RE: [xml-dev] XML Schema views - are they possible?

["Michael Kay" <michael.h.kay@ntlworld.com>]

Title: XML Schema views - are they possible?

This is an excellent question and I'm not sure there's an easy answer. It's a concrete coding question that's directly related to the rather abstract debate we've been having over the last week about the need to apply multiple schemas to the same document at different stages of processing.

 

Over on xsl-list the other day we had someone who wanted to parameterize a schema, doing the equivalent of an #ifdef. I suggested writing the schema in the form of an XSLT stylesheet, using <xsl:param> and <xsl:if> to conditionally generate the operational schema based on supplied parameters. So in the middle of an xs:sequence, say, you could write

 

    <xs:element name="xyz" minOccurs="{if ($param='live') then 1 else 0}"/>

 

(This example is XSLT 2.0/XPath 2.0 but you could equally do it using 1.0)

 

Michael Kay

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From: Cheng, Andy [mailto:Andy.Cheng@ato.gov.au]
Sent: 27 August 2004 09:04
To: xml-dev@lists.xml.org
Subject: [xml-dev] XML Schema views - are they possible?

Dear XML Dev List,

Hello, my name is Andy and I'm a newbie to this forum. I am currently getting into the XML schema development and am having a problem (hope you guys can help me out). I'm wondering is there a possibility of having different XML Schema views (for reusability purposes). Here is an example of code:

<xs:complexType name="StatusType">
                <xs:all>
                        <xs:element name="StatusCode" minOccurs="0">
                                <xs:complexType>
                                        <xs:simpleContent>
                                                <xs:restriction base="tns:stringItemType">
                                                        <xs:minLength value="1"/>
                                                        <xs:maxLength value="10"/>
                                                </xs:restriction>
                                        </xs:simpleContent>
                                </xs:complexType>
                        </xs:element>
                        <xs:element name="StatusMessage" minOccurs="0">
                                <xs:complexType>
                                        <xs:simpleContent>
                                                <xs:restriction base="tns:stringItemType">
                                                        <xs:minLength value="1"/>
                                                        <xs:maxLength value="50"/>
                                                </xs:restriction>
                                        </xs:simpleContent>
                                </xs:complexType>
                        </xs:element>
                </xs:all>
</xs:complexType>

These two elements are optional. However, I want to reuse the complexType and change the 'StatusCode' element to mandatory ie change the value of 'minOccurs' to 1. What I have found so far is that I could use a 'restriction' element to change the value, hence the code:

<xs:element name="Status">
                                        <xs:complexType>
                                                <xs:complexContent>
                                                        <xs:restriction base="tns:StatusType">
                                                                <xs:all>
                                                                        <xs:element name="StatusCode">
                                                                                <xs:complexType>
                                                                                        <xs:simpleContent>
                                                                                                <xs:restriction base="tns:stringItemType">

                                                                                                        <xs:minLength value="1"/>

                                                                                                        <xs:maxLength value="10"/>

                                                                                                </xs:restriction>
                                                                                        </xs:simpleContent>
                                                                                </xs:complexType>
                                                                        </xs:element>
                                                                        <xs:element name="StatusMessage" minOccurs="0">
                                                                                <xs:complexType>
                                                                                        <xs:simpleContent>
                                                                                                <xs:restriction base="tns:stringItemType">

                                                                                                        <xs:minLength value="1"/>

                                                                                                        <xs:maxLength value="50"/>

                                                                                                </xs:restriction>
                                                                                        </xs:simpleContent>
                                                                                </xs:complexType>
                                                                        </xs:element>
                                                                </xs:all>
                                                        </xs:restriction>
                                                </xs:complexContent>
                                        </xs:complexType>
</xs:element>

What I would like to achieve is:
1. if I wanted to change the restriction values in the complexType, the change would ripple through to all elements using this complexType. However, this is not the case. When placing a 'restriction' element, in XMLSpy it duplicates all the elements from the complexType

2. If I didn’t want this element to be passed at all ie make maxOccurs ='0' (PS is this bad coding?), I don’t want the XML Schema to validate the element. After a few examples by putting the element in, the XML schema still does validate the element, although its not wanted.

Does anyone know how to get around this?? Or perhaps is there an alternative solution?

Thanks a lot!

Regards,

    Andy Cheng
Australian Taxation Office
INFORMATION COMMUNICATIONS & TECHNOLOGY
Software Development Quality & Productivity

andy.cheng@ato.gov.au  

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