Presents a streamlined process for developing highly usable software.
　　Desceibes practical methods and models successfully implemented in industry.
　　Complements modern development practices, including the Unified Process and other object-oriented software engineering approaches.

Software for Use is a book for professionals under pressure, for those who work under the dual demands for high-quality software-based systems on the one hand and faster delivery with fewer resources on the other. This book shows how to use streamlined techniques to make software-based systems significantly more usable and useful regardless of whether these systems are installed on desktop computers, ensconced on large mainframe servers, embedded in industrial electronics, or accessed via the World Wide Web. It is written primarily for computer software and applications developers—the analysts, designers, engineers, and programmers who are responsible for producing software systems. In concept, perhaps, usability ought to be the bailiwick of usability specialists. In practice, however, developers of various stripes make the vast majority of the myriad decisions that shape and determine the ultimate usability of software-based products; it is for these frontline troops of the industry that this book was conceived.
　　Usage-centered design, the approach taken in this book, originated with our own frustrating experiences as users of software and our recurring dissatisfaction with software that was unnecessarily awkward and difficult to use. The wealth of established knowledge about human-computer interaction was somehow not being fully translated into more usable products. As we studied how software-based products were being developed, we began to understand where things were going wrong and what needed to be changed in order to deliver better systems.
　　Usage-centered design is a streamlined but systematic approach for devising software closelyfitted to the genuine needs of users—software that is not only more useful and easier to use but also simpler and easier to construct. Usage-centered design is tailored to the high-pressure realities of modern software development. Using a few simple but powerful models, it provides a scheme for quickly understanding users in relation to systems, their working intentions in carrying out tasks, and the support they need from the system to perform those tasks. Its methods and models can be applied within almost any software development life cycle (SDLC) model and incorporated into almost any modern development practices, including various object-oriented (OO) approaches such as the Unified Modeling Language (UML). Usage-centered design is not partial to any one language or platform, being equally effective with rapid iterative development using the latest integrated visual development environments or with character-based control systems running on specialized hardware.
　　A major part of our message to designers and developers of every ilk is simple: Usability is not rocket science. It is often hard work and invariably requires great attention to detail, but, given a few basic conceptual tools, you, too, can learn how to recognize problems in usability and how to improve the usability of the systems you develop. Professor Woody Flowers of the Massachusetts Institute of Technology has given cameras to middle-school students, who then must photograph hard-to-use things and explain the problems. If untrained teenagers can manage the basics of usability, competent adults ought to be able to master the essentials.
　　Quite honestly, we think the model-driven approaches explained in this book can be of value to almost any professional with responsibility for product design and development, and that includes a full range of design specialists, from user interface and interaction designers to ergonomicists and human factors engineers, from graphic artists and industrial designers to human-computer interaction specialists and usability testers. In our experience, the most important prerequisite is not a particular academic degree or level of applied experience, but the willingness and ability to approach the material with an open mind.
　　In our own design work and teaching, our emphasis has always been on simple, powerful techniques that can be quickly learned and applied. For example, a free-lance designer specializing in Web-based applications learned about usage-centered design techniques in a short conference presentation and was able to apply them immediately in her work. After attending a one-hour lecture, a project leader at a computer peripherals company taught his group how to improve the user interfaces of their software through use case models. Around the world are companies successfully applying these techniques to problems as diverse as banking applications, industrial automation controls, and commercial software development tools.
　　We should not give the impression that usage-centered design is for everyone or for all problems. We use models as a kind of vaulting pole, to gain leverage and height in hurdling the problems of user interface design. In our experience, using simple models to understand a problem and potential solutions speeds up the process, but some newcomers to such techniques will find it difficult not to just skip up to the bar and leap before they look.
　　Although we both have backgrounds heavy in the human sciences, we draw a sharp distinction between interesting research issues and the realities of everyday decision making. Among academics and professionals are those who seem to believe that human-machine interaction can be understood only through cognitive and perceptual psychology, that a thorough grounding in the academic literature is a prerequisite for doing effective interaction design. Our own views are that many of the complexities and subtleties that loom so large for researchers and research laboratories are of lesser consequence in everyday decision making.
