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Questioning Extreme Programming
In short:
This is bound to a controversial and widely read title -- it is a critical but fair re-examination of all of XP's assumptions and core practices. It provides a much needed comparison of XP with other, less popular, methodologies. Overall, XP emerges favourably, with one serious caveat -- the author concludes that XP is only suitable for a very narrow range of projects, and those that can fulfill all requirements probably stand a significant chance of succeeding using any of the similar methodologies. As with programming languages, there is no silver bullet -- put XP in your methodology toolbox, know when it is appropriate and only use it then.
A couple of interesting specifics:
- The author specifically argues, and I agree, that what the XP literature badly needs is a DSDM 'suitability filter' to advise project leaders as to whether XP is for them.
- In the preface, Kent Beck describes the On-Site Customer role as a team, and not an individual role.
This is the 8th title in The Extreme Programming (XP) Series from Addison-Wesley, surely the most widely read series on a software methodology ever! (If that isn't achievement enough, XP also made testing sexy again. I hear that accountancy firms are looking for Kent Beck to do Public Relations work ...) For those of you who have been living under a rock for the past couple of years the previous titles are:
- Extreme Programming Explained (Beck)
- Planning Extreme Programming (Beck & Fowler)
- Extreme Programming Installed (Jeffries et al)
- Extreme Programming Examined (Succi & Marchesi)
- Extreme Programming in Practice (Newkirk & Martin)
- Extreme Programming Explored (Wake)
- Extreme Programming Applied (Auer & Miller)
This new addition to the XP library feature a foreword by Kent Beck. This is important as many of the reactionary XP fan-club will not like this book -- it challenges XP, and I am delighted to see this title as part of the series. Beck admits he doesn't agree with McBreen's conclusions, but asks you to read the book and decide for yourself, conceding that the arguments are fair and reasoned. I come from a scientific background and distrust anything except wide open debate, a position many who welcome XP will surely agree with. A book challenging XP can only help persuade people to give it a go, by addressing their fears and explaining how to manage any real risk.
Check your sourcesPete McBreen is the author of the excellent Software Craftmanship: The new imperative, a 2002 title from Addison-Wesley. In it he outlines an alternative to the software factory model behind much of traditional software engineering thinking. He proposes a collaborative model with small teams, where the software coder is seen as a craftsman in constant dialogue with the customer. Sound familiar? It should, this is a cross between a methodology and book of advice for career programmers, and fits squarely within the values proposed by the Agile Alliance, and arguably popularised most by XP.
I highly recommend Software Craftmanship, and can think of few authors who are as well positioned to give an analysis of XP as it currently stands.
What is the book about?Questioning Extreme Programming does just that -- it's the first title in the series to take a skeptical look at the rise of this popular methodology and question some of the key assumptions. Arguably there was material like this buried in Extreme Programming Examined, but it suffered from a fragmented, detailed view, due to it being a bound set of conference papers.
The author tackles XP in a fair way -- he's extremely excited by the methodology, and it's clearly in accord with his own preferred approach. What he does is tackle each of the XP tenets in turn, questioning their validity, and then moves on the compare XP to other Agile methodologies and asks how XP stacks up against the competition. He also has a look at the common mis-conceptions (from both sides) about XP, and tackles the key arguments against its adoption in the same way.
Let's have a look at the contents to give you an idea of the structure:
- Introduction.
XP: Hype or HyperProductive? - What is a methodology?
- What do methodologies optimise?
- What are XP projects scared of?
- What do other methodologies consider important?
- What is important for your projects?
- Questioning the Core XP Practices
- Planning incremental development
- Truly incremental development
- Are we done yet?
- Working at this intensity is hard
- Is that all there is to XP?
- Questioning XP concepts
- The source code is the design
- Test first development
- Large-scale XP
- Is the cost of change really low?
- Setting the dials on ten
- Requirements: Documentation or a conversation?
- Is oral documentation enough?
- Playing to win?
- Understanding the XP community
- ReallyStrangeSayings
- Feel the hostility; experience the joy
- Transitioning away from XP
- Your choice
- Is XP for you?
- Do you have a suitable first project?
