xml-dev - Parser question...

[Kim Covil <kimc@ned.dem.csiro.au>]

I am hoping this is the correct place to post a couple of questions
I have at present...

We (my boss and I) are currently developing a metadata system using
xml to describe and reference the various different data sets we 
have, into a single body of information... The idea is to have a
single description file for each resource (document, GIS dataset, 
3d model) that enables us to index all our resources and create
multiple views of each resource from the the description files...

Currently we are using an SGML parser to parse the xml description
files and a perl script to walk through the parsed tree and output
whichever view of the data is required (HTML, VRML, image data...)
The perl interface we are using is SGML::SPGrove written by 
Ken MacLeod to link with James Clark's SP...

We are reasonably happy with the way this works although a touch
more speed would be helpful as the views the scripts create are
created on the fly... I have been wondering whether there are any
tools out there that will 'cache' the parsing of a DTD... As all
our resources use the same DTD, each time a view is created the
xml file is parsed... the DTD is referenced... the DTD is parsed 
and then the xml is validated... 

It seems to me that we should be able to reuse the middle bit... 
Are there any tools that treat a DTD as an input to create a 
validating parser...? I am think of the sort of thing lex and yacc 
do...

That was my first question... My second is more of a clarification...
I am still a little unsure of the use of NOTATIONs... I think
they would be perfect for encapsulating data that will be stored
in the xml that we are going to hand to a 'handling' package to
produce the resource... ie:

<!NOTATION arcinfo...
<!NOTATION vulcan...
<!NOTATION [others]...

<!ELEMENT gisdata (parameters,type)>
<!ATTLIST gisdata package NOTATION (arcinfo|vulcan|...) #REQUIRED>
<!ELEMENT parameters (#PCDATA)>
<!-- the format of the data in parameters depends on the package
     of the gisdata element and will basically be a parcel of
     parameters to be handed to the package such that it will
     return the required object/resource -->

Is this sort of thing correct usage of NOTATIONs or should this be
done using PIs and if so could someone show me how it would be
done...?

Cheers,

Kim
--
====================================================================== 
Kim Covil - Australian Geodynamics CRC   E-mail: kimc@ned.dem.csiro.au 
            CSIRO Exploration & Mining   Tel: +61 8 9284 8425   ,-_!\
            PO Box 437, Nedlands,        Fax: +61 8 9389 1906  /     \
            Western Australia  6009                            *_,-._/   
=================================================================== v 
   Please direct all personal e-mail to kimbotha@cygnus.uwa.edu.au

     

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