Possible to consume badly formed Fault Messages?

Question

I've a WCF client communicating with an unknown server implementation which I have no control over. This client works fine it just doesn't like, what appears to be, incorrectly formed SOAP Fault messages. The messages I receive look like:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">   
    <soap:Header>...</soap:Header>  
    <soap:Body>  
        <soap:Fault>  
            <soap:faultcode>soap:Client</soap:faultcode>  
            <soap:faultstring>...</soap:faultstring>  
            <soap:detail>...</soap:detail>  
        </soap:Fault>  
    </soap:Body>  
</soap:Envelope>  

I believe according to the soap schema the child elements shouldn't be qualified and ned to look like:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">   
    <soap:Header>...</soap:Header>  
    <soap:Body>  
        <soap:Fault>  
            <faultcode>soap:Client</faultcode>  
            <faultstring>...</faultstring>  
            <detail>...</detail>  
        </soap:Fault>  
    </soap:Body> 
</soap:Envelope>

Is there something that I can configure or override so that I can consume messages which arrive in the latter format so that I can consume the fault messages instead of xml exceptions?

Answer 1

I'm cannot recall how I found stumbled across Message Inspectors, but that it how I solved my problem.

This and this article provided the base for creating the inspector, and what follows is the meat of the inspector:

public void AfterReceiveReply(ref Message reply, object correlationState)
{
    if (!reply.IsFault)
        return;

    var document = new XmlDocument();

    document.Load(reply.GetReaderAtBodyContents());

    var navigator = document.CreateNavigator();
    var manager = new XmlNamespaceManager(navigator.NameTable);

    manager.AddNamespace("soap", "http://schemas.xmlsoap.org/soap/envelope/");

    var it = navigator.Select("//soap:Fault", manager);

    if (it.MoveNext() && it.Current.HasChildren && it.Current.MoveToChild(XPathNodeType.Element))
    {
        do
        {
            var c = it.Current;

            if (string.IsNullOrEmpty(c.Prefix))
                continue;

            c.ReplaceSelf("<" + c.LocalName + ">" + c.InnerXml + "</" + c.LocalName + ">");

            /// we may want to record the detail included inside the detail element, 
            /// it is not reported in the FaultException that is raised.

        } while (it.Current.MoveToNext());
    }

    var reader = XmlDictionaryReader.CreateDictionaryReader(new XmlNodeReader(document));

    reader.MoveToStartElement();

    var fixedReply = Message.CreateMessage(reply.Version, null, reader);

    fixedReply.Headers.CopyHeadersFrom(reply.Headers);
    fixedReply.Properties.CopyProperties(reply.Properties);

    reply = fixedReply;
}

Answer 2

It looks like the offending application is using a custom (and badly implemented) SOAP library. The following article might help (I haven't had to deal with this as of yet as I am in a pure .Net shop).

http://msdn.microsoft.com/en-us/library/ms733721.aspx

Answer 3

Note that the System.Web.Services.Protocols.SoapHttpClientProtocol class seems significantly more tolerant of malformed Fault responses than WCF.

This is sometimes referred to as ASMX services protocol. That may be an option to consider as well.

Howard Hoffman

Answer 4

} catch (SoapFaultClientException e) {
    log.error(e);
    SoapFaultDetail soapFaultDetail = e.getSoapFault().getFaultDetail();
    SoapFaultDetailElement detailElementChild = (SoapFaultDetailElement) soapFaultDetail.getDetailEntries().next();
    Source detailSource = detailElementChild.getSource();

    try {
        Object detail = (JAXBElement<SearchResponse>) getWebServiceTemplate().getUnmarshaller().unmarshal(detailSource);
//                throw new SoapFaultWithDetailException(detail);

    } catch (IOException e1) {
        throw new IllegalArgumentException("cannot unmarshal SOAP fault detail object: " + soapFaultDetail.getSource());
    }

}