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ATM User Interface Design
Requirements
A statement of requirements for a portion of the system may be extracted from the use cases and other Inception documents. A brief narrative is useful for identifying the problem domain objects (concepts).
A bank customer is able to access his or her account using an automatic teller machine. To be able to use an ATM a customer must first register an account number and a passcode number. The customer’s information is then added to a list of registered users. The ATM user interface consists of a keypad, a display window, a selection of choice options, and a help screen that displays instructions for completing an ATM transaction. Users are asked to enter their account number from the keypad followed by their passcode. If the customer is a valid user, instructions are given for choosing a transaction. During a transaction, the user’s account is accessed and updated. Upon completion of a transaction, the user may elect to make another transaction or to quit.
This prototype simulates the actual machine that includes a card reader and buttons implemented in the hardware.
Identify the noun phrases and verb phrases in the narrative
A bank customer is able to access his or her account using an automatic teller machine. To be able to use an ATM a customer must first register an account number and a passcode number. The customer’s information is then added to a list of registered users. The ATM user interface consists of a keypad, a display window, a selection of choice options, and a help screen that displays instructions for completing an ATM transaction. Users are asked to enter their account number from the keypad followed by their passcode. If the customer is a valid user, instructions are given for choosing a transaction. During a transaction, the user’s account is accessed and updated. Upon completion of a transaction, the user may elect to make another transaction or to quit.
Implementation of a Prototype
To provide an illustration of the ATM user interface, we will implement an Applet that uses stubs to represent the Account, UserList, and CustomerInfo objects.
The prototype shows a working model of the user interface with the message sequence that the customer will encounter. The purpose of the prototype is to examine the human factors issues relating to the interface and to make certain that there are no deadlocks or partial cycles and that each transaction will properly terminate and return the system to the welcome state.
Test Plan for the User Interface Prototype
Test Plan for the Interface Prototype
1. Specify the paths through the system to be tested
Welcome screen (ask for Account Number) (DIGITS + ENTER) à
Passcode State (Ask for Passcode) (DIGITS + ENTER) à
Select State (Show Options) (DEPOSIT or WITDRAW + ENTER) à
Deposit State or Withdraw State (Key-in amount and press ENTER) à
Other State (Ask if user wants to make another transaction) (CLEAR = NO) à
Goodbye screen (if answer is NO) (CLEAR) à
Welcome screen is returned
Alternative paths from Select State