The whole thing. Let's start with the basics, the high standards of the XP series are maintained, with flawless editing and layout. Moving on, the author's position is admirably neutral -- he is knowledgeable about the field, and although he wants to be converted, he argues only from first principles, and only from the evidence. Similarly, at no point did I think he set up a straw man, or tackled the opposing issues in a different manner. I particularly admired the way he avoided polarising issues -- "All models are lies." -- dismissing them as unhelpful in his current investigation. (He points out that much of the fire in the XP debate has resulted from the use of deliberately polarised opinions as a unambiguous goad to further debate within the XP community. Fine within the gang, inflammatory outside.)
The structuring of the book is of particular interest -- the argument could easily sprawl, but is restrained into very short sub-sections, with each section sporting a clear list of summary bullets. As much as is practical, each challenge to a tenet or practice of XP is discussed independently. (This comes across as simple and straight-forward and you may wonder why I even mention it, but I think it's a fine piece of editing and worthy of praise.)
The sections of the book that I enjoyed most were those dealing with the SmallTalk culture that XP grew out of -- he presents an interesting analysis of why XP works within that environment but discusses how that environment is NOT typical of most development. I have some bias here due to my own experience, see below, but had to agree strongly with his contention that XP is weakest when it comes to team resourcing, and the on-site customer. In particular, he argues that while XP restores dignity and human rights to the programming team, it does so at the expense of the poor frazzled customer. Similarly, he argues that the pre-conditions for XP, in terms of the programming staff, are so high that almost any methodology could be made to succeed with that team.
Don't get the impression that this is a negative work -- it's not. Most of XP emerges intact, and I felt that the author genuinely wanted only to restrain people from adopting XP in inappropriate situations -- not to persuade people to avoid XP. In doing so, he actually protects XP from bad press due to teams failing when trying to adopt XP, them blaming XP itself, rather than their own inappropriate circumstances.
What's bad?Er, not much. He sort of pulls in some material re Open Source early on, but fails to particularly build on that comparison, moving instead to a comparison of Agile methods in closed source circumstances. This is a feeble objection -- but really, it's all I've got this time!
Anything to declare?I should probably give a quick sketch of my background before I finish as I am slightly biased -- most of my work has been in the telecommunications sector, where I either worked with a large code-base (legacy) or a large, distributed team (new development). In no way was I working in the XP style, although I became test-infected easily I found it difficult to even imagine how to apply some of the XP practices to my workplace.
XP changed the way I code and work, for the better, but in a large environment, with no contracting customer, and few experts on a complex domain involving simultaneous hardware development I couldn't see any way to do XP. I'm not saying what we did was good, I'll be the first to admit it was broken (hmm, and I'm unemployed now, time to go and think about cause and effect!). The key assumptions of pure XP just didn't fit the industry I've seen most of. (To be fair, McBreen would have called these projects "systems engineering" and placed them outside of the discussion.) Now that I'm seeking employment again, I'm a lot more aware of methodologies and am much keener to work within an Agile framework, as I believe that all of the methodologies, XP included, offer a much better way of developing software. However, the key point remains -- XP cannot be applied everywhere.
Lastly, I should make it clear that I received a review copy of this title from the publisher and did not pay for it. I paid for my own copy of Software Craftsmanship.
You can purchase Questioning Extreme Programming from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
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We used these four concepts and since the code we put out was so much better than anything our clients had ever paid for, we had more work than we knew what to do with. It was incredible.
Oh-and Boss, take the guys out for a beer at lunchtime every once in a while, and encourage a 5 minute break every hour or so. A happy coder is a good coder.
What are the basic mechanics? Usually, one programmer is typing and thinking out loud about what needs to be done. The other sits and offers suggestions. Sometimes, the keyboard changes hands.
The first few times are not typical. You will spend time discovering tricks with editors and discussing personal work habits. You will find it exhausting, and neither will be unable to type for more than half a day each. Remember to pass the keyboard back and forth, and keep your paired days short.
After the novelty has worn off, you find that every partner is different. Nevertheless, the benefits seem not to depend very much on whom you work with.
What is one guaranteed benefit? All code written by two people is at least understandable to two people. Two people can maintain it, so others are more likely the find the code maintainable as well. Upgrades and bug fixing will always consume more of your time than the negligible first draft of a program. If your code can't be maintained, then you really cannot afford to ship it, no matter how useful the functionality.
Better, the two of you are thinking about the code in different ways. While the typer is thinking about one screenful of code, the companion is thinking about the effects on other code. Maybe this bit of functionality belongs elsewhere. Maybe this information can be encapsulated. Maybe we're making a bad assumption here. You catch many opportunities to simplify your code and improve flexibility.
