Activity Diagrams

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Activity Diagrams
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Terms Concepts

• Shows flow from activity to activity
• activity - non-atomic execution
• result in some action
• calling another operation
• sending a signal
• creating and/or destroying an object
• computation
• graphically - collection of vertices edges

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• Common properties
• same as other diagrams
• contents
• activity states action states
• transitions
• objects
• action states activity states
• action state - executable atomic operation
• UML icon lazenge (horizontal top bottom with
  convex sides)
• cannot be decomposed
• atomic
• execution time - insignificant

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• Activity states
• can be decomposed
• can be represented by other activity diagrams
• not atomic ? can be interrupted
• execution time significant
• predefined states
• start state
• stop state
• transitions
• when activity or action finishes - flow of
  control passed to next state or activity
• illustrated using a transition
• triggerless since automatically transition to
  next state without a trigger

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• Branching
• represented by a diamond
• boolean expression on each outgoing transition
• not overlap but cover all possibilities
• else - signifies default if no boolean expression
  is satisfied

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• Forking joining
• synchronization bar - thick horizontal or
  vertical line
• fork - 1 incoming transition at least 2
  outgoing transitions representing concurrent
  flows of control
• join - synchronization of 2 or more concurrent
  flows of control
• 2 or more incoming transitions 1 outgoing
  transition where incoming flows wait until all of
  them reach the synchronization bar

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Prepare for
Prepare for
speech
speech
Decompress
Decompress
Gesture()
Gesture()
Stream audio()
Stream audio()
Synch mouth()
Synch mouth()
Cleanup
Cleanup
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• Swimlanes
• useful to divide activity states into groups
  where all activity states in a group have a
  common characteristic
• group - called swinlane
• has unique name
• every activity - in exactly 1 swimlane
• transition may cross swimlanes

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Customer
Sales
Warehouse
Request
Request
product
product
Process order
Process order
Pull materials
Pull materials
Ship order
Ship order
Receive order
Receive order
Bill customer
Bill customer
Pay bill
Pay bill
Close order
Close order
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• Common uses
• model dynamic aspects of system
• usually viewing entire system
• modeling a workflow from viewpoint of actor
• model business processes involving system
• model an operation
• use like a flowchart