UML State Diagrams

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UML State Diagrams

• CS2335
• Fall 2001

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Agenda

• Lab 4/5 Due Thursday
• Midterm Grades
• Next Lab Team Selection
• Statecharts
• Statechart Exercise

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Statecharts/ State Diagrams

• Describe how an objects state changes in
  response to external events
• State diagrams derived from Harels statecharts
• Allow embedded state machines to account for
  state-space explosion

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State Diagram Key Terms

• State
• Transition
• Activity
• Action
• entry, exit, do,include
• 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 Guard / Action
Special Guards in StateName not in
StateName
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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
checking
shipping
authorizing
authorized
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Lab 4 State Machine Exercise