Writing Effective Use Cases

PTR Bullets

Leverage the full power of use cases in real-world software development!

• A practical methodology that makes use cases more accessible than ever before.
• Project standards, formats, style, and detailed "do's and don'ts" for creating use cases that work.
• Based on Cockburn's acclaimed tutorials at OOPSLA and the Software Development Conferences!

PTR Overview

Use cases have never been this easy to understand -- or this easy to create! In Writing Effective Use Cases, Alistair Cockburn offers a hands-on, soup-to-nuts guide to use case development, based on the proven concepts he has refined through years of research, development, and seminar presentations.KEY TOPICS:Cockburn begins by answering the most basic questions facing anyone interested in use cases: "What does a use case look like? When do I write one?" Next, he introduces each key element of use cases: actors, stakeholders, design scope, goal levels, scenarios, and more. Writing Effective Use Cases contains detailed guidelines, formats, and project standards for creating use cases -- as well as a detailed chapter on style, containing specific do's and don'ts. Cockburn shows how use cases fit together with requirements gathering, business processing reengineering, and other key issues facing software professionals. The book includes practice exercises with solutions, as well as a detailed appendix on how to use these techniques with UML.MARKET:For all application developers, object technology practitioners, software system designers, architects, and analysts.

Product Author Bios

Alistair Cockburn is a recognized expert on use cases. He is consulting fellow at Humans and Technology, where he is responsible for helping clients succeed with object-oriented projects. He has more than twenty years of experience leading projects in hardware and software development in insurance, retail, and e-commerce companies and in large organizations such as the Central Bank of Norway and IBM.

Writing use cases as a means of capturing the behavioral requirements of software systems and business processes is a practice that is quickly gaining popularity. Use cases provide a beneficial means of project planning because they clearly show how people will ultimately use the system being designed. On the surface, use cases appear to be a straightforward and simple concept. Faced with the task of writing a set of use cases, however, practitioners must ask: "How exactly am I supposed to write use cases?" Because use cases are essentially prose essays, this question is not easily answered, and as a result, the task can become formidable.

In Writing Effective Use Cases, object technology expert Alistair Cockburn presents an up-to-date, practical guide to use case writing. The author borrows from his extensive experience in this realm, and expands on the classic treatments of use cases to provide software developers with a "nuts-and-bolts" tutorial for writing use cases. The book thoroughly covers introductory, intermediate, and advanced concepts, and is, therefore, appropriate for all knowledge levels. Illustrative writing examples of both good and bad use cases reinforce the author's instructions. In addition, the book contains helpful learning exercises--with answers--to illuminate the most important points.

Highlights of the book include:

• A thorough discussion of the key elements of use cases--actors, stakeholders, design scope, scenarios, and more
• A use case style guide with action steps and suggested formats
• An extensive list of time-saving use case writing tips
• A helpful presentation of use case templates, with commentary on when and where they should be employed
• A proven methodology for taking advantage of use cases

With this book as your guide, you will learn the essential elements of use case writing, improve your use case writing skills, and be well on your way to employing use cases effectively for your next development project.

