[OSGeo-Standards] expath geo module

Peter Rushforth peter.rushforth at gmail.com
Thu Apr 8 16:10:28 EDT 2010


Hello OSGEO standards,

XPath 2.0 is a path grammar shared by the XQuery and XSLT languages
for accessing and selecting content within XML documents.

XSLT 1.0 left out major categories of functions, for example a math
library.  Library "modules" were defined by the community in the EXSLT
namespace, and  XSLT language implementations supported those
extensions, or not.  Many or most of the extensions defined by EXSLT
were functions that could be invoked in XPath expressions.

With time, many of the functions defined in EXSLT were incorporated
directly into the XSLT at version 2.0 of the language, and the need
for EXSLT has diminished.

With version 2.0 of XSLT, and version 1.0 of XQuery, a need for a
mechanism to specify language extensions that are shared by these
languages, and this need is being filled by the community at
EXPath.org.

Those languages excel at accessing and manipulating XML documents at
the highest granularity, however they don't directly address the
interactions or analysis needed by spatial programmers.

It has always been my hope that spatial functions would be
incorporated in the XSLT and XQuery languages.  A specification for
those functions that begins life at EXPath.org would have a good
chance for future adoption.  IMHO, the OGC Simple Features
specification should form that core.  EXPath is all about
specifications, but it is the first stop for implementers identifying
requirements.

To that end, if you are interested in standards-based spatial
processing in XSLT and/or XQuery (themselves standards!), I invite you
to join the discussion list here:
http://groups.google.com/group/expath , and discuss the expath geo
module with that community.  The initial scope of the proposal is
here:  http://expath.org/wiki/Geo.


Regards,
Peter Rushforth


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