Requirements Technique: Use Cases and Scenarios

A popular requirements and analysis technique in use today is the development of use cases and scenarios. Use cases are named descriptions of the interaction of an actor (a person or other computer system) within a business process (named business use cases) or with an IT system (named system use cases). System use cases comprise a sequence of steps that outline how the actor achieves a goal using the IT system. For example, “Add Monthly Product Costs” might be a use case with the actor being a sales manager. Scenarios are the detailed variations on the sequence of steps or actions that describe how an actor reaches the goal using the primary and alternative paths. Using our example, we may include a path for adding monthly costs for electronic products, including entering the costs of raw materials and manufacturing, and an alternative path for software products, which has inputs of more detailed labor costs. When a use case is formally defined it can include the following sections: