=bibloc>
W. Eliot Kimber, Senior Consulting SGML Engineer
Highland Consulting, a division of ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 95202.  214.953.0004
www.isogen.com
</Address>

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