> I would like to support variable content in certain elements
> of my schema based on the elements belonging to a common type
> hierarchy. I want to make sure that the approach I take is:
>
> * Well suited for binding to programming languages using popular
> data binding tools such that the resulting bindings allow
> operating on the variable content based upon their common type
> (poetntially abstract)
Can't advise on data binding, I'm not up to date with what the tools
support.
> * Well suited for processing instance documents by XSLT such that
> adding new types to the variable content hierarchy does not
> require modifying the XSLT for processing the common elements and
> attributes of the variable content base type
>
XSLT 2.0 with schema-awareness can handle both type hierarchies and
substitution groups. For example you can match all elements in the
substitution group of event using
<xsl:template match="schema-element(event)">
and you can match all elements of type event-type using
<xsl:template match="element(*, event-type)">
and of course in both cases you can match any name at any level of the
hierarchy.
I would certainly use substitution groups where they make sense: they seem
closer to the semantics of the data model.
Michael Kay
http://www.saxonica.com/
