RE: Impact of xs:redefine

Isn't this covered by some of the consistency rules for the types? And
if not, we should specify it as a consistency rule and not as a rule on
how schemata are imported...

Best regards
Michael

> -----Original Message-----
> From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
> request@w3.org] On Behalf Of Kay, Michael
> Sent: Sunday, January 04, 2004 11:11 AM
> To: public-qt-comments@w3.org
> Subject: Impact of xs:redefine
> 
> 
> I think there is probably a need, in both XSLT 2.0 and XQuery 1.0, to
> place
> constraints on the use of xs:redefine in imported schemas.
> 
> The specifications generally assume that schema components are
identified
> uniquely by their expanded QName. However, if one query module imports
> schema1.xsd, and another query module imports schema2.xsd, and
schema1.xsd
> redefines schema2.xsd, then the two query modules are using different
> definitions of the same named types. This means that when a node is
> annotated with a QName, we don't know whether it was validated against
the
> original type or the redefined type.
> 
> There don't appear to be any existing rules that cover this.
> 
> In XSLT 2.0, I think it's reasonably easy to fix, because (a) the set
of
> imported types is the same in all stylesheet modules, and (b) we
define
> the
> semantics of xsl:import-schema in terms of importing a single
composite
> schema, which means that the redefined definitions are used
throughout.
> The
> only problem that arises is when source documents arrive that have
been
> validated against an "unredefined" version of the schema; these may
carry
> type annotations that are inconistent with the redefined types. This
is
> essentially the same problem as occurs when different versions of a
schema
> are used in xsl:import-schema and in source document validation, and
we
> can
> disallow it under the same provision.
> 
> In XQuery 1.0 it's a little more difficult, because each query module
has
> its own static context, but it can still be done under the rule that
all
> versions of a single type definition must be consistent. This amounts
to
> saying (a) it's not allowed for one module to import schema1.xsd and
for
> another module to import a schema that redefines schema1.xsd, and (b)
the
> implementation must (?) detect when this happens. But is this
restriction
> acceptable?
> 
> Michael Kay
>

Received on Sunday, 4 January 2004 15:17:19 UTC