Use Cases


1. Introduction

Why do we need use cases?

Use cases allow to describe even a complex system in an easy to understand way, and tell in simple terms what the system is going to do for its users. The most difficult aspect of developing a system is  the precise conceptualisation and specification  of the system to be built. Use cases help establish and communicate requirements  of a system in a simple manner.

Use Cases (Formal Definition):

“A description of a set of sequences of actions, including variants, that a system performs that yield an observable result of value to an actor.”

[Rumbaugh, James, Ivar Jacobson, and Grady Booch. “The unified modeling language reference manual.” (1999).]

A use case can be developed as a use case narrative and/or represented diagrammatically using use case diagrams.

Elements of good choice cheap online viagra a use case:

  • Actor: An entity that interacts with the system fot the only now purpose of completing an event. 
  • Functional requirement: Use cases capture functional requirements that specify the intended behaviour of the system.
  • Goals: Use cases are typically initiated by a user to fulfil goals describing the activities and variants involved in attaining the goal.

2. Online Resources

Use case specification:

More formal introduction to use cases: