Question

My application calls a web-service using WCF. The call can fail for various reasons:

• fault
• timeout
• connection lost
• …

I want to log all such errors. Instead of wrapping every call in a try-catch, I want to do this in one place for all web-service calls in the entire application.

Unfortunately, an IClientMessageInspector does not get called for timeouts and connection failures. Is there a WCF extensibility point that I can use to centrally take note of all exceptions?

Notice, that I do not just want to log errors as text like WCF Tracing does it. I want to log:

• ServiceName
• MethodName
• Duration
• Exception.ToString()

I am open to workarounds.

Answer 1

I am not aware of an extensibility point, but I can provide a workaround that we have used. Basically, we created a “proxy” that all service calls were made through. Below is the proxy and an example of its use.

/// <summary>
/// Proxy for executing generic service methods
/// </summary>
public class ServiceProxy
{
    /// <summary>
    /// Execute service method and get return value
    /// </summary>
    /// <typeparam name="C">Type of service</typeparam>
    /// <typeparam name="T">Type of return value</typeparam>
    /// <param name="action">Delegate for implementing the service method</param>
    /// <returns>Object of type T</returns>
    public static T Execute<C, T>(Func<C, T> action) where C : class, ICommunicationObject, new()
    {
        C svc = null;

        T result = default(T);

        try
        {
            svc = new C();

            result = action.Invoke(svc);

            svc.Close();
        }
        catch (FaultException ex)
        {
            // Logging goes here
            // Service Name: svc.GetType().Name
            // Method Name: action.Method.Name
            // Duration: You could note the time before/after the service call and calculate the difference
            // Exception: ex.Reason.ToString()

            if (svc != null)
            {
                svc.Abort();
            }

            throw;
        }
        catch (Exception ex)
        {
            // Logging goes here

            if (svc != null)
            {
                svc.Abort();
            }

            throw;
        }

        return result;
    }
}

And an example of its use:

var result = ServiceProxy.Execute<MyServiceClient, MyReturnType>
(
    svc => svc.GetSomething(someId)
);