Creating Use Cases or Extension Points

A use case depicts a closed set of actions that describe a certain behavior a system carries out step-by-step. You use extension points to depict flow time points when a behavior is extended by other use cases.

Creating a Use Case

Context

A use case is closed sequence of worksteps within a system that describes a certain behavior a system carries out. A use case forms a kind of wrapper for worksteps and can also include special cases It is initiated by an actor and they are then communicated with using one of the following messages .

The use case represents the view of the actor.

You cannot drag a use case system over a set of use cases at a later stage. For this reason, you should start with the use case system and assign use cases to it.

How to proceed

  1. Position the mouse pointer where you want in the diagram.

  2. Click the right mouse button and click on the use case icon in the context menu's mini toolbar.

    The use case is created and is given a default name. You can immediately change this.

Alternatively, it is also possible to create a use case via an existing actor's carousel with an association.

Creating an Extension Point for an Extended Use Case

Context

You can extend a use case. You can define extension points in the extended use case (target of a corresponding extend dependency) and show at which point in time an extension takes place in the flow, e.g. use of the respective behavior of the extending use case (source). It is also possible to add an text to the extension point's name to describe the extension point (the point in time) in the flow in more detail.

It is possible to configure that the use case is shown as owner for extension points in the Details tool window

If the extension is conditional, then refer to this extension point in the condition for an extend dependency.

How to proceed

  1. Click in the diagram with the right mouse button on the (extended) use case you want to create an extension point for.

    The context menu and mini toolbar appear.

  2. Select the extension point icon in the mini toolbar.

    The extension point is created in the use case. A default name is created and selected.

  3. Enter a unique name for the extension point in the use case and a detailed description of the extension point by double clicking on it, if required. Then press the [Enter] key.

    The name and the description (if applicable) are shown in the use case. The use case is enlarged if necessary.

    An error message appears if the name entered is not unique.