18 C H A P T E R 3 : U N D E R S T A N D I N G X P
How It Works
XP teams perform nearly every software development activity simultaneously. Analysis, design, coding,
testing, and even deployment occur with rapid frequency.
That??™s a lot to do simultaneously. XP does it by working in iterations: week-long increments of work.
Every week, the team does a bit of release planning, a bit of design, a bit of coding, a bit of testing, and
so forth. They work on stories: very small features, or parts of features, that have customer value. Every
week, the team commits to delivering four to ten stories. Throughout the week, they work on all phases
of development for each story. At the end of the week, they deploy their software for internal review.
(In some cases, they deploy it to actual customers.)
The following sections show how traditional phase-based activities correspond to an XP iteration.
Planning
Every XP team includes several business experts??”the on-site customers??”who are responsible for making
business decisions. The on-site customers point the project in the right direction by clarifying the project
vision, creating stories, constructing a release plan, and managing risks.
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