　　We consider the creative urge a vital force in good design, but we base it on a platform of sound engineering. Some professionals who think of user interfaces as a form of theater or consider design to be based primarily on artistic inspiration have had to struggle with the methodical nature of usage-centered design. On the other hand, the enthusiastic converts to our model-driven approach include designers and artists who have found that abstract models can inspire greater creativity.
　　In organizing the book, we have striven to live up to our subtitle, creating a practical guide that is more than an introduction even if perhaps less than a handbook. To this end, the book is organized into distinct sections. Of course, they are written with the expectation that most readers who want to understand the material thoroughly will take them in sequence. In particular, most of the later chapters depend to a substantial degree on the conceptual foundation laid in the first six chapters. In fact, if all you seek is a general understanding of usage-centered design, Sections I and II cover the core material. In Sections III and IV, we shift to the sundry and sometimes messy details of practical application. This is likely to be of particularly keen interest to developers, especially those with limited background in user interface design, but we would not recommend beginning with these sections.
　　In keeping with the practical, applied focus of the book, numerous small specific examples are used throughout the text. In addition, we have included two completely worked-out applications of usage-centered design. One, introduced in Chapter 4, is used for illustration throughout the middle chapters and concludes in Chapter 10; the other forms the whole of Chapter 15. If you are one of those "get-down-and-dirty" detail-oriented developers who cannot resist seeing how it all works out in the end, you might begin with the applied example in Chapter 15 before going back to build the necessary background by working through Chapters 4 through 14.
　　Because we see on-line documentation to be an integral feature of the user interface and a major factor in usability, we have devoted an entire chapter to help systems. Once familiar with the basics in Chapters 2 and 3 plus Section II, technical writers and documentation specialists should find much of interest in Chapter 11.
　　Professionals who already have a thorough background in human-computer interaction and user interface design and who are most interested in what makes usage-centered design unique may want to skip directly to the core material on the models and modeling techniques in Section II. Other material that has proved to be of particular interest to such professionals can be found in Chapter 12 on the progressive usage model and in Chapter 17 on usability metrics.
　　Managers, project leaders, and others who might be more interested in the management and organizational implications of usage-centered design than in its technical details might start with the first two chapters, then skim Section V on assessment and improvement, and finish off with Section VI on organizing and managing the process.
　　Despite its long gestation period, the material herein is still a work in progress. Just as it has been enhanced and extended through the contributions of our many students and clients, we anticipate it will also be advanced by you, our readers. As we tell every class we have ever taught, we want to hear from you. So, please tell us about your experiences in putting usage-centered design into practice, and we will keep improving on the usability of the process.

This book has been a long time coming. Too long, many would say, and we would have to include ourselves in the chorus. The concepts and techniques of usagecentered design evolved slowly over the entire six years we have been working together. They have flowed from many fonts, emerging from our own work on user interface design problems, from the work of our many clients, from our attempts as teachers to communicate ideas, and from the efforts of our countless students to learn what we were communicating.
　　The book itself has taken about twice as long to write as it should have. We apologize to our clients and students and colleagues who have waited so 1ong, but for all the frustrations there is also compensation: It is a much better book for having had the extra review and input and revision and refinement.
　　Along the way, there have been many contributors, believers, and supporters whom we would like to acknowledge. It began with Ivar Jacobson, who not only contributed a cornerstone of the foundation on which our work is built but also has been a supportive colleague throughout the evolution of our models and methods.
　　It has been said that consulting is a form of paid education. Every good consulting engagement is a leaning experience, and as we have he1ped clients we have also learned from them. Among our many clients have been visionaries who recognized usability as a critical problem in delivering qua1ity service and products and who saw in usage-centered design a practicable solution. It has been our privilege to work with people like Werner Hoefler, Franz Petz, and Helmut Windl of Siemens AG in Germany and Bryan Luke at Westpac Bank in Australia and to help them turn visions into realities.
