Class Diagram for Example ATM System

Shown below is the class diagram for the ATM system. The basic structure of the class diagram arises from the responsibilities and relationships discovered when doing the CRC cards and Interaction Diagrams. (If a class uses another class as a collaborator, or sends a message to an object of that class during an Interaction, then there must either be an association linking objects of those classes, or linking the "sending" class to an object which provides access to an object of the "receiving" class.)

In the case of the ATM system, one of the responsibilities of the ATM is to provide access to its component parts for Session and Transaction objects; thus, Session and Transaction have associations to ATM, which in turn has associations to the classes representing the individual component parts. (Explicit "uses" links between Session and Transaction, on the one hand, and the component parts of the ATM, on the other hand, have been omitted from the diagram to avoid making it excessively cluttered.)

The need for the various classes in the diagram was discovered at various points in the design process.

That is, OO design is not a "waterfall" process - discoveries made when doing detailed design and coding can impact overall system design.

To prevent the diagram from becoming overly large, only the name of each class is shown - the attribute and behavior "compartments" are shown in the detailed design, but are omitted here.

Click on a class icon for links to further information about it

[ Class Diagram ] Class ATM Class CardReader Class CashDispenser Class CustomerConsole Class EnvelopeAcceptor Class Log Class NetworkToBank Class OperatorPanel Class ReceiptPrinter Class Session Class Transaction Class Withdrawal Class Deposit Class Transfer Class Inquiry Class Money Class Status Class Message Class Balances Class Receipt Class Card Class AccountInformation

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Copyright © 2000, 2001, 2002 - Russell C. Bjork. Permission for non-commercial reproduction for educational use is hereby granted; all other rights are reserved.