The main method that does the AOP magic

invocation_method.cs

public void Intercept(IInvocation invocation)
{
    if (Log.IsDebugEnabled) Log.Debug(CreateInvocationLogString("Called", invocation));
    try
    {
        invocation.Proceed();
        if (Log.IsDebugEnabled)
            if (invocation.Method.ReturnType != typeof(void))
                Log.Debug("Returning with: " + invocation.ReturnValue);
    }
    catch (Exception ex)
    {
        if (Log.IsErrorEnabled) Log.Error(CreateInvocationLogString("ERROR", invocation), ex);
        throw;
    }
}