　　We are gratefu1 to numerous col1eagues who have engaged in a dialogue with us that helped shape and refine our thinking, among them Hugh Beyer, Ian Graham, Karen Holtzblatt, Hermann Kaindl, Meilir Page-Jones, and Rebecca Wirfs-Brock. Special thanks go also to Jared Spool, whose affectionate antagonism has often led us to tighten our concepts and stIeamline our methods.
　　We are particularly grateful to James Noble, who joined with us to teach usagecentered design and brought new energy and insight at a stage when everything seemed settled. In insisting we practice what we preach and calling on us to simplify and generalize, he helped make fundamental improvements in both the approach and how it is taught.
　　We also want to thank Roy Lockwood, who at the age of 87 started learning to use computers and in the process gave us new insights into the shortcomings of modem graphical user interfaces.
　　The book would not be in your hands now were it not for the faith and fortitude of our long-suffering editor, Peter Gordon, who said at the outset that he wanted a work of lasting value, even if it took longer to deliver. We look forward to the long-promised celebratory dinner with him. Our appreciation also goes to associate editor Helen Goldstein and production coordinator Genevieve Rajewski, who alternately cajoled, pestered, and pleaded with us in an effort to bring this work to print. And thanks also to Jean Peck, our vigilant, thorough, and unfailingly correct copy editor, who saved us from numerous small embarrassments and helped polish the final work to an acceptable patina.
　　The greatest debt, not surprisingly, is owed to our students. Those thousands of students in the seminars, workshops, lectures, and tutorials we have taught have also taught us. Every time we teach, we discover something new that causes us to refine the concepts, polish the presentation, and revise our thinking. Thank you, all of you. We will try to keep up with you.

(美)Larry L.Constantine,Lucy A.D.Lockwood：Larry L.Constantine: 是澳大利亚悉尼理工大学计算机科学教授。他是最早从事结构化设计以及现代软件工程理论与实践的许多核心概念和模型研究的专家，是一位国际公认的软件人类因素方面的权威。在近40年的职业生涯中，他共发表了多达130篇论文和文章，出版了10余部专著，其中包括《Software for Use》（获1999年Jolt大奖）。
Lucy A.D.Lockwood: Constantine & Lockwood有限公司总裁，是以使用为中心的设计方法的合作开发者，也是操作概况概念的提出者。作为一位咨询专家、培训教师和撰稿人，她在程序设计和项目管理方面有着15年以上的经历，她侧重于软件可用性以及在软件工程过程中把人与技术进行整合的实用方法的研究。她曾是许多国际会议上最受欢迎的演讲者，在软件开发会议和Web设计与开发会议上担任可用性与用户界面设计分组的主席，还在企业应用开发会议上担任大会主席。她发表的论文涉及用户界面设计、跨功能的团队工作和项目管理等领域。她毕业于塔夫茨大学，曾在悉尼理工大学作访问学者。 Constantine & Lockwood有限公司(http://www.foruse.com)是一个咨询与培训机构，其客户包括世界范围内的一些知名大企业。该公司专门从事针对软件可用性、高绩效团队工作、组织机构文化和变化管理等领域的有关技术与过程的咨询。

Acknowledgments xii
Preface xiv
SECTION I TOWARD MORE USABLE SOFTWARE
1 SOFTWARE FOR USE: Usage, Usability and User Interfaces
Upgrading Usability 3
Approaching Usability 12
Changing Contexts 18
2 BUILT-IN USABILITY: A Usage-Centered Design Approach
Interfacing with Users 21
Elements of a Usage-Centered Approach 23
Driving Models 25
Coordinated Activity 33
3 IN PRINClPLE: Rules and Principles of Usage-Centered Design
Design as Dialogue 41
Rules and Principles 45
Usability Rules 46
User Interface Design Principles 51
Other Rules 63
Details, Details, Details 65
SECTION II ESSENTIAL MODELS FOR USABILITY
4 USERS AND REWED SPECIES: Understanding Users and User Roles
Of Use and Users 69
Real Users and Others 70
User Role Models 78
User Role Maps 84
User Roles in Action 86
Structured Role Models 89
