© M.E. Fayad 2000-2005 SJSU -- CmpE L3-6b-S1 Sequence Diagrams

Software System Engineering

Dr. M.E. Fayad, Professor

Computer Engineering Department, Room #283I

College of Engineering

San José State University

One Washington Square

San José, CA 95192-0180

http://www.engr.sjsu.edu/~fayad

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S2 Sequence Diagrams

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Lesson 3-6b:Sequence Diagrams

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S3 Sequence Diagrams

Lesson Objectives

Objectives

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Understand how to generate sequence diagrams Learn the syntax of sequence diagram Explore examples of sequence diagrams

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S4 Sequence Diagrams

Place objects that participate in the interaction at the top of the diagram, across the X-axis

– Place the object that initiates the interaction at the left, and increasingly more subordinate objects to the right

Place messages the objects send and receive along the Y-axis, in order of increasing time from top to bottom 4

Drawing Sequence Diagrams

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S5 Sequence Diagrams

Use sequence diagrams to model flows of control by time ordering

– Do a better job of visualizing simple iteration and branching

Use collaboration diagrams to model flows of control by organization

– Do a better job of visualizing complex iteration and branching and of visualizing multiple concurrent flows of control 5

Common Uses

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S6 Sequence Diagrams

Sequence diagrams have two features:

– Object lifeline

• Vertical dashed line that represents the existence of

an object over a period of time

– Focus of control

• A tall, thin rectangle that shows the period of time

during which an object is performing an action,

either directly or through a subordinate procedure 6

Sequence Diagrams

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S7 Sequence Diagrams

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Syntax of Sequence Diagram

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S8 Sequence Diagrams

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Sequence Diagram: Example (1)

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S9 Sequence Diagrams

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Sequence Diagram: Example (2)

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S10 Sequence Diagrams

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Sequence Diagram: Example (3)

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S11 Sequence Diagrams

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Sequence Diagram: Example (4)

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S12 Sequence Diagrams

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Sequence Diagram: Example (5)

© M.E. Fayad 2000-2005 SJSU – CmpE --- M.E. Fayad L3-6b-S13 Sequence Diagrams

T/F:

1. The participants in the sequence diagrams are classes and components

2. The sequences in the sequence diagram are connected.

3. Sequence diagram is an event-trace diagram

4. You can generate a sequence diagram / use case.

5. A sequence diagram models flows of control by time ordering 13

Discussion Questions