TABLE OF CONTENTS This chapter provides an introduction to the requirements discipline of the Unified Process. It is based heavily upon the use case analysis that originated in the Objectory design method (Jacobson et al., 1992). Subsequent chapters discuss the analysis and design as well as implementation disciplines of the Unified Process.
The remainder of this chapter introduces the use case analysis process, the notation used to represent use cases and the steps performed to generate a use case. A worked example is presented at the end of the chapter.
The requirements discipline attempts to express the systems requirements in terms of use cases. Thus the output of this discipline is a Use Case model. A Use Case model comprises a set of:
use cases describing particular interactions with the system
actors who interact with the system
other artefacts including GUI prototypes and non-functional requirements
Use cases attempt to capture the functional requirements of the system by describing the different ways in which an actor (essentially a type of user) can interact with the system. The intention is that the focus should be on the value added to each type of user by a use case. If a use case does not add value, then it is not required.
Use cases are very important from the point of view of the Unified Process, as they are the key drivers of the whole process. That is, not only do the use cases help to identify what the...
