Mike Cohn - User Stories Applied

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T HE A DDISON -W ESLEY S IGNATURE S ERIES

S IGNERS: K ENT B ECK & M ARTIN F OWLER

Martin Fowler has been a pioneer of object technology in enterprise applications. His central concern is how to design software well. He focuses on getting to the heart of how to build enterprise software that will last well into the future. He is interested in looking behind the specifics of technologies to the patterns, practices, and principles that last for many years; these books should be usable a decade from now. Martins criterion is that these are books he wished he could write.

Kent Beck has pioneered people-oriented technologies like JUnit, Extreme Programming, and patterns for software development. Kent is interested in helping teams do well by doing good finding a style of software development that simultaneously satisfies economic, aesthetic, emotional, and practical constraints. His books focus on touching the lives of the creators and users of software.

T ITLES IN THE S ERIES

Implementation Patterns
Kent Beck, ISBN 0321413091

Test-Driven Development: By Example
Kent Beck, ISBN: 0321146530

User Stories Applied: For Agile Software Development
Mike Cohn, ISBN: 0321205685

Implementing Lean Software Development: From Concept to Cash
Mary and Tom Poppendieck, ISBN 0321437381

Refactoring Databases: Evolutionary Database Design
Scott W. Ambler and Pramodkumar J. Sadalage, ISBN 0321293533

Continuous Integration: Improving Software Quality and Reducing Risk
Paul M. Duvall, with Steve Matyas and Andrew Glover, 0321336380

Patterns of Enterprise Application Architecture
Martin Fowler, ISBN: 0321127420

Refactoring HTML: Improving the Design of Existing Web Applications
Elliotte Rusty Harold, ISBN 0321503635

Beyond Software Architecture: Creating and Sustaining Winning Solutions
Luke Hohmann, ISBN: 0201775948

Enterprise Integration Patterns: Desinging, Building, and Deploying Messaging Solutions
Gregor Hohpe and Bobby Woolf, ISBN: 0321200683

Refactoring to Patterns
Joshua Kerievsky, ISBN 0321213351

Mike Cohn

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13th printing, February 2009

To Laura, for reading this one;
To Savannah, for loving to read;
To Delaney, for insisting you already know how to read.
With readers like you, its easy to write.

How do you decide what a software system is supposed to do? And then, how do you communicate that decision between the various people affected? This book takes on this complicated problem. The problem is difficult because each participant has different needs. Project managers want to track progress. Programmers want to implement the system. Product managers want flexibility. Testers want to measure. Users want a useful system. Creating productive conflict between these perspectives, coming to a single collective decision everyone can support, and maintaining that balance for months or years are all difficult problems.

The solution Mike Cohn explores in this book, User Stories Applied , is superficially the same as previous attempts to solve this problemrequirements, use cases, and scenarios. Whats so complicated? You write down what you want to do and then you do it. The proliferation of solutions suggests that the problem is not as simple as it appears. The variation comes down to what you write down and when.

User stories start the process by writing down just two pieces of information: each goal to be satisfied by the system and the rough cost of satisfying that goal. This takes just a few sentences and gives you information other approaches dont. Using the principle of the last responsible moment, the team defers writing down most details of the features until just before implementation.

This simple time shift has two major effects. First, the team can easily begin implementing the juiciest features early in the development cycle while the other features are still vague. The automated tests specifying the details of each feature ensure that early features continue to run as specified as you add new features. Second, putting a price on features early encourages prioritizing from the beginning instead of a panicked abortion of scope at the end in order to meet a delivery date.

Mikes experience with user stories makes this a book full of practical advice for making user stories work for your development team. I wish you clear, confident development.

Kent Beck