Use Case

Description

A Use Case is a UML modeling element that describes how a user of the proposed system interacts with the system to perform a discrete unit of work. It describes and signifies a single interaction over time that has meaning for the end user (person, machine or other system), and is required to leave the system in a complete state: the interaction either completed or rolled back to the initial state. A Use Case:

• Typically has requirements and constraints that describe the essential features and rules under which it operates
• Can have an associated Sequence diagram illustrating behavior over time; who does what to whom, and when
• Typically has scenarios associated with it that describe the workflow over time that produces the end result; alternative workflows (for example, to capture exceptions) are also enabled

Example Use Case diagram

If extending a Use Case, you can specify the points of extension with Use Case Extension Points. To display the attributes, operations or constraints of a Use Case on a diagram, use Rectangle Notation.

Enterprise Architect also provides two stereotyped Use Cases: the Test Case and the Business Use Case.

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Learn more

• Sequence Diagram
• Use Case Extension Points
• Rectangle Notation
• Test Case
• Business Modeling/Interaction

OMG UML Specification:

The OMG Unified Modeling Language specification, (v2.5.1, p.649) states:

A UseCase specifies a set of actions performed by its subjects, which yields an observable result that is of value for one or more Actors or other stakeholders of each subject.