XML Schema: complexContent/extension

[res1st]

Hi!
i want to define a base type (CasDataType) and then "subclass" it.
I found the XML Schema element complexContent+extension which seems to fit for my needs.
Please look at my XML Schema snippet.

<complexType name="CasDataType">
  <sequence>
    <element name="key"  type="long"  nillable="false  minOccurs="1" maxOccurs="1"/>
  </sequence>
</complexType>

<complexType name="AddressDataType">
  <complexContent>
    <extension base="tns:CasDataType">
      <sequence>
        <element name="FirstName"  nillable="true" minOccurs="0" type="string"/>
        <element name="LastName"  nillable="true" minOccurs="0" type="string"/>
      </sequence>
    </extension>
  </complexContent>
</complexType>
	
<complexType name="ArrayOfCasDataTypes">
  <sequence>
    <element name="casDataTypes"  type="tns:CasDataType"	nillable="false" minOccurs="1" maxOccurs="unbounded"/>
  </sequence>
</complexType>
	
<element name="createDataTypesRequest"  type="tns:ArrayOfCasDataTypes"/>
	
<element name="createDataTypesResponse" type="tns:ArrayOfCasDataTypes"/>

I'm creating AddressDataType objects in my endpoint method invokeInternal(...) and want to returm this objects. But i get an validation error ant my soap message looks like this:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  <SOAP-ENV:Header /> 
  <SOAP-ENV:Body>
  <createDataTypesResponse xmlns="http://springws.cas.de">
    <casDataTypes>
      <key>123</key> 
      <FirstName>Ingo</FirstName> 
      <LastName>Siebert</LastName> 
    </casDataTypes>
    <casDataTypes>
      <key>456</key> 
      <FirstName>Ingo</FirstName> 
      <LastName>Siebert</LastName> 
    </casDataTypes>
  </createDataTypesResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

As we can see, i get casDataTypes and not AddressDataType. Why? I thought that "casDataTypes" is only the name of the array. Instead this is the element name of array elements.
Has anyone an idea, how i can provide one method for several "subclassed" (with complexContent/extension) XML schema elements?

Cheers,

Ingo

[Arjen Poutsma]

But i get an validation error ant my soap message looks like this:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  <SOAP-ENV:Header /> 
  <SOAP-ENV:Body>
  <createDataTypesResponse xmlns="http://springws.cas.de">
    <casDataTypes>
      <key>123</key> 
      <FirstName>Ingo</FirstName> 
      <LastName>Siebert</LastName> 
    </casDataTypes>
    <casDataTypes>
      <key>456</key> 
      <FirstName>Ingo</FirstName> 
      <LastName>Siebert</LastName> 
    </casDataTypes>
  </createDataTypesResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

As we can see, i get casDataTypes and not AddressDataType. Why?

You get a validation error because the XML is not valid according to your schema . Don't you just love that PayloadValidatingInterceptor?

What I would expect to see in the payload is this:

<createDataTypesResponse xmlns="http://springws.cas.de" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <casDataTypes xsi:type="AddressDataType" >
      <key>123</key> 
      <FirstName>Ingo</FirstName> 
      <LastName>Siebert</LastName> 
    </casDataTypes>
  </createDataTypesResponse>

Note the xsi:type attribute. That tells the XML parser that the type is actually an address data type. If this attribute is added, the XML is valid.

I thought that "casDataTypes" is only the name of the array. Instead this is the element name of array elements.

Try and look at this from an XML perspective, and let's forget about Java for a while. In ArrayOfCasDataTypes, you are defining a sequence (=list) of elements. Each element is called casDataType. It's that simple.

Has anyone an idea, how i can provide one method for several "subclassed" (with complexContent/extension) XML schema elements?

The trick seems to be to add the xsi:type attribute I mentioned above, which is more a JAXB thing than anything else. This thread seems to be related to your problem, and you might also want to check out the type-substitution sample that comes with JWDSP 2.0's JAXB implementation.

Cheers,

[fgt]

The trick seems to be to add the xsi:type attribute I mentioned above, which is more a JAXB thing than anything else.

So this means this is not interoperable with other clients than JAXB clients?

Perhaps the xsi:type approach works with .NET or other Java Bindings, I have not tried yet..., but can we use this in the future?

Currennlty I think there is no other way than to wrap the whole thing:
e.g.

