Service Response to WCF Includes Duplicate Namespace and Tag Prefix

Question

Question:

Why would I receive a SOAP response fragment that contains a duplicate tag prefix namespace?
Why would I receive a different response fragment in SoapUI versus a WCF client using the exact same SOAP request?

Context:
I am calling a third-party, Java based web service with a WCF client. The SOAP fragment response sent from the third party WS contains a duplicate namespace and tag prefix for the soap envelope on the Fault tag line when calling with an incorrect value that results in a fault response. This causes the WCF to throw a CommunicationException with an innerException of XmlException which cites the following as the error:

Start element 'faultcode' from namespace '' expected. Found element 'SOAP-ENV:faultcode' from namespace 'http://schemas.xmlsoap.org/soap/envelope/'.

This error message leads me to believe the duplicated namespace in the SOAP fragment is the culprit. The weird thing is, using the exact SOAP request sent from the WCF client to the web service in SoapUI does not result in this namespace being duplicated in the SOAP response fragment.

The WCF client is using a basicHttpBinding.

Please see below for SOAP fragments of the request, response through WCF, and response through SoapUI.

Request sent by both WCF and SoapUI:

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
    <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
        <Search xmlns="urn:ent.soap.testservice.com/objs">
            <Request objType="Report">
                <RequestorId>ABCD</RequestorId>
                <TargetId></TargetId>
            </Request>
        </Search>
    </s:Body>
</s:Envelope>

Response received by WCF client:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
    <SOAP-ENV:Header/>
    <SOAP-ENV:Body>
        <SOAP-ENV:Fault xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
            <SOAP-ENV:faultcode>SOAP-ENV:Server</SOAP-ENV:faultcode>
            <SOAP-ENV:faultstring>Invalid action parameters</SOAP-ENV:faultstring>
            <SOAP-ENV:detail>
                <fns:fault xmlns:fns="urn:fault.soap.testservice.com" xmlns:java="java" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="fns:ApiFault">
                    <fns:exceptionCode>INTERNAL_ERROR</fns:exceptionCode>
                    <fns:exceptionMessage>Invalid action parameters</fns:exceptionMessage>
                    <fns:logDataExchangeId>1234567890</fns:logDataExchangeId>
                </fns:fault>
            </SOAP-ENV:detail>
        </SOAP-ENV:Fault>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Response received by SoapUI:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
    <SOAP-ENV:Header/>
    <SOAP-ENV:Body>
        <SOAP-ENV:Fault>
            <SOAP-ENV:faultcode>SOAP-ENV:Server</SOAP-ENV:faultcode>
            <SOAP-ENV:faultstring>Invalid action parameters</SOAP-ENV:faultstring>
            <SOAP-ENV:detail>
                <fns:fault xsi:type="fns:ApiFault" xmlns:fns="urn:fault.soap.testservice.com" xmlns:java="java" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                    <fns:exceptionCode>INTERNAL_ERROR</fns:exceptionCode>
                    <fns:exceptionMessage>Invalid action parameters</fns:exceptionMessage>
                    <fns:logDataExchangeId>1234567890</fns:logDataExchangeId>
                </fns:fault>
            </SOAP-ENV:detail>
        </SOAP-ENV:Fault>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

1) What does the WSDL say the response should be? 2) The two sample responses you posted are XML-identical, even though they are not byte-identical; it's just how the client displays it to you. — SiKing

tomasr tomasr · Accepted Answer · 2014-12-19T22:16:14

The problem is not the duplicated namespace declaration. The problem is in this bit:

    <SOAP-ENV:faultcode>SOAP-ENV:Server</SOAP-ENV:faultcode>
    <SOAP-ENV:faultstring>Invalid action parameters</SOAP-ENV:faultstring>

On the SOAP Specification, the faultcode and faultstring elements are in the empty, default namespace, not in the "http://schemas.xmlsoap.org/soap/envelope/" namespace. So it really should've looked something like this:

 <SOAP-ENV:Fault>
       <faultcode>SOAP-ENV:MustUnderstand</faultcode>
       <faultstring>SOAP Must Understand Error</faultstring>
   </SOAP-ENV:Fault>

So looks like this service in particular is not being compliant with the SOAP 1.1 (or 1.2 for that matter) specification.

Service Response to WCF Includes Duplicate Namespace and Tag Prefix

1 Answers