Using your knowledge of how an ATM is used, develop a set of use cases that could serve as a basis for understanding the requirements for an ATM system.

What will be an ideal response?

There are a variety of different types of ATM so, obviously, there is not a definitive
set of use cases that could be produced. However, I would expect to see use cases
covering the principal functions such as withdraw cash, display balance, print
statement, change PIN and deposit cash. The use case description should describe
the actors involved, the inputs and outputs, normal operation and exceptions.
Withdraw cash:
Actors: Customer, ATM, Accounting system
Inputs: Customer’s card, PIN, Bank Account details
Outputs: Customer’s card, Receipt, Bank account details
Normal operation: The customer inputs his/her card into the machine.
He/she s promoted for a PIN which is entered on the keypad. If correct,
he/she is presented with a menu of options. The Withdraw cash option is
selected. The customer is promoted with a request for the amount of
cash required and inputs the amount. If there are sufficient funds in
his/her account, the cash is dispensed, a receipt if printed and the
account balance is updated. Before the cash is dispensed, the card is
returned to the customer who is prompted by the machine to take their
card.
Exception: Invalid card. Card is retained by machine; Customer advised to
seek advice.
Incorrect PIN. Customer is request to rekey PIN. If incorrect after 3
attempts, card is retained by machine and customer advised to seek
advice.
Insufficient balance Transaction terminated. Card returned to customer.
Display balance:
Actors: Customer, ATM, Accounting system
Inputs: Customer’s card, PIN, Bank Account details
Outputs: Customer’s card
Normal operation: The customer authenticates using card and PIN as in
Withdraw cash and selects the Display Balance option. The current
balance of their account is displayed on the screen. The card is returned
to the customer.
Exception: Invalid card. As in Withdraw cash
Incorrect PIN. As in Withdraw cash
Print statement:
Actors: Customer, ATM, Accounting system
Inputs: Customer’s card, PIN, Bank Account details
Outputs: Customer’s card, Printed statement
Normal operation: The customer authenticates using card and PIN as in
Withdraw cash and selects the Print statement option. The last five
transactions on their account is printed. The card is returned to the
customer.
Exception: Invalid card. As in Withdraw cash
Incorrect PIN. As in Withdraw cash
Change PIN:
Actors: Customer, ATM
Inputs: Customer’s card, PIN
Outputs: Customer’s card
Normal operation: The customer authenticates as in Withdraw cash and
selects the Change PIN option. He/she is prompted twice to input the
new PIN. The PINS input should be the same. The customer’s PIN is
encrypted and stored on the card. Card returned to customer.
Exception: Invalid card. As in Withdraw cash.
Incorrect PIN. As in Withdraw cash.
PINS do not match. The customer is invited to repeat the process to reset
his/her PIN.
Deposit cash:
Actors: Customer, ATM, Accounting system
Inputs: Customer’s card, PIN, Bank Account details, Cash to be

deposited

Outputs: Customer’s card, Receipt
Normal operation: The customer authenticates as in Withdraw cash and
selects the Deposit option. The customer is promoted with a request for
the amount of cash to be deposited and inputs the amount. He or she is
then issued with a deposit envelope in which they should put the cash
then return it to the machine. The customer’s account balance is updated
with the amount deposited but this is marked as uncleared funds and is
not cleared until checked. A receipt is issued and the customer’s card is
returned.
Exception: Invalid card. As in Withdraw cash.
Incorrect PIN. As in Withdraw cash.
No cash deposited within 1 minute of envelope being issued. Transaction
terminated. Card returned to customer.