Re: Attributes ordering

This is trickier.  In schema 1.0, this schema is not legal.  It violates 
what's known as the unique particle attribution constraint.  Reason:  if 
you give it the instance <a/><c/>, you would have to look ahead to realize 
that the <c/> needs to be matched against the element reference and not 
the wildcard.  Schemas with such ambiguities or lookahead requirements are 
illegal in schema 1.0.  Still, I can translate what this schema is trying 
to say:

* the <a/> must come first
* a <c/> must come last
* any number of additional things including <a/>'s and </c>'s can come in 
the middle. 

My point is: order always matters in a sequence the fact that the <any> 
tends to accept lots of different things may appear to obscure that, but 
in the end, sequences are always ordered.

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








Nataraj Ramalingam <Nataraj.Ramalingam@aricent.com>
Sent by: xmlschema-dev-request@w3.org
03/22/2007 02:48 PM
 
        To:     "Pete Cordell" <petexmldev@tech-know-ware.com>
        cc:     xmlschema-dev@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        Re: Attributes ordering



Does the same hold good, if wildcard is used? 

In the same mentioned example, instead of b, let's assume that a wildcard 
appears. 
========================================================================= 
<xs:complexType name="test">
       <xs:sequence>
               <xs:element name="a" type="xs:string"/>
                   <xs:any namespace="##other" processContents="lax" 
minOccurs="0" maxOccurs="unbounded"/>
               <xs:element name="c" type="xs:string"/>
       </xs:sequence>
</xs:complexType>

<xs:element name="test" type="test"/> 
==================================================================================== 

In this case, can there be instances of following possibilities, 
a,b,c           
a,c,b 
b,a,c         
a,c, b, b          where b is an element of some other namespace. 

I see that in some of the IETF protocols, only whenever wildcard is used, 
the order of elements inside a sequence seems strange. It simply allows 
any possibilities, almost breaking the expected sequence behavior. 
COuld this be clarified? 

Kind Regards, 
Nataraj. 




"Pete Cordell" <petexmldev@tech-know-ware.com> 
Sent by: xmlschema-dev-request@w3.org 
03/22/2007 11:27 PM 


To
Nataraj Ramalingam/CHE/HSS@HSS 
cc
<xmlschema-dev@w3.org> 
Subject
Re: Attributes ordering









Original Message From: "Nataraj Ramalingam" <Nataraj.Ramalingam@...>

>. I have one more doubt w.r.t ordering of elements.
> consider the following example.
> =====================================================
> <xs:complexType name="test">
>        <xs:sequence>
>                <xs:element name="a" type="xs:string"/>
>                <xs:element name="b" type="xs:string" minOccurs="0"/>
>                <xs:element name="c" type="xs:string"/>
>        </xs:sequence>
> </xs:complexType>
>
> <xs:element name="test" type="test"/>
> =====================================================
>
> Eventhough we use a sequence type here, does this mandate the order of
> elements in the instance to be only a,b,c.
> Or, since "b" is optional ( minOccurs=0 ), can it (should it, by any 
means
> )come after "c" in the instance? for example, can the ordering be a,c,b?


As it's a sequence, if b is present, then it must appear between a and c 
(i.e. the same order as specified in the definition).  (so a, b, c or just 

a, c.)

The xs:all construct for the order to be changed, but there are currently 
numerous restrictions on that.

HTH,

Pete.
--
=============================================
Pete Cordell
Tech-Know-Ware Ltd
for XML to C++ data binding visit
http://www.tech-know-ware.com/lmx/
http://www.codalogic.com/lmx/
=============================================






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Received on Thursday, 22 March 2007 20:01:31 UTC