Customer Reviews

95 of 99 people found the following review helpful Use cases done right - sensible and effective approach, June 30, 2001 By  Mike Tarrani "Jazz Drummer" (Deltona, FL USA) - See all my reviews             Amazon Verified Purchase(What's this?) This review is from: Writing Effective Use Cases (Paperback) Finally! A book that corrects the numerous problems with use cases - or shall I say the mis use of use cases (no pun intended). Here are some common problems that this book will help you to avoid (there are many more, but these spring immediately to mind): PROBLEM: A horde of analysts descend and produce reams of paper that are little more than stick figures and ellipses. They are, well, of little value because they are devoid of any real information and too often confusing. The other side of this problem is an unmanageable number of these "use cases" are produced with inconsistent detail, or an overwhelming amount of detail crammed into a single use case. RESULT: Developers have no clear idea about how to proceed and much rework is done to get the needed information (or developers do proceed and create something not envisioned). PROBLEM: Use cases are considered to be the requirements specification. RESULT: Developers build something based solely on behavior,... Read more Help other customers find the most helpful reviews  Was this review helpful to you?  Report abuse | Permalink  Comment 49 of 49 people found the following review helpful The power of providing real-world examples, May 22, 2001 By  aharnden (North Vancouver, BC Canada) - See all my reviews This review is from: Writing Effective Use Cases (Paperback) If there's one book that can be credited with popularizing use cases, this is it. Alistair Cockburn shares his applied knowledge in `Writing Effective Use Cases' and does so in a very digestible format. This is a handbook, a self-study guide - one full of real-world examples and exercises (with solutions even!) that any analyst or designer can relate to. Use cases are a form of documenting systems requirements and behavioral design specifications. Written well, they offer benefits to all who participate in the development life cycle. This includes analysts, designers, project managers, developers, testers and even end users. Mr. Cockburn's book takes the reader through the writing process, highlighting both good and bad examples. He makes no claims that any of these examples are perfect. And that is perhaps the greatest element of his book. Commit yourself to read through all the examples. By the time you're finished studying them, you will find your own skills in... Read more Help other customers find the most helpful reviews  Was this review helpful to you?  Report abuse | Permalink  Comment 38 of 38 people found the following review helpful Indispensable., October 12, 2001 By  soyaki "a guy" (MI USA) - See all my reviews This review is from: Writing Effective Use Cases (Paperback) This book is filled with both information and examples on how to build use cases to do what they absolutely have to do -- communicate the requirements for software behavior to all involved stakeholders. While Cockburn is perhaps too quick in de-emphasizing most aspects of visual modeling, he is very correct in stating that the model is a small part of the story of the software to be. Happily, Cockburn does not focus much on elicitation techniques (as many other books of its ilk do); frankly, elicitation is probably mostly unteachable and certainly a manner of personal style. Instead, the author focuses on how to distill elicited information into written material that will actually move the project forward. This book probably works very well for a novice. For the more experienced professional, it provides a wealth of ideas to return to. While there are a few bits (the cloud-kite-box indicator scheme comes to mind) that are probably not bound to make an appearance in the average... Read more Help other customers find the most helpful reviews  Was this review helpful to you?  Report abuse | Permalink  Comment

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Praise For Writing Effective Use Cases

"I feel that this is the best book on use cases on the market. I would recommend it strongly to requirements analysts." --Javamug.org, November 2000

Online Sample Chapter

Use Cases: Defining Scope

Preface

More and more people are writing use cases, for behavioral requirements, for software systems or to describe business processes. It all seems easy enough--just write about using the system. But, faced with writing, one suddenly confronts the question, "Exactly what am I supposed to write--how much, how little, what details?" That turns out to be a difficult question to answer. The problem is that writing use cases is fundamentally an exercise in writing prose essays, with all the difficulties in articulating good that comes with prose writing in general. It is hard enough to say what a good use case looks like, but we really want to know something harder: how to write them so they will come out being good.

These pages contain the guidelines I use in my use case writing and in coaching: how a person might think, what he or she might observe, to end up with a better use case and use case set.

I include examples of good and bad use cases, plausible ways of writing differently, and, best of all, the good news that a use case need not be the best to be useful. Even mediocre use cases are useful, more so than are many of the competing requirements files being written. So relax, write something readable, and you will have done your organization a service.

Audience

This book is predominantly aimed at industry professionals who read and study alone, and is therefore organized as a self-study guide. It contains introductory through advanced material: concepts, examples, reminders, and exercises (some with answers, some without).

Writing coaches should find suitable explanations and samples to show their teams. Course designers should be able to build course material around the book, issuing reading assignments as needed. (However, as I include answers to many exercises, they will have to construct their own exam material. :-) )

Organization

The book is organized as a general introduction to use cases followed by a close description of the use case body parts, frequently asked questions, reminders for the busy, and end notes.

The Introduction contains an initial presentation of key notions, to get the discussion rolling: "What does a use case look like?," "When do I write one?," and "What variations are legal?" The brief answer is that they look different depending on when, where, with whom, and why you are writing them. That discussion begins in this early chapter, and continues throughout the book.

Part 1, The Use Case Body Parts, contains chapters for each of the major concepts that need to mastered, and parts of the template that should be written. These include "The Use Case as a Contract for Behavior," "Scope," "Stakeholders and Actors," "Three Named Goal Levels," "Preconditions, Triggers, and Guarantees," "Scenarios and Steps," "Extensions," "Technology and Data Variations," "Linking Use Cases," and "Use Case Formats."

Part 2, Frequently Discussed Topics, addresses particular topics that come up repeatedly: "When Are We Done?," "Scaling Up to Many Use Cases," "CRUD and Parameterized Use Cases," "Business Process Modeling," "The Missing Requirements," "Use Cases in the Overall Process," "Use Case Briefs and eXtreme Programming," and "Mistakes Fixed."