<complexType name="CasDataTypeWrapper">
   <choice>
	<element name="AddressDataType" type="tns:AddressDataType" />
	<element name="OtherExtendedCasDataType" type="tns:OtherExtendedCasDataType" />
   </choice>
</complexType>

<complexType name="ArrayOfCasDataTypes">
  <sequence>
    <element name="casDataTypes"  type="tns:CasDataTypeWrapper"	nillable="false" minOccurs="1" maxOccurs="unbounded"/>
  </sequence>
</complexType>

and then take the right out..., well seems not to look nice.

Knows somebody another approach to be interoperable with Java and .NET or whatever clients. Have nothing found in the WS-I. What are your solutions to this?

Cheers,
Patrick

[Arjen Poutsma]

So this means this is not interoperable with other clients than JAXB clients?

Perhaps the xsi:type approach works with .NET or other Java Bindings, I have not tried yet..., but can we use this in the future?

The xsi:type is a completely valid XSD construct which is exactly designed for cases like these. It just explicitly sets the schema type for an element. In fact, .NET uses it in this situation too!

What I meant with "more a JAXB thing than anything else" is that JAXB should be instructed to add this attribute. I'm not a complete JAXB expert, so I don't know how this can be accomplished, but a simple google search resulted in the resources I gave above. They seem related.

Best,

[res1st]

Don't you just love that PayloadValidatingInterceptor?

Of course, it's really cute.

Note the xsi:type attribute. That tells the XML parser that the type is actually an address data type.

That sounds logical. Now i know my goal, only the way is unknown. If can't do it with jaxb, i'll try another one. It's just a bean exchange with SpringWS....i hope.

The trick seems to be to add the xsi:type attribute I mentioned above, which is more a JAXB thing than anything else.

I've posted my problem to java.net. If i get a good answer, i'll post it here.

<complexType name="CasDataTypeWrapper">
<choice>
<element name="AddressDataType" type="tns:AddressDataType" />
<element name="OtherExtendedCasDataType" type="tns:OtherExtendedCasDataType" />
</choice>
</complexType>

Thank you Patrick! I tried it and i have now an AddressDataType element. The "type=AddressDataType" thing seems to be more correct, but your solution is much better than nothing. Thank you.

Cheers,

Ingo

[res1st]

<createDataTypesResponse xmlns="http://springws.cas.de" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <casDataTypes xsi:type="AddressDataType" >
      <key>123</key> 
      <FirstName>Fritz</FirstName> 
      <LastName>Meier</LastName> 
    </casDataTypes>
  </createDataTypesResponse>

JAXB 1.6 doesn't handle that it right, it never produces the xsi:type attribute which i need.
I switched back to JAXB 2.0 and it's working nearly fine. I got the following soap response:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  <SOAP-ENV:Header /> 
  <SOAP-ENV:Body>
    <ns2:createDataTypesResponse xmlns:ns2="http://springws.cas.de">
      <ns2:casDataType 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
          xsi:type="ns2:AddressDataType">
        <ns2:key>123</ns2:key> 
        <ns2:firstName>Fritz</ns2:firstName> 
        <ns2:lastName>Meier</ns2:lastName> 
      </ns2:casDataType>
    </ns2:createDataTypesResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

The Problem is, that i get an validation error in my log file. Any idea why?

DEBUG webservice.CreateDataTypesRequestEndpoint  - Unmarshalled payload request to [javax.xml.bind.JAXBElement@13ed2e3]
DEBUG webservice.CreateDataTypesRequestEndpoint  - Marshalling [javax.xml.bind.JAXBElement@1873ad9] to response payload
ERROR endpoint.PayloadValidatingInterceptor  - XML validation error on response: UndeclaredPrefix: Cannot resolve 'ns2:AddressDataType' as a QName: the prefix 'ns2' is not declared.
ERROR endpoint.PayloadValidatingInterceptor  - XML validation error on response: cvc-elt.4.1: The value 'ns2:AddressDataType' of attribute 'http://www.w3.org/2001/XMLSchema-instance,type' of element 'ns2:casDataType' is not a valid QName.
ERROR endpoint.PayloadValidatingInterceptor  - XML validation error on response: UndeclaredPrefix: Cannot resolve 'ns2:AddressDataType' as a QName: the prefix 'ns2' is not declared.
ERROR endpoint.PayloadValidatingInterceptor  - XML validation error on response: cvc-attribute.3: The value 'ns2:AddressDataType' of attribute 'xsi:type' on element 'ns2:casDataType' is not valid with respect to its type, 'QName'.
ERROR endpoint.PayloadValidatingInterceptor  - XML validation error on response: cvc-complex-type.2.4.d: Invalid content was found starting with element 'ns2:firstName'. No child element is expected at this point.

Cheers,

Ingo