Addressing the essential difficulties of software engineering

The central concept of Brooks' classic paper, “No Silver Bullet,” is that the hard part of building software is the specification, design, and testing of the conceptual construct that comprises the essence of software. The purpose of this article is fourfold: (1) to develop a formal conceptual framework for representing all aspects of a client organization, including those that have traditionally not been addressed formally, such as “culture,” “values,” “concepts,” and perspective; (2) to use this framework to gain a more detailed understanding of Brooks' essential difficulty, including a better understanding of the sources of conceptual errors, particularly in the requirements definition phase; (3) to show that Brooks' essential difficulty is inextricably involved with a second essential difficulty, namely, that the computer system is built by one group of people, for another group of people, who differ from them in at least one, usually very important, way, including their work activities, language, the fundamental concpets that define their work and what it is about, and the principles that form the basis for their choices in their work; and (4) to present Outside-In Development, a methodology for addressing these intertwined essential difficulties.