sca:endpointReference versus wsa:EndpointReference for WS Binding

Is there a particular reason why the ws
binding schema defines it's own endpointReference element based on wsa:EndpointReferenceType
without extending it, instead of just referencing the wsa:EndpointReference
directly ? 

Here is the snipet from the ws binding
xsd :

<complexType name="WebServiceBinding">
        <complexContent>
           
<extension base="sca:Binding">
           
    <sequence>
           
        <element name="endpointReference"
type="wsa:EndpointReferenceType"
           
                 minOccurs="0"
maxOccurs="unbounded"/>
           
        <any namespace="##other" processContents="lax"
           
             minOccurs="0"
maxOccurs="unbounded"/>
           
    </sequence>
           
    <attribute name="wsdlElement" type="anyURI"
use="optional"/>
           
    <attribute ref="wsdli:wsdlLocation" use="optional"/>
           
</extension>
        </complexContent>
    </complexType>

This requires composites to have the
following when configuring the ws binding. Note that although endpointReference
is an element defined from sca namespace, we still need to use the child
elements based on the wsa namespace.

         
      <binding.ws wsdlElement="http://helloworld#wsdl.binding(HelloWorldSoapBinding)">
         
         <endpointReference>
         
            <wsa:Address xmlns:wsa="http://www.w3.org/2005/08/addressing">http://localhost:8085/services/HelloWorldWebService1</wsa:Address>
         
         <endpointReference>
         
      </binding.ws>

[1] http://tools.oasis-open.org/version-control/svn/sca-assembly/SCA_XSDS/sca-binding-ws-1.1-cd04.xsd
[2] http://www.w3.org/2006/03/addressing/ws-addr.xsd

- Luciano 

Luciano Resende
Open Source SOA - Apache
Tuscany
4400 N 1st St, San Jose - CA 
notes: Luciano
Resende/Westford/IBM
internet IBM: 
internet ASF:  blog @ developerWorks : link
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