[DFDL-WG] DFDL wildcards with dimension

[Suman Kalia]

Putting xsd:any inside xsd:choice is not desirable.. the following schema 
( copied for reference from below) would validate any content under x.  It 
is as good as defining  element x of type xsd:any with 
maxOccurs='unbounded"

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

 <xsd:element name="x"> 
 <xsd:complexType> 
  <xsd:choice maxOccurs='unbounded'> <!-- array of choice --> 
   <xsd:element name="name"/> 
   <xsd:element name="address"/> 
   <xsd:any processContents="lax"/> 
  </xsd:choice> 
</xsd:complexType> 
</xsd:element> 

</xsd:schema> 

If there are good practical uses case scenarios that we know for having 
xsd:any with maxOccurs > 1 inside sequence ( ordered or not)  then we 
should allow it otherwise it just adds unnecessary complexity to the 
model, parsers, tools for a functionality that no one might require/use  . 
. 

Suman Kalia
IBM Toronto Lab
WebSphere Business Integration Application Connectivity Tools 
Tel : 905-413-3923  T/L  969-3923
Fax : 905-413-4850 T/L  969-4850
Internet ID : kalia at ca.ibm.com



Mike Beckerle <beckerle at us.ibm.com> 
Sent by: dfdl-wg-bounces at ogf.org
11/21/2007 01:44 PM

To
dfdl-wg at ogf.org
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Subject
[DFDL-WG] DFDL wildcards with dimension







I did some investigation. 

1) xs:any wildcards are not allowed inside xs:all groups at all. 

2) The schema below is valid, and admits the instance document following 
it: 

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

 <xsd:element name="x"> 
 <xsd:complexType> 
  <xsd:sequence> 
   <xsd:element name="name"/> 
   <xsd:element name="address"/> 
   <xsd:any processContents="lax" minOccurs='0' maxOccurs='unbounded'/> 
  </xsd:sequence> 
</xsd:complexType> 
</xsd:element> 

</xsd:schema> 

Here's the instance: 

<?xml version="1.0"?> 
<x> 
<name/> 
<address/> 
<foo/> 
<bar/> 
<quux/> 
<frobboz/> 
</x> 

3) Note however, the only way to create an XML Schema which will validate 
both the instance above and the one below where the order is all 
scrambled, is an array-of-choice schema: 

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

 <xsd:element name="x"> 
 <xsd:complexType> 
  <xsd:choice maxOccurs='unbounded'> <!-- array of choice --> 
   <xsd:element name="name"/> 
   <xsd:element name="address"/> 
   <xsd:any processContents="lax"/> 
  </xsd:choice> 
</xsd:complexType> 
</xsd:element> 

</xsd:schema> 

This array-of-choice schema will accept this instance document also: 

<?xml version="1.0"?> 
<x> 
<foo/> 
<address/> 
<bar/> 
<name/> 
<quux/> 
<frobboz/> 
</x> 

The above array-of-choice schema obviously will also accept things where 
there are multiple name and address entries, which is undesirable, but the 
XPath expressions x/name and x/address will still work. 

<?xml version="1.0"?> 
<x> 
<address/> 
<address/> 
<foobar/> 
</x> 

Implications for DFDL: I suggest we should allow dimension on any 
wildcards because this unordered sequence DFDL fragment: 

<xsd:sequence dfdl:ordered="false"> 
    <xsd:element name="name"/> 
    <xsd:element name="address"/> 
    <xsd:any id="unknown" processContents="lax" minOccurs='0' 
maxOccurs='unbounded'/> 
 </xsd:sequence> 

describes something quite useful which otherwise requires an array of 
choice to model. 

Array-of-choice is generally undesirable as a model because it loses the 
cardinality information that says that name is required and address is 
required and there can be exactly 1 instance of each. 

...mikeb 

Mike Beckerle
STSM, Architect, Scalable Computing
IBM Software Group
Information Platform and Solutions
Westborough, MA 01581
direct: voice and FAX 508-599-7148
assistant: Pam Riordan 
                 priordan at us.ibm.com 
                 508-599-7046
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