In the quest for quality, software developers have long focused on improving the internal architecture of their products. Larry L. Constantine--who originally created structured design to effect such improvement--now joins with well-known consultant Lucy A. D. Lockwood to turn the focus of software development to the external architecture. In this book, they present the models and methods of a revolutionary approach to software that will help programmers deliver more usable software--software that will enable users to accomplish their tasks with greater ease and efficiency. Recognizing usability as the key to successful software, Constantine and Lockwood provide concrete tools and techniques that programmers can employ to meet that end. Much more than just another set of rules for good user-interface design, this book guides readers through a systematic software development process. This process, called usage-centered design, weaves together two major threads in software development methods: use cases (also used with UML) and essential modeling. With numerous examples and case studies of both conventional and specialized software applications, the authors illustrate what has been shown in practice to work and what has proved to be of greatest practical value. Highlights Presents a streamlined process for developing highly usable software Describes practical methods and models successfully implemented in industry Complements modern development practices, including the Unified Process and other object-oriented software engineering approaches