xs:any in xs:all tag for xsd

Question

I have a scenario where I need a xsd which is used for validating few bunch of xml's which have few things in common. For example,

xml1:

<myXml1>
<myTag>
<someTag>..</someTag>
<requiredTag>..</requiredTag>
<someotherTag>..</someotherTag>
</myTag>
<myXml1>

xml2:

<myXml1>
<myTag>
<requiredTag>..</requiredTag>
<otherTag>..</otherTag>
</myTag>
<myXml1>

I am in need of a common xsd so as to validate both the xmls's which have "requiredTag" in common and read its value.

I tried using <xs:any> but it is supported only in xs:sequence and not in xs:all. My requiredTag can be anywhere under myTag.

I would like to use this xsd to create classes using jaxb for reading the value.

Any help is appreciated.

Thanks in advance. :)

Answer 1

If you can validate with XSD 1.1, you can use:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"
    xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning" vc:minVersion="1.1">
    <xs:complexType name="myTagType">
        <xs:sequence>
            <xs:any minOccurs="0" maxOccurs="unbounded" processContents="lax"/>
            <xs:element name="requiredTag" type="xs:string"/>
            <xs:any minOccurs="0" maxOccurs="unbounded" processContents="lax"/>
        </xs:sequence>
    </xs:complexType>
 ...
</xs:schema>

Unfortunately this fails in XSD 1.0 because it violates the Unique Particle Atribution constraint.

One workaround consists in using different namespaces for the any elements and requiredTag. Declare a schema with a namespace for the required tag:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 
           elementFormDefault="qualified" 
           xmlns="required-tag-ns" 
           targetNamespace="required-tag-ns">
    <xs:element name="requiredTag" type="xs:string"/>
</xs:schema>

Now import that into your schema (you will need a prefix for one of them):

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 
           elementFormDefault="qualified" 
           targetNamespace="any-tag-ns" 
           xmlns="any-tag-ns" 
           xmlns:r="required-tag-ns">

    <xs:import namespace="required-tag-ns" schemaLocation="required.xsd"/>

    <xs:complexType name="myTagType">
        <xs:sequence>
            <xs:any namespace="any-tag-ns" minOccurs="0" maxOccurs="unbounded" processContents="lax"/>
            <xs:element ref="r:requiredTag"/> <!-- now it works in 1.0 because the ambiguity was removed -->
            <xs:any namespace="any-tag-ns" minOccurs="0" maxOccurs="unbounded" processContents="lax"/>
        </xs:sequence>
    </xs:complexType>
   ...
</xs:schema>

Either the XSD 1.1 schema, or the XSD 1.0 schema above will validate these cases:

<myTag>
    <requiredTag>..</requiredTag>
</myTag>
<myTag>
    <someTag>..</someTag>
    <requiredTag>..</requiredTag>
</myTag>
<myTag>
    <requiredTag>..</requiredTag>
    <someotherTag>..</someotherTag>
</myTag>
<myTag>
    <someTag>..</someTag>
    <someotherTag>..</someotherTag>
    <someotherTag>..</someotherTag>
    <requiredTag>..</requiredTag>
    <someotherTag>..</someotherTag>
</myTag>
<myTag>
    <someTag>..</someTag>
    <requiredTag>..</requiredTag>
    <someTag>..</someTag>
    <someTag>..</someTag>
    <someotherTag>..</someotherTag>
</myTag>

But they will not validate these cases:

<myTag> <!-- missing requiredTag -->
    <someTag>..</someTag>
    <someotherTag>..</someotherTag>
</myTag>
<myTag> <!-- too many requiredTags -->
    <requiredTag>..</requiredTag>
    <requiredTag>..</requiredTag>
    <someotherTag>..</someotherTag>
</myTag>

In the XSD 1.1 version you won't need the namespaces. In the XSD 1.0 solution your instance will have to qualify the requiredTag with its namespace:

<myXml xmlns="any-tag-ns"
       xmlns:r="required-tag-ns"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="any-tag-ns your-schema-file.xsd">

    <myTag>
        <someTag>..</someTag>
        <someotherTag>..</someotherTag>
        <someotherTag>..</someotherTag>
        <r:requiredTag>..</r:requiredTag>
        <someotherTag>..</someotherTag>
    </myTag>
    ...
</myXml>