Facade Pattern

    class SubsystemOne
    {
        public void A1Method()
        {
            Console.WriteLine("OP-A1 of SubsystemOne is called.");
        }
        public void A2Method()
        {
            Console.WriteLine("OP-A2 of SubsystemOne is called.");
        }
    }

    class SubsystemTwo
    {
        public void B1Method()
        {
            Console.WriteLine("OP-B1 of SubsystemTwo is called.");
        }

        public void B2Method()
        {
            Console.WriteLine("OP-B2 of SubsystemTwo is called.");
        }
    }

    class SubsystemThree
    {
        public void C1Method()
        {
            Console.WriteLine("OP-C1 of SubsystemThree is called.");
        }

        public void C2Method()
        {
            Console.WriteLine("OP-C2 of SubsystemThree is called.");
        }
    }

    public class Facade
    {
        SubsystemOne objectOne = new SubsystemOne();
        SubsystemTwo objectTwo = new SubsystemTwo();
        SubsystemThree objectThree = new SubsystemThree();

        public void OperationOne()
        {
            Console.WriteLine("*** Operation One ***");
            objectOne.A1Method();
            objectOne.A2Method();
            objectTwo.B1Method();
        }
        public void OperationTwo()
        {
            Console.WriteLine("*** Operation Two ***");
            objectTwo.B2Method();
            objectThree.C1Method();
            objectThree.C2Method();
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Facade facade = new Facade();

            facade.OperationOne();

            Console.ReadKey();
        }
    }