Any one practice doesn t stand well on its own (with the possible exception of testing). They require the other practices to keep them in balance. [1]
”Kent Beck
Well, from my experience, most teams that say they re doing XP don t actually do the practices. [2]
”Alistair CockburnHouston, we have a problem. [3]
”Jim Lovell
Cockburn s comment isn t just an off-the-wall quip about XP: He discusses this particular concern in several other forums. For example, he also describes XP as a high discipline methodology ”it takes a lot of sustained effort to adhere to XP s practices. [4] This is a fundamental problem with XP, combined with the methodology s fragile nature.
XP is a symbiotic process ”that is, you really need to do all of XP or none at all. There s no in-between (unless you perform some very careful and deliberate tailoring). The theory is that each of these individually flawed practices reinforces each other to produce something stronger. Unfortunately, this can also work in the other direction: Stop doing one and the chain unravels. In the real world it proves difficult to adhere to the XP practices for the duration of an entire project.
[1] Kent Beck, op. cit., p. 33.
[2] Kent Beck, Extreme Programming Explained: Embrace Change (New York, NY: Addison-Wesley, 2000), p. 69.
[3] Alistair Cockburn posting to the C2 Wiki page XP and the CMM, http://c2.com/cgi/wiki?XpAndTheCmm .
[4] Jim Lovell, Captain of Apollo 13, April 13, 1970.