Modeling Behavior with UML

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Modeling Behavior with UML

• CS 3300
• Fall, 2000

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Overview

• Sequence diagrams
• Activity diagrams
• Summary

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UML Sequence Diagrams

• In requirements analysis
• To refine use case descriptions
• to find additional objects (participating
  objects)
• In system design
• to refine subsystem interfaces
• Columns classes
• Arrows messages
• Narrow rectangles activations
• Dashed lines lifelines

selectZone()
insertCoins()
pickupChange()
pickUpTicket()
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UML Sequence Diagrams Nested Messages
ZoneButton
to be continued...

• The source of an arrow indicates the activation
  which sent the message
• An activation is as long as all nested activations

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Figure 2-29. Example of a sequence diagram
setting the time on 2Bwatch.
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Figure 2-30. Examples of conditions and iterators
in sequence diagrams.
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Sequence Diagram Observations

• UML sequence diagram represent behavior in terms
  of interactions.
• They complement class diagrams, which represent
  structure.
• Useful for finding participating objects.
• Time-consuming to build but worth the investment
  where interactions are complex.

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Figure 2-31. A UML statechart diagram for the
Incident class.
Active
Inactive
Closed
Archived
incidentHandled
incidentDocumented
incidentArchived
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Figure 2-32. Statechart diagram for 2Bwatch set
time function.
pressButtonsLAndR
after 2 min.
pressButtonsLAndR/beep
after 20 years
after 20 years
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Figure 2-33. Internal transitions associated with
the SetTime state (UML statechart diagram).
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Figure 2-34. Refined statechart associated with
the SetTime state (UML statechart diagram).
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Activity Diagrams

• An activity diagram shows flow control within a
  system
• An activity diagram is a special case of a state
  chart diagram in which states are activities
  (functions)

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Activity Diagrams

• Two types of states
• Action state
• Cannot be decomposed any further
• Happens instantaneously with respect to
• level of abstraction used in the model
• Activity state
• Can be decomposed further
• Activity is modeled by another activity diagram
• (cf. DFDs?)

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Activity Diagram Modeling Decisions
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Activity Diagrams Modeling Concurrency

• Synchronization of multiple activities
• Splitting the flow of control into multiple
  threads

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Activity Diagrams Swimlanes

• Actions may be grouped into swimlanes to denote
  the object or subsystem that implements the
  actions.

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Report

Emergency
Dispatcher
OpenIncident
FieldOfficer
AllocateResources
ArchiveIncident
ManageUsers
Librarian
SysAdmin
SearchArchive
ManageTerminals
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Summary

• UML provides a wide variety of notations for
  representing many aspects of software
  development
• We concentrate only on a few notations
• Functional model use case diagram
• Object model class diagram
• Dynamic model sequence diagrams, statechart and
  activity diagrams
• UML is not a methodology, but the textbook
  describes a methodology that uses UML