Theory is fine but practice makes perfect. Extreme Programming in Practice is the story of the Object Mentor company's first foray into XP after the Web site it designed and implemented failed. It takes chutzpah to use your own incompetence as a lesson for others.

OK, the "customer" here is internal but the processes the team went through were intended to be identical to those it would use with an external customer. The project was the site-registration system--the part that had failed. There was no question of fixing it, instead the team sat down with its "customer" and started from scratch.

The resulting story as told in Extreme Programming In Practice is fascinating because it's real. By chapter six the authors have already come unstuck through not using automatic testing on code, allowing the "customer" to miss iteration meetings, creating overlong iterations and implementing infrastructure code before the tasks dependent on them. What's especially interesting is that the authors knew what XP said they should be doing yet, for various perceived reasons: internal politics, other work and existing practices among others, chose to do something different.

Almost all these choices caused problems. These ranged from poor time estimates and lots of infrastructure reworking to simply delivering the "wrong" features. Object Mentor learned a lot from its mistakes and if you're about to try XP, you could too, saving a lot of time, money and credibility. --Steve Patient