Requirements Analysis

Requirements analysis results in a model of the system that aims to be correct, complete, consistent, and verifiable. Developers formalize the system specification produced during requirements elicitation and examine in more detail boundary conditions and exceptional cases. Developers correct and clarify the system specification if any errors or ambiguities are found. The client and the user are usually involved in this process, especially when the system specification needs to be changed and additional information gathered. In object-oriented analysis, developers build an analysis model describing the application domain. For example, the analysis model of a watch describes time according to the watch (e.g., Does the watch know about leap years? Does it know about the day of the week? Does it know about the phases of the moon?) The analysis model is then extended to describe how the actors and the system interact to manipulate the application domain (e.g., How does the watch owner resets the time? How does the watch owner resets the day of the week?). Developers use the analysis model, together with nonfunctional requirements, to prepare for the architecture of the system developed during high-level design (see Chapter 6, System Design). In this chapter, we discuss in more detail requirements analysis. We focus on the identification of objects, their behavior, their relationships, their classification, and their organization. We review briefly non object-oriented analysis presentations and methods. Finally, we describe management issues related to requirements analysis in the context of a multi-team development project.