UML Sequence Diagrams Passenger w To clarify object

UML Sequence Diagrams ¨ Passenger w To clarify object interactions w To refine class interfaces : a. Ticket. Machine select. Zone() ¨ ¨ insert. Coins() ¨ pickup. Change() Used during system design ¨ Objects are represented by columns Messages are represented by arrows Activations are represented by narrow rectangles Lifelines are represented by dashed lines pick. Up. Ticket() Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Conquering Complex and Changing Systems 1

UML Sequence Diagrams: Nested Messages Passenger : a. Zone. Button select. Zone() : a. Tarif. Schedule : a. Display lookup. Price(selection) price Dataflow display. Price(price) …to be continued. . . ¨ ¨ The source of an arrow indicates the activation which sent the message An activation is as long as all nested activations Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Conquering Complex and Changing Systems 2

Sequence Diagram Observations ¨ ¨ ¨ UML sequence diagram represent behavior in terms of interactions. Complement the class diagrams which represent structure. Useful to find participating objects. Time consuming to build but worth the investment. Many tools exist to speed creation of diagrams. Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Conquering Complex and Changing Systems 3