public interface IMath
    {
        // Methods
        double Add(double x, double y);
        double Sub(double x, double y);

    }
   public class Math : MarshalByRefObject, IMath
    {
        // Methods
        public double Add(double x, double y) { return x + y; }
        public double Sub(double x, double y) { return x - y; }

    }
   public class MathProxy : IMath
    {
        // Fields
        Math math;

        // Constructors
        public MathProxy()
        {
            // Create Math instance in a different AppDomain
            AppDomain ad = System.AppDomain.CreateDomain("MathDomain", null, null);
            ObjectHandle o = ad.CreateInstance("TestDesgine", "TestDesgine.Math", false,
              System.Reflection.BindingFlags.CreateInstance, null, null, null, null, null);
            math = (Math)o.Unwrap();
        }

        // Methods
        public double Add(double x, double y)
        {
            return math.Add(x, y);
        }
        public double Sub(double x, double y)
        {
            return math.Sub(x, y);
        }
      
    }