Mediator Flyweight ATC, Keyed Registry

Lab Assignment

1. ATC. Review the code for the Mediator-based Air Traffic Controller (ATC) example and Flyweight example.

   Modify the code for the ATC example to use flyweight design pattern as follows. Every flight has an intrinsic flyweight portion in the form of the airline logo. The logo is a text of the airline name in CAPITAL LETTERS. Note that the logo may be shared by several flights of the same airline. Modify the ATC example such that after getting clearance and acknowledging takeoff/landing, there is an extra printout (with the logo) of the aircraft actually doing the takeoff/landing.

   If the airline is AirFrance, the pilot should say "Au Revoir" before takeoff.

   Here is an example dialogue (user input is in bold):

     JetBlue487 requesting landing
     Iberia53 requesting takeoff
     Delta703 requesting landing
     AirFrance794 requesting takeoff
     Tower: Delta703 clear to land
     Delta703 roger that, landing
     ...DELTA703 lands...
     LuftHansa822 requesting takeoff
     Tower: Iberia53, clear to takeoff
     Iberia53 roger that, taking off
     ...IBERIA53 takes off...
     Tower: 
   

2. Registry. Review the registry-based implementation for Observer and Prototype. Note that in the classic Registry Design Pattern, the entry is looked up by key rather than by pointer. In the Prototype implementation, the lookup is by key. In the Observer implementation, the lookup is by pointer. Using the Prototype implementation as an example, modify the Observer implementation of the registry so that the observers may subscribe to and unsubscribe from messages in subjects by the subject's names rather than pointers. Modify the demonstration code in main() to showcase this behavior.