It's hard to think about the big picture and the details at exactly the same moment. While you're thinking about one, you mess up the other. With twice the brain capacity, one of you can focus on the details, while the other checks the context and adjusts priorities.
I also find that we get more than twice the work done of either of us working alone. A speed-up isn't guaranteed, or even necessary, but there are good reasons why it happens.
Much of the time you spend in front of a terminal is wasted by context switching. "OK. Where was I?" You decide something must be fixed or refactored before you can make any progress. You spend twenty minutes making the extra change and you lose the thread. Your original idea goes cold. Or you postpone and never get back to the necessary refactoring. Worse, you may spend an hour restructuring code, then realize it was not necessary after all. There was a simpler way to solve the same problem, or you misunderstood the problem. Two people will stop each other from wasting many hours this way. One or two such insights can justify the entire session.
Pair programming is also constant code review. You get to discuss and and explain the design at the most optimum moment, when it is being written. Alone, you might get ninety-five percent of a design perfect, so that no one could possibly improve on it. But that stupid five percent could have been avoided by almost anyone you pull in from the hallway. You could have avoided it yourself on Tuesday, but today is Thursday, and you were using a different part of your brain. Two people are less likely to have the same blind spots.
Each programmer has a high tolerance for complexity in certain types of code. Certain strange idioms are second nature to you, but to no one else. You won't know for sure, unless someone is sitting next to you asking "What the heck is that?" Then you'll break the one clever line into several readable lines, and move on.
You'll like your work better, others will like your work better, and you'll get more done. That should be enough reason to give pair programming a try. Maybe it won't work for everyone, or everyday. Don't force yourself or others to participate. You must be relaxed and receptive. As with any new skill, it works better with practice. Try with different partners and different problems. If you find yourself staring blankly at the screen, then surely you can't do any worse with someone else in the room. Try it right then.
What if your programmers work in different cities? Try using an instant messenger, such as IRC, Jabber, or Yahoo's. These allow you to pass files and snippets of code back and forth. You can archive your conversations.
(Reality reasserts itself sooner or later.)
Someone with three questions like this:
:-)
I read the whole article trying to figure out what he was on about. eXtreme Programming? Can anyone give a definition of it? What exactly is it that XP is, and why does this book challenge it? How did XP change the way he codes and works? What is this "popular methodology?" Because that's what I'm most interested in. The author of the above book review assumes everyone has read the book, or knows all about XP. gets modded as Insightfull?
He is not "cluefull" enough to make a google search?
Anyway: XP is set of about 12 "best habits" you should follow in programming.
Whereas other software developmnet processes focus on a lot of work wich is not programming, XP focuses on doing a lot of programming and incorporate the other work: analizis, design, as good as possible into the programming "phase/workflow".
The most known "buzz words" are programming in pairs and unit tests.
But: there are 12
-- Have your programming team at the customer side, or the customer in your house.
-- refactor, if you see a strange couple of lines of code, refactor it
-- only program what you imediatly need, Saying: "You ain't wanna use it". So don't program overabstraced "framework like" code as it likely will get refactored away or won't be needed anyway
-- use storry boards, similar to use cases, well in fact similar to Scenarios, but a lot of literatue mixes up the difference between Use Case and Scenario
-- imediat feed back: make a story board with the customer, see above, prepare a unit test for it, see above, code it, refactor every existing code in your way to support your new story, run the unit tests of teh old story boards to be sure nothing broke during refactoring, run your new unit test to your new story board, show the result to the customer, adjust storyboard and repeat if needed
-- plan the architecture, "play your way through it", buzz word: "planning game", e.g. use CRC cards
-- short releases, plan a day per "story board" or major feature
-- collective ownership, all code belomngs to the team, ther eis nothing like YOUR file/class or code
-- have a system metaphor, thats an architecture pattern, basicly have an other system you can compare your current work with
-- learn and communicate
Well, read a book, get a consultant and DO it.
You won't be able determine if it WORKS or not by trying it half hearted for 3 weeks.
angel'o'sphere
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
I've never heard of it either. Google found this for me. You might be interested in going straight to the What is Extreme Programming page. Based on my quick look through their pages, it seems like just another buzz word for something that isn't really exciting (ooooh, listening to customers and testing throughout the development cycle!? How revolutionary!)