Need help on setting Unity interception

Question

First, I never used Unity before... I want to introduce Tracing / Logging to our project through unity interception.
The project is considerably big (~30000 files). The goal is to trace performance / execution period every time we try to call outside service. Regrettably I cannot use any other library.
To get familiar with how this concept is going to work, I built a small program that I found on MSDN; however my interception with log attribute still does not fire. I am sure I am missing some configuration or / and initialization. I appreciate any help.

Here is my Main program:

namespace calc
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                var t = new calc.Calculator.Calculator().Sub(5, 8);
            }
            catch (Exception ex)
            {
                System.Console.WriteLine(ex.Message);
            }
        }
     }
}

Here is Calculator class:

namespace calc.Calculator
{
    public interface ICalculator
    {
        Int32 Sum(Int32 x, Int32 y);        
        Int32 Sub(Int32 x, Int32 y);
    }

    public class Calculator : ICalculator
    {        
        public Int32 Sum(Int32 x, Int32 y)
        {
            return x + y;
        }

        [NonNegativeCallHandler] // Intercept this method and run tracing on it
        public Int32 Sub(Int32 x, Int32 y)
        {
            return x - y;
        }
    }
}

Here is my CallHandler:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.Unity.InterceptionExtension;

namespace calc.Tracing
{
    public class NonNegativeCallHandler : ICallHandler
    {
        public IMethodReturn Invoke(IMethodInvocation input,
                                GetNextHandlerDelegate getNext)
        {
            // Perform the operation
            var methodReturn = getNext().Invoke(input, getNext);

            // Method failed, go ahead
            if (methodReturn.Exception != null)
                return methodReturn;

            // If the result is negative, then throw an exception
            var result = (Int32)methodReturn.ReturnValue;

            if (result < 0)
            {
                var exception = new ArgumentException("...");
                var response = input.CreateExceptionMethodReturn(exception);

                // Return exception instead of original return value
                return response;
            }

            return methodReturn;
        }

        public int Order { get; set; }
    }
}

And Finally

*Here is my Attribute definition:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.Unity.InterceptionExtension;
using Microsoft.Practices.Unity;

namespace calc.Tracing
{
     public class NonNegativeCallHandlerAttribute : HandlerAttribute
     {
         public override ICallHandler CreateHandler(IUnityContainer container)
         {
             return new NonNegativeCallHandler();
         }
     }
}

What else exactly I need to add, and where (config file or inside constructor, etc..) in order for this code to work.

Answer 1

I found one of the solutions... I've modified my program class to register container.. And it looks like no additional configuration is required at all. Here is modified program:

namespace calc
{
class Program
{
    static void Main(string[] args)
    {
        ICalculator iCal;
        try
        {

            iCal = ConfigurePolicyInjectionWithUnity();

            var t = iCal.Sub(8, 5);
        }
        catch (Exception ex)
        {
            System.Console.WriteLine(ex.Message);
        }
    }

    static ICalculator ConfigurePolicyInjectionWithUnity()
    {
        IUnityContainer container = new UnityContainer();

        container.AddNewExtension<Interception>();
        container.RegisterType<ICalculator, 
                           calc.Calculator.Calculator>().Configure<Interception>()
            .SetInterceptorFor<ICalculator>(new InterfaceInterceptor());

            // resolve
            return container.Resolve<ICalculator>(); ;
        }
    }
}

Now, here is the question... Lets say that I have about 20 different flavors of calculators each class has about 3 - 4 methods to be traced. Each of those methods have unique signatures. So 3-4 methods x 20 classes = ~80 methods with unique signatures to be traced. What I am leading to is that I cannot have single interface to describe all these methods... From the solution above, at least in my case, it looks like I must have an interface per class in order to implement interceptor. This does not look very elegant to introduce 20-30 new interfaces just to have logging. In this case, there is no difference between using interception and just having some helper class to do logging. Am I correct?

Is there any other way I can use interception without defining interface? All I need is to be able to Log time when methods start running and the time when they complete execution.

Any help or ideas would be appreciated.

Answer 2

Your code looks like it origins from this article by Dino Esposito. Looks like you missed the section on configuration (paragraphs Using Fluent Code or Adding Policies through configuration).

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Update

Did you have a look at this page on MSDN?