Use Cases and Use Case Diagrams

Reporter:陳雅萍

Outline

• 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 th

e behavior of a system• For visualizing, specifying, and documenting the b

ehavior of an element– Activity, statechart, sequence and collaboratio

n diagrams

Use Case Diagrams (2)

• A use case diagram– A diagram shows a set of use cases and actor

s and their relationship– Contents

• Use cases• Actors• Dependency, generalization, and association relati

onships

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)