Extreme Programming Refactored: The Case Against XP

Mixing humor with serious discussion is risky, but the authors have succeeded. Their criticisms of a fad methodology are fair and needed.

Barry Boehm once published a landmark paper on software defects, relating when you find them to how much they cost to fix. He found that defects were cheaper to fix the earlier in the development process you found them, which should surprise no one-adding or removing a sentence in a requirements document beats the heck out of screwing up everyone's paychecks in a production system. But the interesting part was how much cheaper it was to change a program in analysis than in production-orders of magnitude cheaper. Boehm's data produced a very steep cost curve as the project moved from design to implementation and out to the field-the most expensive place of all.So, years later, along comes a methodology called XP and claims to flatten the Boehm curve. The cost of change is now constant across the whole lifecycle, say the XP evangelists. It doesn't matter if we miss requirements up-front, or if we have to redesign the code over and over. Heck, it doesn't matter if you change your mind about the very nature of the system halfway through development. We're agile. Change is free.And how does XP work this miracle? XP's big idea is to scrap the analysis and design phases altogether, and get the code into maintenance as fast as humanly possible. In other words, XP flattens the Boehm curve by throwing out the cheapest segments of the curve, and spending the entire project in the most expensive segment. If that makes your ears prick up a little, you're not alone. The authors of this book had the same reaction back in the late nineties, when the XP hype wave was just beginning. They've examined XP thoroughly and critically, picked out the good ideas, skewered the fallacies, and documented the history of evangelical hype that characterizes XP. If you, your management, or your co-workers are tempted by the siren song of XP, you need this book.The flagship XP effort, the Chrysler C3 payroll system, was a Y2K project that was cancelled in early 2000, after taking four years to deliver a third of the required functionality. Pro-XP books still moon and coo over this "greatest development project in the world," even though it was, in the end, an abject failure. You will get the true history of C3 in this book, and the best analysis of why it failed (C3 was a straightforward replacement of a functioning and satisfactory legacy system. Why do you need an "agile" process to understand that? Why would you sneer at systems analysis when the existing systems provide, by definition, a full specification of what you have to achieve?). If you've been reading about the "revolution" in software development at Chrysler, you need this book.Last of all, if you've been hearing about the benefits of XP practices like unit testing, pair programming, and so forth, you truly need this book. The title is "Extreme Programming Refactored," not just "Extreme Programming Denounced," and a very important part of the book consists of the authors picking out what they see

Remarkably little has been published that is critical of extreme programming. "Questioning Extreme Programming" (McBreen) doesn't ask the really tough questions. Boehm and Turner's recent "Balancing Agility and Discipline" is a more even-handed exploration of agile practices--especially XP, but it's too polite and doesn't draw out the full implications of its arguments. XP Refactored is the first book to seriously and deeply critique extreme programming. The authors poke fun at the excesses of extreme programming, of which, by the definition of "extreme," there are many. The book contains the best critique of the legendary Chrysler C3 project I've seen, including a good discussion about why it really is more myth than legend. The authors do a good job of countering Beck's claim that "turning the dial up to 10" is a good idea. Although it isn't the most enjoyable part of the book, the most technically interesting part of the book is the chapter on "Extreme Programming Refactored." The authors see a lot of value in the specific practices of XP; they'd just like to turn the dial down from 10 on some of the practices, reorganize others, and tone down some of the religion. For the past couple years, some XP advocates have been advocating extreme programming with a fervor normally associated with deeply held religious beliefs -- attacking whenever their belief system is questioned. Historically, humor has been a good response to religious overzealousness, and this book is hilarious. It compares XP to a ring of poisonous snakes, a failed barbecue, and many other vivid analogies. Ultimately, this book is a polarizing book, much like XP itself. People who love XP will hate this book. People who hate XP will love this book. People who are open minded about XP will enjoy the book and get a better understanding of XP's minuses -- as well as its pluses -- at the same time.

I liked this book, because it dares to point out the dangers in having blind faith in XP, something that seems to be a requisite in order to be truly doing XP.It is not totally against XP, detailing some of the areas in which the author thinks XP has something to add to software engineering, but helps uncover the many bizarre, contradictory, or simply untrue statements made in the XP world. In fact it is quite easy to see that with this book in hand you have a cynical, wise cracking guide, that can actually make your XP projects safer and less prone to extremes, so to speak.It does all this with lashings of humour. If you don't like humour in a computer book, go elsewhere. If you love XP and believe all unbelievers are scared, in denial, blind, then you won't like the humour either. If, like Ron Jeffries, a lot of the book is about you, you most certainly won't like the book.I'm quoted in the book myself, so can't claim to be a neutral observer. But there again, no one really is, we all have a viewpoint, and it colours all we do and say.If you do XP or are thinking of doing XP, buy this book. It is an antidote to all the hype and rah rah found in the many many XP books out there. Alrady there has been talk about how to "stop this book". Enough said.

I'm a pro-XPer, but I was surprised how much I enjoyed reading this book. That's because it provides a well balanced critique, and suggests good alternatives. And the satire is right on the nose. But (probably because of that) it's bound to anger some people.You shouldn't be put off by negative comments from the people that the book is criticizing. They're the same people that think solo coders are genetic defects (see the recent article in Wired magazine).Buy this book and read it for what it is - an independent critique of extreme programming. Highly enjoyable!