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Extreme Programming Refactored
The Previous Extreme - What XP Set out to Fix It had previously been accepted practice to spend months (years, even, on large-scale projects) gathering requirements, then another year or two on design, before a single line of production code had been written. The infamous "big bang delivery" occurred when this gigantic monolith of a software system was finally delivered to the customer, only for the customer to retort that this was nothing like what he wanted.
It was also accepted practice to divide the system into separate subsystems, and attempt to integrate them after several months. By this time, each subsystem would have taken on a life of its own, and integrating these disparate monoliths together gave a whole new meaning to "plug and pray."
How XP "Fixes" It XP takes the development process to the other extreme, by shortening the "waterfall" lifecycle to weeks, days, even minutes. In fact, Kent Beck describes XP as a "waterfall run through a blender." Iterations typically last for a week or two; there is a high emphasis on code quality via unit testing; and code is integrated "constantly" so that it never becomes out of synch with the rest of the project. Beck is often quoted for saying that the XP practices "turn the dial all the way up to 10" -- that is, if something is good (testing, integrating, pair programming etc), well then, let's do it all the time.
There's a lot to be gained from learning about XP, and agile practices in general. However, many feel that XP has taken things too far. By taking things to the opposite extreme, we're just introducing a fresh set of problems. The optimum solution, then, must lie somewhere between these two extremes. That is fundamentally what Extreme Programming Refactored (XPR) is about.
Optimizing the Process There's been a lot of controversy surrounding this book. It grew out of an equally controversial article that appeared on the author's website. XP advocates were arguing on Yahoo! Groups over XPR's good and bad points, miraculously, months before the book was even available. XP zealots were even posting messages telling others not to buy the book, before they'd even had a chance to read it for themselves and find out what it's all about.It's important to note that XPR isn't the anti-XP slam piece that some people had been expecting. It does rip into the XP practices in plenty of detail, but importantly it also describes alternatives, and talks about the good aspects of XP.
The authors make the argument that "turning the dial up to 10" mostly isn't such a good thing, and that to achieve our "holy grail" development process, we just need to turn the dial down a little bit -- let the milk simmer rather than boil over. We can do this by adding in some additional practices that take the burden off the overloaded, heavily interdependent XP practices.
For example, not everyone likes to pair program (with two people sitting at one computer). It just isn't for everyone. However, XP relies on everybody in the team pairing all the time. So if you don't like to "pair up," what choice do you have but to leave the project? XPR adjusts the other practices, placing a bigger emphasis on up-front design and documentation, so that pairing up doesn't have to be mandatory.
XPR also argues that it is possible to achieve a decent design before writing the code. The authors don't want a return to "BDUF" (Big Design Up Front), but instead to achieve an ideal middle-ground. The result is more akin to the monthly Sprints found in Scrum (www.controlchaos.com).
Similarly, XPR argues that the customer (and users) usually do have a pretty good idea what they want from a new system, and that they don't have to see a live system first before realizing that they wanted something entirely different. The authors argue in favour of interaction design as a way of achieving this goal.
XPR achieves all of this with more than a mild dose of satire. It's important to realize this -- the book is essentially "taking the piss" out of the more extreme XP practices, and the quasi-religious Extremo culture that has quickly grown up around XP. It has lots of serious things to say, but has a slight danger of that being lost "in the chuckles." There again, the danger is less to do with the book, and more to do with the reader.
XP sealots will never be swayed by such a book, naturally, but they are not the audience. It is for those undecided, or the cowed XP skeptics who know something is very wrong at the heart of the beast, but haven't have the words to say it. Even for zealots, I'd hope they'd put the hatred for long enough to at least temper their XP actions, to turn the dial down a little, to read the contents with the possibility in their minds that XP isn't the final perfect expression of all programming methodologies. Just for a while...
If you are scared of the contents, a favorite XP accusation, then of course you'll point out the 'needless humour,' blah blah, anything rther than address what the book says. Form will be far more addressable than content. It's the old "ignore this man, he wears a colourful tie" excuse, pick on some small detail that you feel is a weakness and totally ignore all the embarrassing questions you'd rather not address. If you like the contents, then the humour will be seen as a playful, court-jester like addition to what is a seriously analytical book
In conclusion, this book is well written, thought provoking, and above all entertaining (an aspect which seems to be proving almost heretical among some XP advocates). I found this to be a fun read, unlike some books, it was never a chore. It's extremely conversational, like having a cynical, wise-cracking guide. It's a pity more computer books aren't this fun. A spoonful of sugar and all that...
In fact this book is pretty damn wonderful. I know, it may sound a bit gushing, but before you review my review, give the book a read yourself. It's a thing of beauty, a rare mix of positive and negative, sweet and sour, opinion, and XP's favorite emotion, courage, courage enough to say "the emperor has no clothes." I can't see how you could read this book from beginning to end and not see XP in a different light.
In fact, XP programmers would do well to read this book, as it presents the negative path, something other than sunny-day scenarios. Using these warnings and guidelines, they'd have much more successful projects, as this book points out the dangers of lack of XP discipline, fragility and so on.
The truth is that I couldn't do justice to this book in such a short review. There is just so much evidence, so many contradictions pointed out, endless damning words from XPer's own mouths. It was supposed to be a small book to start of with, 150 pages or so, but due to the sheer body of evidence and submitted real life stories from those in the trenches, it bloomed to 400+ pages.
