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Re: xs:choice and xs:sequence question

From: Pete Cordell <petexmldev@tech-know-ware.com>
Date: Thu, 12 Jan 2006 09:09:56 -0000
Message-ID: <001801c61758$1b204b60$b100a8c0@RW>
To: <d_a_carver@yahoo.com>, <xmlschema-dev@w3.org>

(In addition to George's comment), what you have here is a Unique Particle 
Attribution Constraint (UPAC) violation.  I think it's Appendix H of Schema 
part one that explains this better, but basically when encountering 
'DescriptionMessage' it's not immediately obvious to a validator whether it 
belongs to the first sequence or the second.

A simple fix (if it doesn't violate your idea of aesthetics too much!) would 
be to move 'ApplicationReasonCode' to the top of the second sequence.  Then 
it becomes unambiguous about which leg of the choice is being parsed.

HTH,

Pete.
----- Original Message ----- 
From: "David Carver" <d_a_carver@yahoo.com>
To: <xmlschema-dev@w3.org>
Sent: Wednesday, January 11, 2006 3:37 PM
Subject: xs:choice and xs:sequence question


>
> I have the following complexType coded:
>
>   <xs:complexType name="ProcessingOutcomeMessage">
>       <xs:choice>
>           <xs:sequence>
>               <xs:element ref="DescriptionMessage" minOccurs="0" 
> maxOccurs="unbounded" />
>               <xs:element ref="MessageReasonCode" minOccurs="0" />
>           </xs:sequence>
>           <xs:sequence>
>               <xs:element ref="DescriptionMessage" type="Description" 
> minOccurs="1" maxOccurs="unbounded" />
>               <xs:element ref="MessageReasonCode" type="MessageReasonCode" 
> minOccurs="1" />
>               <xs:element ref="ApplicationReasonCode" 
> type="ApplicationReasonCode" minOccurs="1">
>                   <xs:annotation>
>                       <xs:documentation 
> source="http://www.starstandard.org">Contains a software specific 
> application reason code.</xs:documentation>
>                   </xs:annotation>
>               </xs:element>
>           </xs:sequence>
>       </xs:choice>
>   </xs:complexType>
>
> It validates fine if using Xerces J 2.7.0 or XSV 2.5.  However, 
> Microsoft's XML, XML Spy 2006 SP2, and Oxygen complain about 
> DescriptionMessage being defined twice, even though they are in seperate 
> sequence groups.
>
> What I want to do is require DescriptionMessage, MeassageReasonCode if 
> there is an ApplicationReasonCode, if there isn't an 
> ApplicationReasonCode, then DescriptionMessage and MessageReasonCode are 
> optional.
>
> Any help would be appreciated.
>
> Thanks.
>
> Dave
>
--
=============================================
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 Thursday, 12 January 2006 09:11:03 GMT

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