Extending WCF Service Calls from the Client-Side

I am using my WCF service to communicate with an external web-service which I do not control. Now, I would like to add a behavior to the operations being called such that, whenever it is impossible to communicate with the service, something should be logged to the database via a specifical stored procedure (no NLog/Log4Net in this case, it is really a stored procedure). However, I do not want to write code for this in each method calling the service, so I think a behavior should be more appropriate. How can I go about accomplis开发者_JS百科hing this?

You can use an IClientMessageInspector in your client, which, whenever it receives a call after receiving the reply, it would check whether the response is successful or not (i.e., a fault). If it isn't, you can log it appropriately. The code below shows an example of a client message inspector doing this. And you can find out more about message inspectors at http://blogs.msdn.com/b/carlosfigueira/archive/2011/04/19/wcf-extensibility-message-inspectors.aspx.

public class StackOverflow_7484237
{
    [ServiceContract]
    public interface ITest
    {
        [OperationContract]
        string Echo(string text);
    }
    public class Service : ITest
    {
        public string Echo(string text)
        {
            if (text == "throw")
            {
                throw new ArgumentException("This will cause a fault to be received at the client");
            }
            else
            {
                return text;
            }
        }
    }
    public class MyInspector : IEndpointBehavior, IClientMessageInspector
    {
        public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
        {
            clientRuntime.MessageInspectors.Add(this);
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
        {
        }

        public void Validate(ServiceEndpoint endpoint)
        {
        }

        public void AfterReceiveReply(ref Message reply, object correlationState)
        {
            if (reply.IsFault)
            {
                Console.WriteLine("Log this fault: {0}", reply);
            }
        }

        public object BeforeSendRequest(ref Message request, IClientChannel channel)
        {
            return null;
        }
    }
    public static void Test()
    {
        string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
        host.AddServiceEndpoint(typeof(ITest), new BasicHttpBinding(), "");
        host.Open();
        Console.WriteLine("Host opened");

        var factory = new ChannelFactory<ITest>(new BasicHttpBinding(), new EndpointAddress(baseAddress));
        factory.Endpoint.Behaviors.Add(new MyInspector());
        var proxy = factory.CreateChannel();

        Console.WriteLine(proxy.Echo("This won't throw"));

        try
        {
            Console.WriteLine(proxy.Echo("throw"));
        }
        catch (Exception e)
        {
            Console.WriteLine("Exception: {0}", e);
        }

        ((IClientChannel)proxy).Close();
        factory.Close();

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }
}