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Software EngineeringDr. K. T. Tsang

Lecture 6

Interaction Diagramshttp://www.uic.edu.hk/~kentsang/SWE/SWE.htm

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Interaction diagrams

• Sequence diagrams – ordered by time– Shows the flow of logic through a scenario

• Collaboration diagrams – shows the communications among objects– Use to assess the impact of interactions

• Activity diagrams – focuses on the flow of activities, useful for understanding complex procedures

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Sequence diagrams

• Describe the time sequence of interactions among classes

• Contain these elements:– Class roles– Lifelines– Activations– Messages

• B&R 7.2

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Example class model ..1

Project

Activity

Resource Task

1

1

1

1..*

1..*

* Assigned to

Filled diamond – composition relationship

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Example class model ..2

Skill

Resource

Hourly Salaried

Resource-Skill

*

*

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Sequence diagrams Example ..1

Res Manager Win:UserInterface :Resource :Skill :Resource-skill

:Resource Manager

Find resource by name

Find resource

Find skill

assign skill to resource

Find skill by name

Assign skill to resource

[Resource is not assigned skill]

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Proj Manager Win:UserInterface :Project :Activity :Task

:Project Manager

Find project by name

Remove project

Find activity by project

Remove task

Find task by activity

Remove activity

Remove project

No more task

No more activity

Sequence diagrams Example ..2

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Collaboration diagrams

• Describe interactions among classes and associations

• Contains these elements– Class roles– Association roles– Messages flows

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Collaboration diagrams Example ..1

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Collaboration diagrams Example ..2

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Collaboration diagrams Example: Remove project

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Activity diagrams

• Shows the sequence of steps that make up a complex process, like a flowchart

• Shows flows of control similar to a sequence diagram, but focuses on operation rather than on objects

• Each activity is represented by an elongated ovals

p.140, 7.3; p.155, 8.3 B&R

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Activity diagrams : example 1

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• Branches – Symbol : Hollow diamond– Condition [square bracket]

• Initiation & Termination – solid circle, a bull’s eye (a solid circle surrounded by a a hollow circle)

• Concurrent activities– One activity can be split into several concurrent activities

(a fork of control)– Then be combined into a single activity (a merge of

control)– A fork or a merge is shown by a synchronization bar (a

heavy line with arrows coming in or out of it)

Activity diagrams .. 2

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Activity diagrams : example 2

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• Sending & receiving signals– Convex pentagon, sending– Concave pentagon, receiving

• Swimlanes – shows organizational responsibility for activities

Activity diagrams .. 3

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Activity diagrams

Sending & receiving signals

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flight attendant Ground crew Catering

Activity diagrams: Swimlanes

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Reading for this lecture

• Chapter 7 & 8, Blaha & Rumbaugh

• Study the interaction diagrams in the examples– http://www.cs.gordon.edu/courses/cs211/

AddressBookExample/index.html– http://www.cs.gordon.edu/courses/cs211/

ATMExample/index.html