Use Cases and Use Case
Diagrams
Reporter:陳雅萍
Outline
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Use cases, actors
Organizing use cases
Modeling the behavior of an element
Use case diagrams
Common modeling techniques
Use Cases and Actors (1)
• A use case
– Specifies the behavior of a system
– Represents a functional requirement of your
system as a whole
– Describes what a system not how it does it
• An actor
– Represents users of use case play when
interacting with use cases
– It’s not part of the system
Use Cases and Actors (2)
Organizing Use Cases (1)
• Organize use case by specifying
– Generalization
– Include
• The base use case pulling behavior from the
supplier use case
– Extend
• Pushing behavior to the base use case
Organizing Use Cases (2)
Modeling the Behavior of an
Element (1)
• Reasons for applying use cases
– A way for domain experts to specify its outside
view to a degree sufficient for developers to
construct its inside view
– A way for developers to approach an element
and understand it
– It served as the basis for testing each element
as it evolves during development
Modeling the Behavior of an
Element (2)
Use Case Diagrams (1)
• Modeling the dynamic aspects of systems
– Use case diagrams are central to modeling
the behavior of a system
• For visualizing, specifying, and documenting the
behavior of an element
– Activity, statechart, sequence and
collaboration diagrams
Use Case Diagrams (2)
• A use case diagram
– A diagram shows a set of use cases and
actors and their relationship
– Contents
• Use cases
• Actors
• Dependency, generalization, and association
relationships
Use Case Diagrams (3)
– Common uses
• Model the context of a system
• Model the requirement of a system
Common modeling techniques (1)
Common modeling techniques (2)
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Use Case and Use Case Diagrams