W3C home > Mailing lists > Public > xmlschema-dev@w3.org > January 2007

Re: Interaction of explicit attributes and wildcards

From: Pete Cordell <petexmldev@tech-know-ware.com>
Date: Wed, 24 Jan 2007 18:12:53 -0000
Message-ID: <002c01c73fe3$4ed58290$8f00a8c0@Codalogic>
To: "Michael Kay" <mike@saxonica.com>, "'Henry S. Thompson'" <ht@inf.ed.ac.uk>
Cc: <xmlschema-dev@w3.org>

Original Message From: "Michael Kay" <mike@saxonica.com>
>
> This situation can't occur with elements because UPA prevents an element
> particle overlapping with an element wildcard particle. There's no
> corresponding rule for attributes: the explicit attribute wins over the
> attribute wildcard. It's not clear why the rules for elements/attributes
> here are asymmetric.

I haven't finished reading the proposed XSD 1.1 yet (don't spoil the ending 
for me!), but presumably this will change under XSD 1.1 when the UPA is 
relaxed.  Then elements with maxOccurs = 0 will be treated as nothing rather 
than prohibited in much the same way as attributes with use='prohibited' and 
the same situation will arise.

> Rather than making this case an error (an invalid schema), it would seem
> more helpful to define the rules so that use="prohibited" means what it
> says: an attribute of this name is prohibited, despite the presence of a
> wildcard that would otherwise permit it.

Makes sense to me.

Pete.

> Michael Kay
> http://www.saxonica.com/
>
>
>> -----Original Message-----
>> From: xmlschema-dev-request@w3.org
>> [mailto:xmlschema-dev-request@w3.org] On Behalf Of Henry S. Thompson
>> Sent: 24 January 2007 13:49
>> To: srinivasarao vegunta
>> Cc: xmlschema-dev@w3.org
>> Subject: Re: Interaction of explicit attributes and wildcards
>>
>>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> [Please _don't_ use HTML-format mail to public lists -- not
>> all of us are using Outlook!]
>>
>> srinivasarao vegunta writes:
>>
>>  According to several schema processors, (Saxon, Xerces, MS
>> .NET), the
>>  following instance:
>>
>>  <e att1="banana"/>
>>
>>  is valid against the following schema:
>>
>>  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
>>
>>  elementFormDefault="qualified"
>> attributeFormDefault="unqualified">
>>  <xs:complexType name="B">
>>
>>  <xs:sequence/>
>>
>>  <xs:attribute name="att1" use="optional" type="xs:decimal"/>
>>
>>  <xs:anyAttribute namespace="##local"
>>
>>  processContents="skip"/>
>>
>>  </xs:complexType>
>>
>>  <xs:complexType name="R">
>>
>>  <xs:complexContent>
>>
>>  <xs:restriction base="B">
>>
>>  <xs:attribute name="att1" use="prohibited"/>
>>
>>  <xs:anyAttribute namespace="##local"
>>
>>  processContents="skip"/>
>>
>>  </xs:restriction>
>>
>>  </xs:complexContent>
>>
>>  </xs:complexType>
>>
>>  <xs:element name="e" type="R"/>
>>
>>  </xs:schema>
>>
>>  But change the element declaration to <xs:element name="e"
>> type="B"/>, and
>>  validation fails, saying that "banana" is not a valid
>> xs:decimal (the same
>>  set of schema processors agree on this).
>>
>>  Surely the element cannot be a valid instance of R unless it
>> is also a valid
>>  instance of B?
>>
>>
>> You have hit on one of the areas where the Schema REC fails
>> to live up to its own promise that restrictions accept
>> subsets of their base.
>>
>> The behaviour you describe is conformant, it follows all the
>> explicit rules in the spec. for checking valid restrictions.
>> It's just that those rules aren't quite 'right'.
>>
>> The XML Schema WG expects to fix this problem in v1.1.
>>
>> ht
>> - --
>>  Henry S. Thompson, HCRC Language Technology Group,
>> University of Edinburgh
>>                      Half-time member of W3C Team
>>     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44)
>> 131 650-4440
>>             Fax: (44) 131 650-4587, e-mail: ht@inf.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] -----BEGIN PGP SIGNATURE-----
>> Version: GnuPG v1.2.6 (GNU/Linux)
>>
>> iD8DBQFFt2PbkjnJixAXWBoRArzHAJsFzcU5+hgsZ61Wsiq7Ue2dTu8n4QCeJKNC
>> FFyL2hvq4zjr4bzRiZuf31I=
>> =pVkY
>> -----END PGP SIGNATURE-----
--
=============================================
Pete Cordell
Tech-Know-Ware Ltd
for XML to C++ data binding visit
http://www.tech-know-ware.com/lmx
(or http://www.xml2cpp.com)
=============================================
Received on Wednesday, 24 January 2007 18:13:16 GMT

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