Computers as Components, 2nd Edition

A.2 Diagram Types 473

A.2.3 Sequence and Collaboration Diagrams

Sequence and collaboration diagrams both illustrate scenarios,but in different ways.

Figure A.8 shows a UML sequence diagram that includes a timeline. The bars show

when different objects are active. FigureA.9 shows a UML collaboration diagram for

the same sequence of events. In this diagram,messages are given sequence numbers

to indicate time.

Time

Focus of

control

Event 2

Event 1

Event 3

:class 1

:class 2 :class 3

FIGURE A.8

A sequence diagram in UML.

2: event 2

Sequence number: operation

object 1:

Class 1

object 2:

Class 2

object 3:

Class 3

1: event 1

FIGURE A.9

A UML collaboration diagram.

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