UML Sequence Diagrams Use Case Diagrams

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UML Sequence Diagrams Use Case Diagrams

• CS2335
• Summer 2002

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Agenda

• Sequence Diagram Example
• Use Case Principles
• Use Case Notation
• Use Case Elaboration
• Lab 4 Use Case Example

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Using Rational Rose
Baird Sun Cluster From csh source
/usr/local/rational/rs_setup.csh rose
May also use dia, argo, objecteering
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Model and View Diagrams
Implementation View
Class Diagram Object Diagram
Component Diagrams
Structural View
User View Use Case Diagrams
Deployment Diagram
Sequence Diagram Collaboration Diagram Statechart
Diagram Activity Diagram
Behavioral View
Environment View
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Sequence Diagram (Basic)
Swimlane
Object Class or Actor
name
Focus of Control/ Activation
message
Object Destruction/ Termination
X
ltltcreategtgt ltltdestroygtgt
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Sequence Diagram (Basic) Example
aClass Class
Register
adjustRoom
checkRooms
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Sequence Diagram (Hints)

• Can show either objects or processes
  (ltltprocessgtgt) in swimlanes
• Use multiple diagrams to show variations
• Use advanced features sparingly to keep diagram
  understandable

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Lab 4 Exercise
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Use Case Principles

• Describes required functionality in terms of the
  user system
• Identifies external actors
• Identifies system boundary
• Describes scenarios of use
• Describes pre/post conditions
• Describes variants/exceptions

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Use Case Notation (Basic)
System Boundary (often implied)
Use Case
Participates-In Association
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Use Case (Basic) Example
Credit Card System
Perform Card Transaction
Process Customer Bill
Manage Account
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Remember

• Use Case description in format verb direct
  object
• Use Cases are in multiple levels
• Context Level shows most general
• Limit context level use cases to what you would
  put on functionality slide

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Use Cases (Advanced)
Base Use Case
Base Use Case
ltltextendgtgt
Extending Use Case
Common Use Case
Base Use Case
ltltincludegtgt
Included Use Case
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Use Case (Advanced) Example
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Use Case Descriptions

• Sequence of Activities
• Place Order
• 1. Validate User (included)
• 2. Collect users order items
• 3. Set Delivery priority (extend)
• 4. Submit order for processing

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Use Case Descriptions

• Pre and Post Conditions

Preconditions True
Postconditions If customer fails validation
customer exits system If customer
passes validation customer order
processed
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Use Case Descriptions

• Exceptions

• User fails validation
• User cancels order
• User orders invalid item
• User requests invalid quantity
• User order exceeds available credit

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Use Case Hints

• Use language of user
• Avoid implementation
• Get good scenarios
• Names single, identifiable and reasonably atomic
  behavior
• Describes flow of events clearly enough so
  outsider can follow

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Use Case Hints

• Factors common behavior by pulling it from other
  use cases that it includes
• Factors variants by pushes such behavior into
  other use cases that extend it.
• Show only use cases that are important to
  understand system
• Show only actors that relate to use cases

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Use Case Hints

• Specify actor names by specific roles
• Use top level diagram to show context
• Decompose top-level use cases to show
  requirements
• Group common use cases into packages

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Class Exercise Lab 4 Use Cases