(Homework policy: Late homeworks will not be accepted.)

Five Questions

1. Draw a data flow diagram (DFD) that specifies a reasonable set of functions, data stores, inputs, outputs, and data flows for part of a credit card system that handles transactions for retail stores. For example, a transaction might consist of buying a backpack and cross-country skiis at REI. Your part should include functions for retrieving and checking a credit card record for a customer, approving and recording each transaction, and maintaining a log of transactions for each retail outlet. The system should maintain files of credit card holders, current transactions, and accounts payable (approved transactions) for each outlet.

2. Text, p.245, Question 5.64.

3. Augment the Business Traveller ER diagram to include a class of travellers who are also wine connoisseurs. This group is interested in wines from certain countries of the world, that are made from particular grape varieties.

4. Text, p.244, Question 5.52.

5. Suppose that a vending machine dispenses champagne and fois gras, costing 25 euros and 50 euros, respectively. The machine accepts 10 and 25 euro bills as input, and returns change in units of 1, 5, 10, and 25 euro bills. Give an extended state machine that models the behavior of this vending machine. The machine has transitions of the form : G -> I / A / O. Inputs are ten-in, twenty-five-in, champagne-request, fois-gras-request, and cancel. Outputs are champagne, fois-gras, one-euro, five-euro, ten-euro, twenty-five-euro, and beep. A beep is an indicator that more money must be inserted for the particular selection made