5 WORKING STRUCTURES: Task Modeling with Essential Use Cases
Work, Work, Work 97
Task Modeling 99
The Use Case Map 109
Building Essential Use Case Models 115
Application 119
6 INTERFACE ARCHITECTURE: Interface Contents and Navigation
Workplaces 125
Interface Contents 127
The Context Navigation Map 135
Application 141
SECTION III CREATING THE VISUAL DESIGN
7 OESIGNING THE DIALOGUE: Layout and Communication
From Abstraction to Expression 149
Communication Channels 150
Screen Real Estate 158
8 PRACTICAL WIDGETRY: Choosing and Designing
Visual Components
Buy or Build 165
Iconic Communication 166
Menus 170
Selecting Selection Widgets 179
9 INNOVATIVE INTERFACE: Creative Interface Engineering
and Custom Components
Creative Engineering 185
The Process of Innovation 1B9
Instructive Interfaces 194
Applied Innovation 205
SECTION IV COMPLETING THE OESIGN
10 EXPRESSING SOLUTIONS: Implementation Modeling and rototypes
Fun Stuff 211
Prototypes and Prototyping 212
Mapping the Models 218
Implementation Modeling Illustrated 225
11 HELP ME IF You CAN: Designing Help and Helpful Messages
Even Experts Need a Lift 231
Use Cases for Help 232
Access and Presentation Techniques 237
Special Techniques and Modalities 243
Helpful writing 248
Helpful Messages 253
12 ONCE A BEGINNER: Supporting Evolving Usage Patterns
Beyond Beginners 265
Skiing the Interface 267
Progressive Usage 268
Supportive Interfaces 272
Designing for Progressive Usage 280
Progressive Usage Applied 293
13 IN PLACE: Fitting the Operational Context
Unsound Context 297
Operational Modeling 298
Environmental Adaptation 299
Binding Context 300
Environment Profile 308
Putting Context in Place 313
14 SAME GAME, DIFFERENT FIELDS: Special Applications,
Special lssues
Theme and Variation, Again 317
Web Design for Use 317
Web Wisdom Applied 330
Embedded Systems Applications 338
Other Special Interfaces 354
15 USAGE-CENTERED DESIGN APPLIED: The TeleGuida Case
Scaling Up 357
Telephone Tag 358
Gathering Requirements 359
TeleGuida Users and Uses 366
Toward a TeleGuida Prototype 37B
SECTION V ASSESSMENT AND IMPROVEMENT
16 BETTER NEXT TIME: Improvement by Inspection and Review
Assessing Usability 391
Inspection Methods 399
Collaborative Usability Inspection 401
Focused Inspections 413
17 BY THE NUMBERS: Measuring Usability in Practice
Comparison Shopping 417
Measured Quality 418
User Interface Design Metrics 423
Essential Usability Metrics Suite 426
Metrics in Practice 441
18 TEST SCORES: Laboratory and Field Testing of Usability
History Testing 443
Testing, One, Two 444
Test Protocol 450
Testing Tactics 456
Why Test, Why Not 460
SECTION VI ORGANIZING AND MANAGING THE PROCESS
19 CODE AND YOU'RE DONE: Implementing Interfaces
Objects and Interfaces 465
Accelerated Development 472
Visual Development of Visual Designs 475
20 Using YOUR USERS: Users in the Development Process
Use or Abuse of Users 481
Requirements Dialogue, Requirements Dance 485
Going to the Source 489
Using Users 494
Joint Essential Modeling 499
21 GETTING ORGANIZED: Usability in the Larger Context
Organiational Units 511
Standards and Style Guides 513
Competing Constituencies 517
Experts and Expertise 522
Cultural Fit 524
Appendix A: Suggested Readings 533
Appendix B: Eleven Ways to Make Software More Usable:
General Principles of Software Usability 535
Appendix C: Glossary 537
Appendix D: Forms for Usage-Centered Design 545
Appendix E: Subjective Usability Scales for Software (SUSS)
References 551
Index 561