public class A
    {
        internal protected virtual void YoBusiness()
        {
            //do something
        }

        public void test() { }
    }


    class B
    { // not a derived class - just composites an instance of A
        public B()
        {
            A a = new A();
            a.YoBusiness(); // Thanks friend for the access!
        }
    }


    class D : A
    {  // derived across assemblies
        internal protected override void YoBusiness()
        {
            // Hey thanks other guy, I can provide a new implementation.
        }
    }

class C : A
    {  // derived across assemblies
        public C()
        {
            YoBusiness();
        }

        protected override void YoBusiness()
        {
            // Hey thanks other guy, I can provide a new implementation.
        }
    }

abstract class Job
{
  public abstract void Run()

  protected internal Context RunContext{get; internal set}
}