Can't import XML schema with ref to external namespace

Question

In TopLink 10.1.3 Dev Preview 3 (build 041116), I have 2 simple schema files. One defines an element as a ref to an element in the other schema, so the ref points to an element in an external namespace. TopLink won't import this schema.
First schema, imports fine:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
   xmlns:xs="http://www.w3.org/2001/XMLSchema"
   targetNamespace="http://www.oracle.com/employee"
   xmlns="http://www.oracle.com/employee"
   elementFormDefault="qualified"
   attributeFormDefault="unqualified">
     <xs:element name="employee">
       <xs:complexType>
         <xs:sequence>
                <xs:element name="name" type="xs:string"/>
         </xs:sequence>
       </xs:complexType>
     </xs:element>
</xs:schema>
Second schema, fails import with "ERROR: null. Please check to ensure the document conforms to the XML Schema specification and try again":
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
   xmlns:xs="http://www.w3.org/2001/XMLSchema"
   targetNamespace="http://www.oracle.com/department"
   xmlns="http://www.oracle.com/department"
   xmlns:employee="http://www.oracle.com/employee"
   elementFormDefault="qualified"
   attributeFormDefault="unqualified">
   <xs:import
     namespace="http://www.oracle.com/employee"
         schemaLocation="employee.xsd"/>
   <xs:element name="department">
     <xs:complexType>
       <xs:sequence>
         <xs:element ref="employee:employee"         maxOccurs="unbounded"/>
       </xs:sequence>
     </xs:complexType>
   </xs:element>
</xs:schema>
Both schemas are valid according to the W3C schema validation checker at http://www.w3.org/2001/03/webdata/xsv.
I can work around the issue by putting the employee definitions into the department schema file so that all elements are in the same namespace. But I would like the schemas to be in separate files for better modularity and maintainability.
Am I doing something wrong? I would really like to be able to use references to external namespaces in my element definitions.
Thanks,
Dave

Answer 1

Hello David,
Apologies, but this is a bug in DP3 with respect to references to elements in imported namespaces. This has been fixed in current code, but until you get that, there are a couple ways to work around it:
==========================================================
1) Use an include rather than an import.
department.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
    targetNamespace="http://www.oracle.com/department"
    xmlns="http://www.oracle.com/department"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
   <xs:include schemaLocation="employee.xsd"/>
   <xs:element name="department">
      <xs:complexType>
         <xs:sequence>
            <xs:element ref="employee" maxOccurs="unbounded"/>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
</xs:schema>employee.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    targetNamespace="http://www.oracle.com/department"
    xmlns="http://www.oracle.com/department"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
   <xs:element name="employee">
      <xs:complexType>
         <xs:sequence>
            <xs:element name="name" type="xs:string"/>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
</xs:schema>You should only have to import the parent schema (i.e. department.xsd), as the included document will automatically be built in. Note that this works for imports as well, provided that there aren't nasty bugs blocking the process.
==========================================================
2. Build everything into the same document
department.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
    targetNamespace="http://www.oracle.com/department"
    xmlns="http://www.oracle.com/department"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
   <xs:element name="department">
      <xs:complexType>
         <xs:sequence>
            <xs:element ref="employee" maxOccurs="unbounded"/>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
   <xs:element name="employee">
      <xs:complexType>
         <xs:sequence>
            <xs:element name="name" type="xs:string"/>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
</xs:schema>Obviously, this one won't work quite as well in some cases.
==========================================================
Until you can get to the latest code, I hope this helps some.
- Paul