WCF HTTP/SOAP Webservice – Returning exception message in faults

custom-errorssoapexceptionwcf

I have asimple WCF HTTP/SOAP web service, the service implementation looks something like this:

public CustomResponse DoSomething(CustomRequest request)
{
    try
    {
        return InternalGubbins.WithErrorHandling.ProcessRequest(request);
    }
    catch
    {
        // Some sort of error occurred that is not gracefully
        // handled elsewhere in the framework
        throw new SoapException("Hmmm, it would seem that the cogs are meshed!", SoapException.ServerFaultCode);
    }
}

Now, if that SoapException is thrown I would like the exception message (i.e. Hmmm, it would seem that the cogs are meshed!) to be returned to the invoking client without any additional exception detail (i.e. stack traces).

If I set includeExceptionDetailInFaults to true (web.config on the server) then the full exception, with stack traces etc, is return to the client. However if I set it to false, I get a generic message:

The server was unable to process the
request due to an internal error. For
more information about the error,
either turn on
IncludeExceptionDetailInFaults (either
from ServiceBehaviorAttribute or from
the configuration
behavior) on the server in order to
send the exception information back to
the client, or turn on tracing as per
the Microsoft .NET Framework 3.0 SDK
documentation and inspect the server
trace logs.

So the question is, how can I get my SoapException message back to the invoking client? i.e:

<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://www.w3.org/2005/08/addressing">
    <s:Header>
        <a:Action s:mustUnderstand="1">http://schemas.microsoft.com/net/2005/12/windowscommunicationfoundation/dispatcher/fault</a:Action>
        <a:RelatesTo>urn:uuid:185719f4-6113-4126-b956-7290be375342</a:RelatesTo>
    </s:Header>
    <s:Body>
        <s:Fault>
            <s:Code>
                <s:Value>s:Receiver</s:Value>
                <s:Subcode>
                    <s:Value xmlns:a="http://schemas.microsoft.com/net/2005/12/windowscommunicationfoundation/dispatcher">a:InternalServiceFault</s:Value>
                </s:Subcode>
            </s:Code>
            <s:Reason>
                <s:Text xml:lang="en-GB">Hmmm, it would seem that the cogs are meshed!</s:Text>
            </s:Reason>
        </s:Fault>
    </s:Body>
</s:Envelope>

Best Answer

I think you need to declare a FaultContract on the operation and use FaultException (SoapException is pre WCF). I believe WCF does not send faults back to the client if they are not part of the service contract. I have never tried SoapException but certainly throwing a FaultException has always worked fine for me.

[ServiceContract()]    
public interface ISomeService
{
     [OperationContract]
     [FaultContract(typeof(MyFault))]
     CustomResponse DoSomething(CustomRequest request)
}

public class SomeService
{
    public CustomResponse DoSomething(CustomRequest request)
    {
        ...
        throw new FaultException<MyFault>(new MyFault());
    }
}

Reply to the post for SOAP and RESTful POX(XML)

For plain old XML as return format, this is an example that would work both for SOAP and XML.

[ServiceContract(Namespace = "http://test")]
public interface ITestService
{
    [OperationContract]
    [WebGet(UriTemplate = "accounts/{id}")]
    Account[] GetAccount(string id);
}

POX behavior for REST Plain Old XML

<behavior name="poxBehavior">
  <webHttp/>
</behavior>

Endpoints

<services>
  <service name="TestService">
    <endpoint address="soap" binding="basicHttpBinding" contract="ITestService"/>
    <endpoint address="xml" binding="webHttpBinding"  behaviorConfiguration="poxBehavior" contract="ITestService"/>
  </service>
</services>

Service will be available at

REST request try it in browser,

http://www.example.com/xml/accounts/A123

SOAP request client endpoint configuration for SOAP service after adding the service reference,

  <client>
    <endpoint address="http://www.example.com/soap" binding="basicHttpBinding"
      contract="ITestService" name="BasicHttpBinding_ITestService" />
  </client>

in C#

TestServiceClient client = new TestServiceClient();
client.GetAccount("A123");

Another way of doing it is to expose two different service contract and each one with specific configuration. This may generate some duplicates at code level, however at the end of the day, you want to make it working.

.net – WCF – How toncrease Message Size Quota

You'll want something like this to increase the message size quotas, in the App.config or Web.config file:

<bindings>
    <basicHttpBinding>
        <binding name="basicHttp" allowCookies="true"
                 maxReceivedMessageSize="20000000" 
                 maxBufferSize="20000000"
                 maxBufferPoolSize="20000000">
            <readerQuotas maxDepth="32" 
                 maxArrayLength="200000000"
                 maxStringContentLength="200000000"/>
        </binding>
    </basicHttpBinding>
</bindings>

And use the binding name in your endpoint configuration e.g.

...
bindingConfiguration="basicHttp"
...

The justification for the values is simple, they are sufficiently large to accommodate most messages. You can tune that number to fit your needs. The low default value is basically there to prevent DOS type attacks. Making it 20000000 would allow for a distributed DOS attack to be effective, the default size of 64k would require a very large number of clients to overpower most servers these days.

Best Answer

Related Solutions

REST / SOAP endpoints for a WCF service

Reply to the post for SOAP and RESTful POX(XML)

.net – WCF – How toncrease Message Size Quota

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