How to ignore the validation of Unknown tags?
In case your not already done with this, you might try the following:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="root" type="root"></xs:element> <xs:complexType name="root"> <xs:sequence> <xs:any maxOccurs="2" minOccurs="0" processContents="skip"/> <xs:element name="node" type="xs:string"/> <xs:any maxOccurs="2" minOccurs="0" processContents="skip"/> </xs:sequence> </xs:complexType></xs:schema>Under Linux this works fine with xmllint using libxml version 20706.
Conclusion:
This is not possible with XSD. All the approaches I was trying to achieve the requirement were named as "ambiguous" by validation-tools, accompanying bunch of errors.
You could make use of a new feature in XML 1.1 called "Open Content". In short, it allows you to specify that additional "unknown" elements can be added to a complex type in various positions, and what the parser should do if it hit any of those elements.
Using XML 1.1, your complex type would become:
<xs:element name="root" type="root" /><xs:complexType name="root"> <xs:openContent mode="interleave"> <xs:any namespace="##any" processContents="skip"/> </xs:openContent> <xs:sequence> <xs:element name="node" type="xs:string"/> </xs:sequence> </xs:complexType>If you have a lot of complex types, you can also set a "default" open content mode at the top of your schema:
<xs:schema ...> <xs:defaultOpenContent mode="interleave"> <xs:any namespace="##any" processContents="skip"/> </xs:defaultOpenContent> ...</xs:schema>The W3C spec for Open Content can be found at http://www.w3.org/TR/xmlschema11-1/#oc, and there's a good writeup of this at http://www.ibm.com/developerworks/library/x-xml11pt3/#N102BA.
Unfortunately, .NET doesn't support XML 1.1 as of yet I can't find any free XML 1.1 processors - but a couple of paid-for options are: