The Unified Modeling Language User Guide SECOND EDITION [Electronic resources] نسخه متنی

Chapter 18. Use Case Diagrams

In this chapter

• Modeling the context of a system

• Modeling the requirements of a system

• Forward and reverse engineering

Use case diagrams are one of the diagrams in the UML for modeling the dynamic aspects of systems. (Activity diagrams, state diagrams, sequence diagrams, and communication diagrams are four other kinds of diagrams in the UML for modeling the dynamic aspects of systems.) Use case diagrams are central to modeling the behavior of a system, a subsystem, or a class. Each one shows a set of use cases and actors and their relationships.

You apply use case diagrams to model the use case view of a system. For the most part, this involves modeling the context of a system, subsystem, or class, or modeling the requirements of the behavior of these elements.

Use case diagrams are important for visualizing, specifying, and documenting the behavior of an element. They make systems, subsystems, and classes approachable and understandable by presenting an outside view of how those elements may be used in context. Use case diagrams are also important for testing executable systems through forward engineering and for comprehending executable systems through reverse engineering.