Activity Diagrams Sohel Khan

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Activity DiagramsSohel Khan
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Activity Diagrams

• They represents the dynamics of a system.
• They are flow charts that are used to show the
  work flow of a system.
• They show the flow of control from activity to
  activity in the system.
• They show what activities can be done in
  parallel, and any alternative paths through the
  flow.

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Activity Diagrams cont..

• After creating a use case diagram, activity
  diagrams may be created to represent the flow
  across use cases or they may be created to
  represent the flow within a particular use case.
• Activity diagrams may also be created to show the
  workflow for an operation.

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Activity Diagrams cont..

• Activity diagrams contain
• Activities,
• Transitions between activities,
• Decision points,
• Synchronization bars.
• Input/output

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Activity

• Represented in UML by a rounded rectangle.
• Activity represents the performance of some
  behavior in the work flow.

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Components of Activity Diagrams

• Activities
• Performance of some behavior in the workflow

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Components

• Synchronization
• What activities are done concurrently.
• What activities must complete before processing
  may continue (join).

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Transitions

• Transitions are used to show the passing of the
  flow of control from activity to activity.
• They are typically triggered by the completion of
  the behavior in the originating activity.

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Components

• Transition
• Passing the flow of control from activity to
  activity

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Synchronization Bars

• In a workflow there are typically some activities
  that may be done in parallel.
• A synchronization bar allows you to specify what
  activities may be done concurrently.
• A synchronization bar may have
• many incoming transition and one outgoing
  transition, or
• one incoming transition and many outgoing
  transitions.

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Decision Points

• When modeling the workflow of a system, it is
  often necessary to show where the flow of control
  branches based on a decision point.
• The transition from a decision point contain a
  guard condition.
• The guard condition is used to determine which
  path from the decision point is taken.
• Decisions along with their guard conditions allow
  you to show alternative paths through a work
  flow.

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Components

• Decision
• Show where the flow of control branches based on
  a decision point.
• Guard condition is used to determine which path
  from the decision point is taken.

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A typical Activity Diagram for Receiving and
Dispatching Orders
Receive
Order
for each line

item on order
Cancel
Check
Authorize
Order
Line Item
Payment
failed
in stock
Assign to
Order
succeeded
need to
stock assigned to
reorder
all line items and
Reorder
payment authorised
Item
Dispatch
Order
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Activity Diagram -- example
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Input/output - sending/receiving signals
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Swimlanes

• Swimlanes may be used to partition an activity
  diagram.
• This facility allows activity diagrams to expand
  and show who has the responsibility for each
  activity in a process
• Eg- Consider a consulting firm and the business
  process involved in meeting a new client

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Swimlanes cont

• A salesperson calls the client and sets up an
  appointment.
• If the appointment is onsite, corporate
  technicians prepare a conference room for a
  presentation.
• If the appointment is offsite,a consultant
  prepares a presentation on a laptop.
• The consultant and the salesperson meet with the
  client at the agreed-upon location and time.
• The salesperson follows up with a letter.
• If the meeting has resulted in a statement of a
  problem, the consultant creates a proposal and
  sends it to the client

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Activity Diagram
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Example Swimlanes
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Registration Activity Diagram
Assign Professor
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Bank Example

• A use case is a sequence of transactions
  performed by a system that yields a measurable
  result of value for a particular actor.

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Bank Example
Next Transaction

• Activity Diagrams depicts Flow within and
  between Use Cases Multithreads can be Shown

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Activity Diagrams - Summary

• Activity diagrams describe the procedural
  possibilities of a system with the aid of
  activities.
• Activity is a single step in a procedure.
• Data and Control flow
• Parallel activities
• Synchronization
• Input/output
• Swimlanes show responsibilities