System.Xml.XmlSchemaSet compile() fills included schema TargetNamespace

Question

I have two xml schemas:
1) infrastructureRoot.xsd:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:mif="urn:hl7-org:v3/mif" 
  xmlns:v3="urn:hl7-org:v3" 
  xmlns:ex="urn:hl7-org/v3-example" 
  xmlns="urn:hl7-org:v3" 
  targetNamespace="urn:hl7-org:v3" 
  elementFormDefault="unqualified">
  <xs:include schemaLocation="datatypes-base.xsd"/>
  <xs:group name="InfrastructureRootElements">
    <xs:sequence>
      <xs:element name="realmCode" 
                  type="Norwegian_customer" 
                  minOccurs="0" 
                  maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:group>
  <xs:attributeGroup name="InfrastructureRootAttributes"/>
</xs:schema>

2)datatypes-base.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:sch="http://www.ascc.net/xml/schematron"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"  
  elementFormDefault="unqualified">
  <xs:complexType name="customer">
    <xs:sequence>
      <xs:element name="firstname" type="xs:string"/>
      <xs:element name="lastname" type="xs:string"/>
      <xs:element name="country" type="xs:string"/>
    </xs:sequence>
  </xs:complexType>
  <xs:complexType name="Norwegian_customer">
    <xs:complexContent>
     <xs:restriction base="customer">
       <xs:sequence>
         <xs:element name="firstname" type="xs:string"/>
         <xs:element name="lastname" type="xs:string"/>
         <xs:element name="country" 
           type="xs:string" 
           fixed="Norway"/>
     </xs:sequence>
   </xs:restriction>
  </xs:complexContent>
 </xs:complexType>
</xs:schema>

I use following C# code for load the root schema with all includes:

Func<XmlReader> xmlReaderFactory = () =>
                                        {
                                            XmlReaderSettings schemaReaderSettings = new XmlReaderSettings{ DtdProcessing = DtdProcessing.Parse};
                                                XmlTextReader reader = new XmlTextReader(@"InfrastructureRoot.xsd");
                                            return XmlReader.Create(reader, schemaReaderSettings);
                                        };

XmlSchema xsd = XmlSchema.Read(xmlReaderFactory(), (sender, eventArgs) => {});
XmlSchemaSet schemaSet = new XmlSchemaSet();
schemaSet.ValidationEventHandler += (sender, eventArgs) => Console.WriteLine(eventArgs.Message + " " + eventArgs.Severity);

try
{
    try
    {
        XmlReaderSettings schemaReaderSettings = new XmlReaderSettings {DtdProcessing = DtdProcessing.Parse};
        XmlReader schemaReader = XmlReader.Create(new DummyReader(), schemaReaderSettings);
        schemaSet.Add(null, schemaReader);
    }
    catch
    {
        // the only thing this code is needed is to set ProhibitDTD to false
        // there is no acceptable public way to do that
    }

    schemaSet.Add(xsd);
    schemaSet.Compile();
    XmlSchemaInclude external = ((XmlSchemaInclude)xsd.Includes[0]);
    String targetNamespace = external.Schema.TargetNamespace;
    Debug.Assert(targetNamespace == null);
}
catch{}

After execution "targetNamespace" value equals "urn:hl7-org:v3" , which is differ from the original schema "datatypes-base.xsd" and breaks validation. Can someone help me with solution?

Answer 1

We've been working with HL7v3 and CDA in BizTalk and .Net. To get the CDA schemas to work correctly for validation and just sending messages, I had to add a targetnamespace of urn:hl7-org:v3 to all the "coreschemas" xsd files. After that validation worked and BizTalk messages flowed.

I didn't feel comfortable adding the targetnamespaces to schemas that I don't really own, but it was a decent compromise, since I never actually altered the schemas themselves and things worked afterwards.