Prev Next

Use Case Diagram

Use Case diagrams capture Use Cases and the relationships between Actors and the subject (system). You can use them to:

  • Describe the functional requirements of the system
  • Describe the manner in which outside things (Actors) interact at the system boundary
  • Describe the response of the system

You generate Use Case diagram elements and connectors from the 'Use Case' pages of the Diagram Toolbox.

Example Diagram

This diagram illustrates some features of Use Case diagrams:

UML Use Case diagram example in Sparx Systems Enterprise Architect.

Use Case Diagram Element Toolbox Icons

Icon

Description

See also

Actor element

An Actor is a user of the system; user can mean a human user, a machine, or even another system or subsystem in the model.

Actor
Use Case element

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.

Use Case
Test Case element

A Test Case is a stereotyped Use Case element which enables you to give greater visibility to tests.

Test Case
Collaboration element

A Collaboration defines a set of cooperating roles and their connectors.

Collaboration
Collaboration Use element

A Collaboration Use element allows for a Pattern defined by a Collaboration to applied to a specific situation.

Collaboration Use
Boundary element

A System Boundary element is a non-UML element used to define conceptual boundaries.

Boundary
Package element

Packages are used to organize your project contents, but when added onto a diagram they can be use for structural or relational depictions.

Package

Use Case Diagram Connector Toolbox Icons

Icon

Description

See also

Use connector

A Use relationship indicates that one element requires another to perform some interaction.

Use
Association connector

An Association implies that two model elements have a relationship, usually implemented as an instance variable in one or both Classes.

Associate
Generalization connector

A Generalization is used to indicate inheritance.

Generalize
Include connector

An Include connection indicates that the source element includes the functionality of the target element.

Include
Extend connector

An Extend connector is used to indicate that an element extends the behavior of another.

Extend
Realization connector

A Realizes connector represents that the source object implements or Realizes its destination object.

Realize

An Invokes connector indicates that source object, at some point, causes the destination object to happen.

Use Case Group

A Precedes connector indicates that the source object must be completed before the destination object can begin.

Notes

  • Invokes and Precedes relationships are defined by the Open Modeling Language (OML); they are stereotyped Dependency relationships
  • Invokes indicates that Use Case A, at some point, causes Use Case B to happen
  • Precedes indicates that Use Case C must complete before Use Case D can begin

Learn more