Extend Post
Download as PPT, PDF0 likes254 views
This document discusses when and how to extend use case diagrams. It recommends extending use cases when steps or branching activities are duplicated across use cases or are too complex. An extend relationship connects an extension use case to a base use case at extension points. The extension is conditional on events in the base use case. Extensions can make optional behavior explicit or show behavior under exceptional conditions.
Extend Post
- 1. Relating Multiple USE CASES Use case Way of using the system
- 2. When to extend the Use Case Diagram? Write major steps or branching activities of a Use Cases as separate use cases when: They are duplicated in other Use Cases. They are complex and long, and separating them helps factor the use cases into manageable comprehensible units.
- 3. UseCase Diagram with Extend & Include Relationship
- 4. Extends Relationship: The extend-relationship connects an extension use case to a base use case. You define where in the base to insert the extension by referring to extension points in the base use case. The extension is conditional, which means its execution is dependent on what has happened while executing the base use case. The base use case does not control the conditions for the execution of the extension – the conditions are described within the extend-relationship
- 5. We can use the extensions for several purposes: To show that a part of a use case is optional, or potentially optional, system behavior. In this way, you separate optional behavior from mandatory behavior in your model. To show that a subflow is executed only under certain (sometimes exceptional) conditions, such as triggering an alarm. To show that there may be a set of behavior segments of which one or several may be inserted at an extension point in a base use case. The behavior segments that are inserted (and the order in which they are inserted) will depend on the interaction with the actors during the execution of the base use case.