UseCase Diagrams in Astah represent system functions and interactions between external actors and the system.

UML_UseCase_Diagram_With_Icons
UML UseCase Diagram Sample
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Creating an Actor

Actors in UML UseCase Diagram

  1. Select [Actor] from the tool palette.
  2. Choose from Normal Actor or Business Actor (not supported in Astah SysML or Astah System Safety).
    Actors on tool palette

  3. Click on the diagram to place it.
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Creating a UseCase

UseCase

  • Double-click anywhere on the diagram or select UseCase from the tool palette.
  • Choose from Normal UseCase or Business UseCase (not supported in Astah SysML or Astah System Safety).
    UseCase and Business UseCase
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Adding Extension Points

UseCase Extension Points
  1. Right-click a UseCase and select [Add Extension Point].
    Extension Point

  2. The Extension Point appears below the UseCase name.
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Show UseCase name outside

UseCase name location

Right-click a UseCase and choose [Name in Oval] to toggle the name display position.
UseCase Name location

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Extend / Include Relationships

Sample Extend and Include between UseCases

You can create Extend and Include relationships using the suggest feature:

  1. Hover over a UseCase until a mini icon appears.
  2. Choose [E] for Extend or [I] for Include and drag to the target UseCase.
    Extend - Include - UseCaseCreating an extend between UseCases

Important:
Dependencies with the stereotypes «extend» or «include» are not recognized as true UML relationships by Astah.

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UseCase Description

You can create a UseCase Description for each UseCase.

UseCase Description

Note:
UseCase Descriptions are not supported in Astah System Safety or Astah SysML.

Open / Create a UseCase Description

  • Right-click a UseCase → [Open UseCase Description]

Open UseCase Description

Switch Templates

Astah provides three pre-installed templates:

  1. Astah Original (Default)
  2. Complete Format by Alistair Cockburn
  3. RUP Style

Go to [Tools] → [Template Settings] → [UseCase Description] to switch between templates.

Switch Template

UseCase Template Switch

Create a Custom Template

  1. Go to [Tools] → [Template Settings] → [UseCase Description]
  2. Click [New], customize the template, and click [OK]
    Create a new template for UseCase Description

  3. The customized template is saved as UCDescriptionProp.properties in your user directory
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Drawing a System Boundary

A System Boundary visually defines the scope of the system being modeled.
To draw it:

  1. Select the Rectangle tool from the tool palette.
    Rectangle in Astah

  2. Draw a rectangle that encloses the UseCases belonging to the system.
  3. Optionally, label the boundary with the system name using the text tool from the tool palette.
    System Boundary in UseCase Diagram

or you can use the Subsystem model from the tool palette and use it instead of the rectangle.

Using Subsystem for System Boundary in UseCase Diagram in Astah.

Sample Image Reference: Figure 18.2 Class diagram of a Package owning a set of UseCases, Actors, and a Subsystem from Unified Modeling Language 2.5.1