Use Case

• A use case specifies the behavior of a system or a part of a system and is a description of a set of sequences of actions, including variants, that a system performs to yield an observable result of value to an actor.

Use case

• Actors: can be human or automated systems

• A use case describes what a system does but it does not specify how it does it.

Sample Use Case 1.

Use Case Name Login

Description User logs into the HACS system

Actor Can be cell phone User, laptop User, and PDA User, etc.

Precondition The system is on

Basic flow of events

1. The system prompts the User enters username and password

2. The User enters username and password

3. The system validates the entered username and password

4. The system logs the User into the system

Alternative flow of events

If the User enters an invalid username and password pair, the use case restarts

Postcondition User enters correct username and password

Special requirements

Interface exists to allow connection between the User’s remote device and the system

Reference

• Class note: Module 14

• Textbook: The Unified Modeling Language User Guide, chapter 16, page 223-224