1. Exercices & Corrections Week 3

2. Exercise (2) Abstract from the example scenarios (p10&19) and put the
Regnell’s approach in the Reference Framework

3. Regnell’s UCM (Use Case Model)
1. Withdraw Cash, normal case
Actor: ‘ATM customer’
1.IC Invocation Conditions:
1.IC.1 The system is ready for transactions.
1.FC Flow Conditions:
1.FC.1 The user’s card is valid.
1.FC.2 The user enters a valid code.
1.FC.3 The user enters a valid amount.
1.FC.4 The machine has the required amount of cash.
1.FE Flow of Events:
1.FE.1 The user inserts the card.
1.FE.2 The system checks if the card is valid.
1.FE.3 A prompt for the code is given
1.FE.4 The user enters the code.
1.FE.5 the system checks if the code is valid
1.FE.6 A prompt ‘enter amount or select balance’ is given.
1.FE.7 The user enters the amount.
1.FE.8 The system checks if the amount is valid
1.FE.9 The system collects the cash.
1.FE.10 The cash us ejected.
1.FE.11 A prompt ‘take cash’ is given.
1.FE.12 The user takes the cash.
1.FE.13 The card is ejected.
1.FE.14 A prompt ‘ take card’ is given.
1.FE.15 The user takes the card;
1.FE.16 The system collects receipt information.
1.FE.17 The receipt is printed.
1.FE.18 A prompt ‘take receipt’ is given.
1.FE.19 The user takes the receipt.
1.TC Termination condition:
1.TC.1 The system is ready for transactions.
UCM is built during the analysis phase of UORE

4. Regnell’s SUM (Synthetized Usage Model)
code
fail
ready
The SUM is constructed during
the synthesis phase
aborted
insert card
re-enter code
abort
code
invalid
account number
code
card validation
retry validation
card invalid
card ok
code ok
too many errors
aborted
The synthetized usage view for
the ‘ATM Customer’ integrates
different use case descriptions
abort
enter code
disclaim card
code
code validation
ready
aborted
code ok
enter amount
or select balance
User action
amount
amount
invalid
...
amount validation
abort
System action
amount ok
...
take card
message
ready

5. Exercise (2) Regnell’s UORE (Usage Oriented Requirements Engineering)
Form.Desc.Medium: Graphics(SUM), Text (UCM)
Form.Desc.Notation: Semi-formal
Form.Present.Anim: False
Form.Present.Interac: None
Content.Abstraction: Type
Content.Context : Syst. Interaction, Syst. Internal
Coverage.Func.: S, F, B
Coverage.Intent.: Goal
Coverage .Non Func.: False
Content.Argumentation: False
Purpose: Descriptive
Life cycle. Duration: Persistent
Life cycle.Op.: Capture, Integration

6. Exercise (3) You have been hired to create the requirements document
for a new ATM. Decide whether each item in the following list is
a stakeholder, a primary actor, a secondary actor, the SuD, or
not an actor at all:
The ATM
The customer
The ATM card
The bank
The front panel
The bank owner
The serviceman
The printer
The bank clerk
The main bank computer system
The bank robber
List the primary actors

7. Exercise (3) Decide whether each item in the following list is
a stakeholder, a primary actor, a secondary actor, the SuD, or
not an actor at all:
The ATM : the SuD
The customer : a primary actor
The ATM card : not an actor, a resource
The bank : not an actor,
The front panel : not an actor ; a component of the SuD
The bank owner : a stakeholder (probably!)
The serviceman : a primary actor
The printer : not an actor; a component of the SuD
The bank clerk : a primary actor (who refills the cash?)
The main bank computer system : a secondary actor
The bank robber : use your imagination!!!!!
List the primary actors
The customer, the serviceman, the bank clerk

8. List goals that the various ATM primary actors will have
Exercise (4)
List goals that the various ATM primary actors will have
with respect to the ATM

9. Exercise (4) Serviceman Put ATM in working order Run ATM self test
Bank clerk
Restock money
Refill supplies
Customer
Withdraw cash
Deposit money
Transfer money
Check balance

10. Write the base scenario for the use case Withdraw Money
Exercise (5)
Write the base scenario for the use case Withdraw Money
Using Fast Cash Option

11. Withdraw Money Using Fast Cash Option
Exercise (5)
Withdraw Money Using Fast Cash Option
The customer runs card through the card reader; the ATM checks
the validity of the card and if the card is valid, the ATM sends a prompt for PIN
to the customer. The customer enters the PIN. If the PIN is valid, the
ATM displays a table of possible amounts. The customer selects a withdrawal
amount. If the system authorizes the amount, it delivers the card and the cash.

12. Exercise (6)
1- Brainstorm about possible conditions for failure in the use case
Withdraw Money
2- List failure scenarios and Name them
3- Identify circumstances and outcome for each of them
4- Write the failure scenario comprising three wrong captures of
the customer’s PIN

13. Exercise (6) Possible failure conditions - an expired card
- not an ATM card
- incorrect PIN
- no credit
2- List failure scenarios
- Withdraw Money with expired card
- Withdraw Money with invalid card
- Withdraw Money with incorrect PIN
- Withdraw Money with no credit

14. Exercise (6) 3. Circumstances & outcome
- Withdraw Money with expired card
circumstances : the customer has an expired card
outcome : card
- Withdraw Money with incorrect PIN
circumstances : the customer has a valid card but not the PIN
outcome : “your card has been swallowed : please, contact your bank agency”

15. Withdraw Money with incorrect PIN
Exercise (6)
Withdraw Money with incorrect PIN
The customer runs card through the card reader; the ATM checks
the validity of the card and if the card is valid, the ATM sends a prompt for PIN
to the customer. The customer enters the PIN. If the PIN is not valid, the
ATM sends again a prompt for PIN to the customer. The customer enters the
PIN. If the PIN is not valid, the ATM sends a third time a prompt for PIN
to the customer. The customer enters the PIN. If the PIN is not valid, the ATM
swallows the card and displays a message “your card has been swallowed,
please contact your bank agency”

16. Exercise (7)
1- Brainstorm about possible variations of the course of actions in
the base success scenario of the use case Withdraw Money
2- List variant scenarios and Name them
3- Identify circumstances and outcome for each of them
4- Write the variant scenario comprising two wrong captures of
the customer’s PIN

17. Exercise (7) Possible variations of the normal course of actions
- two captures of incorrect PIN
- customer asks for a receipt
2- Name variant scenarios
- Withdraw Money with a receipt
- Withdraw Money with two captures of incorrect PIN
3- Outcome & circumstances
Withdraw Money with a receipt
circumstances : the customer has a valid card and credit on
her account
outcome : cash, receipt and card

18. Withdraw Money with two captures of incorrect PIN
Exercise (7)
Withdraw Money with two captures of incorrect PIN
The customer runs card through the card reader; the ATM checks
the validity of the card and if the card is valid,
the ATM repeats at maximum twice and till the PIN is valid,
a prompt for PIN is sent to the customer.
the customer enters the PIN.
If the PIN is valid, the ATM displays a table of possible amounts.
The customer selects a withdrawal amount. If the system accepts the amount,
it delivers the card and the cash.