UML State Machine Diagrams

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UML State Machine Diagrams

• CS2335
• Spring 2006

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Agenda

• State Machine Diagram Symbology
• State Machine Diagram Exercise

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State Machine Diagrams

• Describe how an objects (classs) state changes
  in response to external events
• State diagrams derived from Harels statecharts,
  now called Statechart
• Allow embedded state machines to account for
  state-space explosion
• Make one per CLASS or one for SYSTEM
• Use state diagrams for external events, use
  interaction (Sequence) diagrams for internal
  events (messages).

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State Machine Key Terms

• State
• Transition
• Activity
• entry, exit, do, include, internal_event
• Action
• Event

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State Machine Symbology
Normal State
Start/Initial State
Stop/Accepting/Final State
Transition
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Transition Text Syntax
EventName(parameter list) Guard / Action
Special Events After x seconds When (time1200)
Special Guards in StateName not in
StateName
right-mouse-down (location) location in window
/ object pick-object (location)
object.highlight ()
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Basic State Machine, Order Entry
Not all items checked / getNextItem
All items checked All items available
do/initiate delivery
do/check item
All items checked Some items not in stock
transhipped
cancelled
Item Received Some items not In stock
cancelled
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Another Sample State Machine
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Order Entry With Concurrency
Ordering
waiting
OUT
IN
IN
checking
shipping
OK
authorizing
authorized
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Lab 3 State Machine Exercise