Faults ofthe drinks 4istributor Go back to the study of a drinks distributor, looking at the global behavioral graph (see Figure 3.7).

1. Imagine several types of functional and hardware faults and show how they transform the graph. What failures do they lead to?

2. Which type of faults (and on which part of the graph) affect the user's satisfaction by altering the functioning of the money management

(accepting and giving back coins)?

3. Find a functional transformation which allows this distributor to serve several drinks with the same initial amount of money or to give the change back by pressing on Cancel (you can add a Return-Money button).