| 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:
Use Case Diagram Element Toolbox Icons
Icon |
Description |
See also |
|---|---|---|
|
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 |
|
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 |
|
A Test Case is a stereotyped Use Case element which enables you to give greater visibility to tests. |
Test Case |
|
A Collaboration defines a set of cooperating roles and their connectors. |
Collaboration |
|
A Collaboration Use element allows for a Pattern defined by a Collaboration to applied to a specific situation. |
Collaboration Use |
|
A System Boundary element is a non-UML element used to define conceptual boundaries. |
System Boundary |
|
Packages are used to organize your project contents, but when added onto a diagram they can be used to depict the structure and relationships of your model. |
Package |
Use Case Diagram Connector Toolbox Icons
Icon |
Description |
See also |
|---|---|---|
|
A Use relationship indicates that one element requires another to perform some interaction. |
Use |
|
An Association implies that two model elements have a relationship, usually implemented as an instance variable in one or both Classes. |
Association |
|
A Generalization is used to indicate inheritance. |
Generalization |
|
An Include connection indicates that the source element includes the functionality of the target element. |
Include |
|
An Extend connector is used to indicate that an element extends the behavior of another. |
Extend |
|
A Realizes connector represents that the source object implements or Realizes its destination object. |
Realization |
|
An Invokes connector indicates that source object, at some point, causes the destination object to happen. |
Use Case Toolbox |
|
A Precedes connector indicates that the source object must be completed before the destination object can begin. |
Notes
Invokes and Precedes are stereotyped Dependency relationships, defined by the OPEN Modeling Language (OML - Object-oriented Process, Environment and Notation Modeling Language - is an international de facto standard object-oriented development method developed and maintained by the OPEN Consortium). They have been incorporated into the Use Case modeling elements).
- 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