WCF Service throw custom exception to client

Question

I'm trying to throw a custom exception from a WCF Service to a Client application. I will try to describe as much code as I can think can be related to this.

Exception:

using System.Runtime.Serialization;

namespace App.Exceptions
{
    /// <summary>
    /// General App exception
    /// </summary>
    [DataContract]
    public class AppException : System.Exception
    {
        private string strMessage = "An unknown exception occurred";

        /// <summary>
        /// Creates a new instance of a App Exception
        /// </summary>
        public AppException()
        { }

        /// <summary>
        /// Creates a new instance of a App Exception
        /// </summary>
        /// <param name="Message">Message to send as exception</param>
        public AppException(string Message)
        { strMessage = Message; }

        public override string Message
        { get { return strMessage; } }
    }
}

Service code:

(...)
using App.Exceptions;

namespace App.Services
{
    public class Service1 : IService1
    {
        public Service1 () 
        { }

        public void TestFunction() 
        {
            throw new AppException();
        }
    }
}

ServiceInterface:

(...)

namespace App.Services.Interfaces
{
    [ServiceContract]
    public interface IService1
    {   
        [OperationContract]
        void TestFunction();
    }
}

Client:

(...)
using App.Exceptions;
(...)

try 
{
    service.TestFunction();
}
catch (AppException ex) 
{

}

Everything works very well, function is called on the service and exception is thrown. References are exactly the same either on Client and Server. I've cheched and AppException is being referenced on the same namepsace so it should be ok.

I've tried on service app.config to set <serviceDebug includeExceptionDetailInFaults="True" /> and also setting it to False just to see if I get a different Exception and in fact it is different so I'm not really understanding why the break point set on the catch for the AppException is never hit.

EDIT:

Service config:

  <service name="App.Services.Service1">
    <endpoint address="" binding="basicHttpBinding" contract="App.Services.Interfaces.IService1">
      <identity>
        <dns value="localhost" />
      </identity>
    </endpoint>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
    <host>
      <baseAddresses>
        <add baseAddress="http://localhost:8733/Design_Time_Addresses/App.Services/Service1/" />
      </baseAddresses>
    </host>
  </service>

Client config:

<system.serviceModel>
    <bindings>
        <basicHttpBinding>
            <binding name="BasicHttpBinding_IService1" />
        </basicHttpBinding>
    </bindings>
    <client>
        <endpoint address="http://localhost:8733/Design_Time_Addresses/App.Services/Service1/"
            binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IService1"
            contract="Services.IService1" name="BasicHttpBinding_IService1" />
    </client>
</system.serviceModel>

Answer 1

You cannot throw any unhandled exceptions or .net or any exceptions like that from the server to the client(if client want to know the excpetions) because of security and interoperability reasons ,these exceptions by default are not propagated to clients from the wcf service.

Instead of propagating the exceptions,the WCF serializes them into SOAP fault and sends SOAP fault to the client.So you need to include this custom exception in SOAP fault.

First Let the servicecontract know the which operation can throw which SOAP faults.

namespace App.Services.Interfaces
{
    [ServiceContract]
    public interface IService1
    {   
        [FaultContract(typeOf(AppException))]
        [OperationContract]
        void TestFunction();
    }
}


using System.ServiceModel;
public class Service1 : IService1
    {
        public Service1 () 
        { }

        public void TestFunction() 
        {
            try
            {
             service.TestFunction();
            }
            catch(Exception ex)
             {
               AppException app=new AppException();
               app.strMessage =ex.Message;
               throw new FaultExcpetion<AppException>(app);
             }
        }
    }

Additionally ,you can have fault details and well as fault error.Catch the above exception at the client side.

//client side

     try
                {
                  //call wcf service contract.
                }
                catch (FaultException<ServiceReference.AppException> ex)
                {

                   label.Text=ex.Detail.strMessage ;
                }

One more way is to use custom WCF IErrorHandler implementation.Refer this https://stackoverflow.com/a/8764782/6086968 for centralized way of handling exceptions.

Edit1:The app.config need to be configured properly for metadata.

    <service name="App.Services.Service1" behaviorConfiguration="mexendpoint">
        <endpoint address="" binding="basicHttpBinding" contract="App.Services.Interfaces.IService1">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8733/Design_Time_Addresses/App.Services/Service1/" />
          </baseAddresses>
        </host>
      </service>
<behaviors>
  <serviceBehaviors>  
    <behavior name="mexendpoint">
      <serviceMetadata httpGetEnabled="true"/>
      <serviceDebug includeExceptionDetailInFaults="true"/>
    </behavior>
     </serviceBehaviors>
</behaviors>
</system.serviceModel>