Chapter 1: Question #18: What is a use case?
Use cases are simple descriptions of a system’s functions from the bird’s-eye view of the users. Use case diagrams are functional diagrams in that they portray the basic functions of the system – that is, what the users can do and how the system should respond to the user’s actions. Use cases are the primary drivers for all the UML diagramming techniques. A use case communicates at a high level what the system needs to do, and all the UML diagramming techniques build on this by presenting the use-case functionality in a different way for a different purpose. Use cases are the building blocks by which the system is deigned and built. (Dennis, 2009)
Chapter 1: Question #19: What is meant by use-case driven?
Use –case driven means that the use cases are the primary modeling tools defining the behavior of the system. A use case describes how the user interacts with the system to perform some activity, such as placing an order, making a reservation, or searching for information. The cases are used to identify and to communicate the requirements for the system to the programmers who must write the system. Use cases focus on only one activity at a time. In contrast, the process model diagrams used by traditional structured and RAD methodologies are far more complex because they require the system analyst and user to develop models of the entire system. Use cases focus on only one activity at a time, so developing models is much simpler. (Dennis, 2009)
References:
Dennis, A. Wixom, B., Tegarden, D. (2009). System Analysis & Design with UML Version 2.0:
An Object-Oriented Approach/3e. (pgs. 18 and 166-167). Hoboken: John Wiley & Sons.