Object-oriented serialization (Was Re: Some questions)

Rick Jelliffe ricko at allette.com.au
Sun Dec 5 17:45:48 GMT 1999

From: Matthew Gertner <matthew at praxis.cz>

>Dan Brickley wrote:
>> I believe it will be possible to annotate XML schemas with
>> for mapping into (generic or domain specific) application datamodels
>> such as RDF. I don't think it is right to expect the hard-pressed XML
>> Schema group to define all these mappings within that working group.
>I totally agree. As long as these considerations are being taken into
>account, I'm sure there will be plenty of people experimenting with
>various approaches. This will certainly lead to a better understanding
>of how to address these issues than simply mandating something that was
>worked out by a committee.

In this vein, schematron-rdf  at
generates RDF documents (currently with bogus XLinks, but you can
customize it easily) based on Schematron schemas. In this case, the
schema is not converted to RDF, rather the RDF shows which assertions in
the schema apply to each element in the instance.  This is a rather
different use for schemas: as programs for  automated annotation.

The thing that became immediately clear from working on it was that RDF
is good for arcs (relationships) but grammar-based schemas largely hide
these relationships (between elements, attributes, data) behind a few
generic but superficial types: containment, sequence, repetition.
Schematron assertions now allow a "role" attribute, for labelling
classes of arcs.

I think developers of other schema languages might also consider this
kind of thing too: that the connectors between particles of patterns
(e.g., compositors in the content models in a grammar-based schema
language) should have some role attribute (and documentation?) for
labelling their significance. For example, if element A must be follwed
by element B, to say why.  The nodes that conventional schemas define
(e.g. elements and attributes) are interesting, but the arcs between
them can also be very interesting for automatic annotation using RDF.

Rick Jelliffe

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