AppendixObject-Oriented Analysis and Design:

Sequence Diagrams and Activity Diagrams

Modern Systems Analysisand Design

Fifth Edition

Jeffrey A. Hoffer Joey F. George

Joseph S. Valacich

© 2008 by Prentice Hall 2Chapter 8 Appendix

Learning Objectives

Understand how to represent system logic with sequence diagrams.

Understand how to represent system logic with activity diagrams.

Dynamic Modeling: Sequence Diagrams

Sequence diagram: depicts the interactions among objects during a certain periods of time.

May be presented either in a generic form or in an instance form.

Generic form shows all possible sequences of interactions – sequences corresponding to all the scenarios of a use case.

Instance form shows the sequence for only one scenario.

Chapter 8 Appendix 3© 2008 by Prentice Hall

Dynamic Modeling: Sequence Diagrams (Cont.)

Elements of a sequence diagram Objects: represented by boxes at top of

diagram. Lifeline: the time during which an object

exists. Messages: means by which objects

communicate with each other.

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Dynamic Modeling: Sequence Diagrams (Cont.)

Activation: the time period during which an object performs an operation.

Synchronous message: a type of message in which the caller has to wait for the receiving object to finish executing the called operation before it can resume execution itself.

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Dynamic Modeling: Sequence Diagrams (Cont.)

Simple message: a message that transfer control from the sender to the recipient without describing the details of the communication.

Asynchronous message: a message in which the sender does not have to wait for the recipient to handle the message.

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Designing a Use Case with a Sequence Diagram

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Figure 8-11 Sequence diagram for a class registration scenario without prerequisites

Designing a Use Case with a Sequence Diagram

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Figure 8-12 A generic sequence diagram for the “Prerequisite Courses Not Completed” use case

A Sequence Diagram for Hoosier Burger

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Figure 8-13 Sequence diagram for Hoosier Burger’s Hire Employee use case

Process Modeling: Activity Diagrams Activity Diagrams: shows the conditional

logic for the sequence of system activities needed to accomplish a business process.

Clearly shows parallel and alternative behaviors.

Can be used to show the logic of a use case.

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Process Modeling: Activity Diagrams (Cont.)

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Figure 8-14 Activity diagram for a customer order process.

Process Modeling: Activity Diagrams (Cont.) Elements of Activity Diagrams:

Activity: a behavior that an object carries out while in a particular state.

Transition: a movement from one activity or state to another.

Branch: a diamond symbol containing a condition whose results provide transitions to different paths of activities.

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Process Modeling: Activity Diagrams (Cont.)

Synchronization bar: horizontal or vertical bars denoting parallel or concurrent paths of activities.

Fork: the beginning of parallel activities. Join: the end of parallel activities.

Swimlanes: columns representing different organizatonal units of the system.

Chapter 8 Appendix 13© 2008 by Prentice Hall

Summary In this appendix you learned how to: Understand how to represent system

logic with sequence diagrams. Understand how to represent system

logic with activity diagrams.

Chapter 8 Appendix 14© 2008 by Prentice Hall