As Doug Rosenberg says "I don't want to be nearby when somebody decides to deploy an air traffic control system or some missile-targeting software that has been developed with no written requirements, and where the programmers made the design up as they went along." At least don't say you weren't warned!
You can purchase Extreme Programming Refactored: The Case Against XP from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
The XP guys _have_ made a mark in the world. Now, how that is going to work out longer term, remains to be seen. XP _is_ influecing stuff like IBM's Rational Unified Process.
I tend to like XP. I haven't worked in an XP shop, but I have used it in class projects and some project of my own.
Right now, lots shops have processes that are non-existant or chaotic--that is what XP really needs to be compared against. XP isn't "the emperor" more like an upstart prince edging in on the territory of being eyed(but not governed) by Emperor RUP.
My gut is that was is motivating books like this:
is the fact that XP is being adopted in places where stuff like RUP just would never get a toe in the door in its present state.
The major stages of the opponents of an invention:
a) it won't work
b) its evil
c) its not really new
d) we invented it
This stuff strikes me as somewhere between stage a-b.
I would have like to have seen less of the pre-emptive rebuttal and more reviews on some of the findings and recommendations.
Drop the dogma and theology, and give us the hard core, nitty-gritty, down and dirty facts.
I cannot attest to actually having been involved in any project which used XP as defined but I can say the following about what I consider similar:
I used to work at a company that strangely enough fostered both getting things done quickly for some projects while fostering a long drawn out method for other projects.
The company was a consulting firm which always needed an answer yesterday for this or that problem.
They also wrote fairly large simulation packages for the FAA. Some of these projects would go up to three years. Lots of planning etc. was usually done.
Regardless of which type project I worked on I always tended to be the type who would get something working quick and then iterate over it several times if necessary.
Others tended to be going at what I considered to be a snails pace mode. They would plan for days, weeks, months on something that I never considered worth that much planning.
I could usually have a pretty good prototype working with a couple of major revisions made before the "planning types" could even get out a initial prototype.
But, over the years I noticed that I (and those like me) tended to get "officially finished" in about the same amount of time that the annoying guys who planned everything out to the Nth degree got finished.
Was my product any better than their's? No not really.
Which methodology was better? It's hard to say, I know I certainly always liked to utilize new methodologies that worked well while they liked to stick with the tried and true.
About the only thing that I can say is that my internal company clients usually appreciated that they had something to work with earlier rather than later.
They knew it was a rough version, but hey, if you need it now, you need it now. And two years from now may not pay the bills.
So, lots of times I came out looking like a hero.
But, looking back on it now I'd have to say that my own personal version of XP wasn't any better than my counterpart's long drawn out process, at least in terms of a final product.
My $0.02 worth.
Sorry if I was too far off-topic...
Caution: Contents under pressure
> But "real design" doesn't work, at least, not very well.
Says who? Works pretty well for me. My team and I are generally *more* productive when we design *before* we code. Ever hear the saying, "Measure seven times, cut once"?
> "Real design," as you call it, requires that you keep to
> yourself, code code code in secret and hope what was
> defined in the beginning is still what the customer wants.
*cough*bull*cough*shit*cough*
A development *team* usually consists of a point person through whom the specs are communicated, an architect who puts together the high level system design (including interfaces if possible), coders who take their cue from the architect, and testers who make sure that the code meets the specifications - thus closing the loop. There is a LOT of communication going on there. However, your team is only as strong as its weakest link. I'll give anyone the boot who can't accomplish their job (as is all to often the case from "wanna get rich, but don't know how to program/test/communicate" kids coming out of school these days).
> The lack of future planning in XP is not a flaw, it's like
> that on purpose. I believe that hacking is the best most
> ideal way to code.
Dear Lord. You people are INSANE. When the f**k are managers going to stop hiring people who actually know more than themselves about programming? No self respecting manager should EVER allow juniors like this guy to decide how development should progress.
Javascript + Nintendo DSi = DSiCade
The steps we follow:
The client approves a demo app after step 3. The client approves the beta version before the testers see it. The client is involved in beta testing.
This system seems to work well for us. The 3-way version of pair programming is beneficial to stringent testing. The fact that we use our own machines (but are free to walk over to any of the other developers) lets us parallelize the development project. Since adopting this system at the suggestion of our manager, our turnaround time has dropped dramatically. Aditionally, our code is better before we hit the beta stage. The last project we did had almost no bugs turn up in beta. The constant black box testing durring development followed by white box testing and fixing before the beta ensured that the code was really good before the testers saw it.
t'nera semordnilap
Have you ever actually tried pair programming?
I'm not an 'exceptional programmer' - I'm just a fucking good one.
When pair programming, I benefit from the expertise and experience of another developer. I avoid making silly mistakes, because he spots them for me. I don't write as many bugs, because he spots them. I don't dither about variable names, or whether to refactor a method, or which algorithm to use - because I have someone to help me keep focussed, someone that helps me make swift decisions, that keeps me on track and moving forwards.
Sure, sometimes I want to read a news story on the web. That's why when pair programming we take a break every hour or two. It depends on the progress we're making, how focussed we are, whether we've got the code to compile and pass all its tests.
Pair programming is not punishment. It's an enlightening experience, a joy to participate in, something I want to do more often.
Nobody is such an exceptional programmer that they can't learn from someone who still needs to look up the language syntax. Lose your ego, open your mind, and actually try PP.
~Cederic