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Danny Vint writes:
I have the following situation:
1) Base industry standard schema (ACRD)
2) A schema that imports the ACRD schema (to reuse data types and
some elements) that defines my organizations new elements and
aggregates (ACME)
3) A schema that redefines #1 ACRD to modify existing elements and
aggregates to include my new ACME elements.
I then have a docuemnt instance the references #3.
Xerces and XSV say my document and schemas are valid.
XSV accepts your package because it never processes a namespaced
schema document more than once if it can avoid it, so the nested,
potentially problematic, import in (2), does not cause a problem
because the ACRD schema document has already been processed (during
the processing of (3), so the 'schemaLocation' of the import in (2) is
ignored).
This is conformant behaviour, because the REC says that
'schemaLocation' on <xs:importis a hint, which need not be followed.
But it's not _required_ behaviour, for better or worse.
I'd like to see a way for users to mandate such behaviour. . .
ht
- --
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: ht (AT) inf (DOT) ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
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Danny Vint writes:

[not happy depending on optionality of following 'schemaLocation' hint]

Let's go back to your requirements.

Here is a minimal example of your (1) -- (3):

(1) ACRD.xsd:
<xs:schema targetNamespace="http://www.example.com/ACRD">
<xs:complexType name="ACType">
<xs:sequence>
<xs:element name="AElt1"/>
<xs:element name="AElt2"/>
</xs:sequence>
</xs:complexType>

<xs:simpleType name="ASType">
<xs:restriction base="xs:token">
<xs:enumeration value="red"/>
<xs:enumeration value="white"/>
<xs:enumeration value="blue"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>

(2) ACME.xsd:
<xs:schema xmlns:ac="http://www.example.com/ACRD"
targetNamespace="http://www.example.com/ACME">
<xs:import namespace="http://www.example.com/ACRD"
schemaLocation="ACRD.xsd"/>
<xs:element name="MyE" type="ac:ASType"/>
</xs:schema>

(3) AA.xsd:
<xs:schema targetNamespace="http://www.example.com/ACRD"
xmlns:ac="http://www.example.com/ACRD"
xmlns:my="http://www.example.com/ACME">
<xs:import namespace="http://www.example.com/ACME"
schemaLocation="ACME.xsd"/>
<xs:redefine schemaLocation="ACRD.xsd">
<xs:complexType name="ACType">
<xs:complexContent>
<xs:extension base="ac:ACType">
<xs:sequence>
<xs:element ref="my:MyE"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:redefine>
</xs:schema>

So, as you already observed, this works with XSV, but not with all
tools.

The problem arises when ACRD.xsd is processed twice, producing two
conflicting definitions of ACType.

So, to fix this, we want to prevent the double processing. Proposed
solution (I don't have access to the tool you're having trouble with):
remove the offending hint.

That is, change ACME.xsd:
<xs:schema xmlns:ac="http://www.example.com/ACRD"
targetNamespace="http://www.example.com/ACME">
<xs:import namespace="http://www.example.com/ACRD"/>
<xs:element name="MyE" type="ac:ASType"/>
</xs:schema>

This is still a valid schema document. And now processing AA.xsd
should not provoke any conflicts, as only the redefined type
definition will be created.

Hope this helps,

ht
- --
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: ht (AT) inf (DOT) ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
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