Part 3, Reminders for the Busy, contains a set of reminders for those who have finished reading the book, or already know this material and want to refer back to key ideas. The chapters are organized as "Reminders for Each Use Case," "Reminders for the Use Case Set," and "Reminders for Working on the Use Cases."

There are four appendices: Appendix A discusses "Use Cases in UML" and Appendix B contains "Answers to (Some) Exercises." The book concludes with Appendix C, Glossary; and a list of materials used while writing, Appendix D, Readings.

Heritage of the Ideas

In the late 1960s, Ivar Jacobson invented what later became known as use cases while working on telephony systems at Ericsson. In the late 1980s, he introduced them to the object-oriented programming community, where they were recognized as filling a significant gap in the requirements process. I took Jacobson's course in the early 1990s. While neither he nor his team used my phrases goal and goal failure, it eventually became clear to me that they had been using these notions. In several comparisons, he and I have found no significant contradictions between his and my models. I have slowly extended his model to accommodate recent insights.

I constructed the Actors and Goals conceptual model in 1994 while writing use case guides for the IBM Consulting Group. It explained away much of the mystery of use cases and provided guidance as to how to structure and write them. The Actors and Goals model has circulated informally since 1995 at http://members.aol.com/acockburn and later at www.usecases.org, and finally appeared in the Journal of Object-Oriented Programming in 1997, in an article I authored entitled "Structuring Use Cases with Goals."

From 1994 to 1999, the ideas stayed stable, even though there were a few loose ends in the theory. Finally, while teaching and coaching, I saw why people were having such a hard time with such a simple idea (never mind that I made many of the same mistakes in my first tries!). These insights, plus a few objections to the Actors and Goals model, led to the explanations in this book and to the Stakeholders and Interests model, which is a new idea presented here.

The Unified Modeling Language (UML) has had little impact on these ideas--and vice versa. Gunnar Overgaard, a former colleague of Jacobson's, wrote most of the UML use case material and kept Jacobson's heritage. However, the UML standards group has a strong drawing-tools influence, with the effect that the textual nature of use cases has been lost in the standard. Gunnar Overgaard and Ivar Jacobson discussed my ideas and assured me that most of what I have to say about a use case fits within one of the UML ellipses, and hence neither affects nor is affected by what the UML standard has to say. That means that you can use the ideas in this book quite compatibly with the UML 1.3 use case standard. On the other hand, if you only read the UML standard, which does not discuss the content or writing of a use case, you will not understand what a use case is or how to use it, and you will be led in the dangerous direction of thinking that use cases are a graphical, as opposed to a textual, construction. Since the goal of this book is to show you how to write effective use cases and the standard has little to say in that regard, I have isolated my remarks about UML to Appendix A.

Samples Used

The writing samples in this book were taken from live projects as much as possible, and they may seem slightly imperfect in some instances. I intend to show that they were sufficient to the needs of the project teams that wrote them, and that those imperfections are within the variations and economics permissible in use case writing.

The Addison-Wesley editing crew convinced me to tidy them up more than I originally intended, to emphasize correct appearance over the actual and adequate appearance. I hope you will find it useful to see these examples and recognize the writing that happens on projects. You may apply some of my rules to these samples and find ways to improve them. That sort of thing happens all the time. Since improving one's writing is a never-ending task, I accept the challenge and any criticism.

Use Cases in The Crystal Collection

This is just one in a collection of books, The Crystal Collection for Software Professionals, that highlights lightweight, human-powered software development techniques. Some books discuss a single technique, some discuss a single role on a project, and some discuss team collaboration issues.

Crystal works from two basic principles:

• Software development is a cooperative game of invention and communication. It improves as we develop people's personal skills and increase the team's collaboration effectiveness.
• Different projects have different needs. Systems have different characteristics and are built by teams of differing sizes, with members having differing values and priorities. It is impossible to name one, best way of producing software.

The foundation book for The Crystal Collection, Software Development as a Cooperative Game, elaborates the ideas of software development as a cooperative game, of methodology as a coordination of culture, and of methodology families. That book separates the different aspects of methodologies, techniques and activities, work products and standards. The essence of the discussion, as needed for use cases, appears in this book in Section 1.2, Your Use Case Is Not My Use Case on page 7.

Writing Effective Use Cases is a technique guide, describing the nuts-and-bolts of use case writing. Although you can use the techniques on almost any project, the templates and writing standards must be selected according to each project's needs.

Table of Contents

Preface.


Acknowlegments.


1. Introduction.

PART I. THE USE CASE BODY PARTS.

PART III. REMINDERS FOR THE BUSY.