• From: "G. Ken Holman" <gkholman@C...>
• To: xml-dev@l...
• Date: Wed, 19 Sep 2007 09:12:29 -0400

At 2007-09-19 18:13 +0530, Mukul Gandhi wrote:
>    I want to validate an XML instance like following with W3C XML Schema.
>
><OBJECTS>
>   <!-- A & Bs in any order and unbounded. B can be before A also. -->
>   <A>ddjhfj</A>
>   <B>hghgh</B>
>   <!-- more A & Bs -->
></OBJECTS>

Sounds like a simple alternation.

>I want a Schema like (which is invalid) following.
>
><xs:element name="OBJECTS">
>    <xs:complexType>
>        <xs:all>
>           <xs:element name="A" type="xs:string" maxOccurs="unbounded" />
>           <xs:element name="B" type="xs:string" maxOccurs="unbounded" />
>        </xs:all>
>     </xs:complexType>
></xs:element>
>
>But this is wrong, because in this Schema maxOccurs can be 0 or 1.

I'm not sure what you mean by that.

Do you mean by trying <xs:all> that it is a requirement to have at 
least one of each?

>Could somebody please suggest a Schema for this requirement.

Since you are looking for an unbounded quantity, a simple alternation 
should work if either is optional in the whole:

T:\ftemp2>type mukul.xml
<OBJECTS>
   <!-- A & Bs in any order and unbounded. B can be before A also. -->
   <A>ddjhfj</A>
   <B>hghgh</B>
   <!-- more A & Bs -->
</OBJECTS>

T:\ftemp2>type mukul.xsd
<?xml version="1.0" encoding="US-ASCII"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:element name="OBJECTS">
   <xsd:complexType>
     <xsd:choice maxOccurs="unbounded">
       <xsd:element name="A" type="xsd:string"/>
       <xsd:element name="B" type="xsd:string"/>
     </xsd:choice>
   </xsd:complexType>
</xsd:element>

</xsd:schema>

T:\ftemp2>w3cschema mukul.xsd mukul.xml
Xerces...
No validation errors.
Altova...
The XML data is valid

T:\ftemp2>


If, however, you have a requirement that at least one of each are 
required and can be in any order, then things get a bit more complex:

    ( A+, B, (A | B)* ) | ( B+, A, (B | A)* )

T:\ftemp2>type mukul.xml
<OBJECTS>
   <!-- A & Bs in any order and unbounded. B can be before A also. -->
   <B>hghgh</B>
   <A>ddjhfj</A>
   <B>hghgh</B>
   <A>ddjhfj</A>
   <A>ddjhfj</A>
   <B>hghgh</B>
   <B>hghgh</B>
   <!-- more A & Bs -->
</OBJECTS>

T:\ftemp2>type mukul.xsd
<?xml version="1.0" encoding="US-ASCII"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:element name="OBJECTS">
   <xsd:complexType>
     <xsd:choice>
       <xsd:sequence>
         <xsd:element ref="A" maxOccurs="unbounded"/>
         <xsd:element ref="B"/>
         <xsd:choice minOccurs="0" maxOccurs="unbounded">
           <xsd:element ref="A"/>
           <xsd:element ref="B"/>
         </xsd:choice>
       </xsd:sequence>
       <xsd:sequence>
         <xsd:element ref="B" maxOccurs="unbounded"/>
         <xsd:element ref="A"/>
         <xsd:choice minOccurs="0" maxOccurs="unbounded">
           <xsd:element ref="B"/>
           <xsd:element ref="A"/>
         </xsd:choice>
       </xsd:sequence>
     </xsd:choice>
   </xsd:complexType>
</xsd:element>

<xsd:element name="A" type="xsd:string"/>
<xsd:element name="B" type="xsd:string"/>

</xsd:schema>

T:\ftemp2>w3cschema mukul.xsd mukul.xml
Xerces...
No validation errors.
Altova...
The XML data is valid

T:\ftemp2>

The interleave concept in RELAX-NG would be really helpful here:

   ( A+ & B+ )

I hope this helps.

. . . . . . . . . . .Ken

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• References:
  • <xs:all> with different elements in any order
    • From: "Mukul Gandhi" <gandhi.mukul@g...>