CPSC 333: Foundations of Software EngineeringJ. Denzinger Small Test: Bank account manager System has to run on an automated teller machine. User must be able to deposit checks into the account. User must be able to draw money from the account. User should be able to query the balance of his/her account. The user should get a receipt for a transaction on request. The transaction type (withdrawal or deposit), the transaction date, the account number, the amount, and the new balance should be visible on the receipt. After each transaction the new balance should be displayed to the user.

CPSC 333: Foundations of Software EngineeringJ. Denzinger Errors regarding arrows (connections) connection between actors and use cases have no direction Connections between use cases are dotted () and should be labeled > or > >: arrow points from use case describing the alternative event flow to the “standard” case >: arrow points from “calling” use case to use case that describes actions to include

CPSC 333: Foundations of Software EngineeringJ. Denzinger Errors regarding relation graphics and description If use cases are connected then in the textual description we have to “mirror” this: > … - include (verify user) … > … - (print receipt)...

CPSC 333: Foundations of Software EngineeringJ. Denzinger Errors regarding textual descriptions of use cases Preconditions not given No connection to graphical representation Different names in graphical and textual representation: user vs visitor use case name different bank info vs user info But also: use case name appearing several time in diagram

CPSC 333: Foundations of Software EngineeringJ. Denzinger Other often occuring errors Flow charts instead of use cases remember: use case = sequence of actions achieving a goal not: action = use case Exceptional flow: not only exception condition, but also actions if it occurs Exceptional flow: indicate in main flow at which point to check for this exception (if not obvious)!

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (1): User withdraw deposit check balance Verify user > withdraw with receipt deposit with receipt > ( print receipt)

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (2): Use case: withdraw Precondition: User has selected withdraw option Main flow: Include (Verify user) Prompt user for amount to withdraw Check available funds of user Check available money of ATM Remove amount from account Give money (print receipt) Print current balance Exceptional flow If not sufficient funds or money available, prompt user for lower amount

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (3): Use case: deposit Precondition: User has selected deposit option Main flow: Include (Verify user) Prompt user for amount of deposit Open slot Get check (print receipt) Print (balance + deposited amount)

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (4): Use case: check balance Precondition: User has selected balance option Main flow: Include (Verify user) Print balance

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (5) (not required in test): Use case: verify user Precondition: none Main flow: User enters ID card User enters PIN number System checks validity of card and number Exceptional flow: If combination is not valid, reject user

CPSC 333: Foundations of Software EngineeringJ. Denzinger Good solution (6) (not required in test): Use case: withdraw with receipt Precondition: User has selected withdraw option and print receipt option … Use case: deposit with receipt Precondition: User has selected deposit option and print receipt option...

CPSC 333: Foundations of Software EngineeringJ. Denzinger Acceptable solution (1): User withdraw deposit check balance withdraw with receipt deposit with receipt > ( print receipt)

CPSC 333: Foundations of Software EngineeringJ. Denzinger Acceptable solution (2): Use case: withdraw Precondition: User is verified and has selected withdraw option … Similar for other use cases