CPSC333 SENG311: Foundations Principles of SE

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CPSC333 / SENG311 Foundations / Principles of SE

• Activity Diagrams

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Activity Diagrams

• Things to note
• branch / merge
• synchronization bars
• fork / join
• swim lanes
• object flow

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Activity diagrams

• Used to describe
• workflow
• parallel processing
• Activities
• conceptual task to be done
• specification/implementation method of a class
• Similar to Petri nets

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Activity Diagrams

• Special type of state diagram
• Contains
• start state
• stop state
• activities
• triggerless transitions unless otherwise stated
  (for branches), once an activity is completed,
  the next sequential activity commences

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Structure of activity diagrams
Activity
Activity
Activity
synchronization condition
synchronization condition
Activity
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Synchronization Bars(Forks and Joins)

• Thick horizontal or vertical bar that signifies
  parallel or concurrent processes.
• Fork a single flow splits into 2 or more flows
  of parallel activities
• Join 2 or more flows recombine into a single
  flow of activities
• Note number of processes out of a fork must
  equal the number of processes into its
  corresponding join.

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Example of activity diagrams

• The Coffee Pot

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Activity diagram
Find coffee
Put coffee
Add water
in filter
to reservoir
Put filter
in machine
Turn on
machine
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Conditions in activity diagrams
Find coffee
Branch
unguarded transition
Put coffee
Check water
in filter
in reservoir
not enough water
Put water in the reservoir
Put filter
in machine
else
filter with coffee in machine and reservoir
contains water
Turn on
machine
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Branch and Merge

• A branch is used to model a decision point
  (if/then/else).
• A branch point can have several branches, all of
  whose guard conditions must be mutually
  exclusive, to avoid program freeze.
• Branch conditions must also cover the complete
  set of values for its data world (e.g. one branch
  for lt 12, and the other for gt12)
• A merge collects all branch points, marking the
  end of the branch. This is optional.

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Structure of activity diagrams
condition 1
Activity
condition 2
Activity
Activity

• Strictly UML
• forks ? joins
• branch ? merge
• No synchronization condition

synchronization condition
Activity
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Swim Lanes
Customer
Sales
Warehouse
Request product

• Identify responsibilities
• ExampleModeling workflows for business units

Process order
Pull material
Ship order
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Object flow
Customer
Sales
Warehouse
Request product

• Shows output objects and (optionally) their state

Process order
Pull material
oOrder in progress
Ship order
oOrder send
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Swim Lanes

• Swim lanes are used to identify the roles, teams,
  groups, or even specific individual objects
  responsible for specific activities. Each lane is
  labeled with a specific role or object.
• Activities are still in the same order, but are
  drawn under their executors lane.
• Use synchronization bars to show more than one
  role working on a single activity.

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Object Flow

• Object flow specifies the artifact or product of
  a certain activity.
• Represented as a dependency from the activity to
  the object.
• An object could be associated with several
  activities, showing the objects state
  transitions as it goes through the activities.

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Proposed Exercise

• Define an activity diagram for preparing your
  breakfast
• Define an activity diagram for your software
  development process that includes the object flow

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Were Available!

• Questions?
• if you have any questions about contents of this
  lecture or other course-related issues, please
  come by during our office hours, or send us email
• Dr. Joshua MWF, 12-1pm, ICT 548
• joshuar_at_cpsc.ucalgary.ca
• Dr. Walker WF, 1-2pm, ICT 546
• rwalker_at_cpsc.ucalgary.ca