waterfall (was Re: REPOST: Re: Book "python programming patterns". anybody read this??)
Gordon McMillan
gmcm at hypernet.com
Mon Dec 31 09:40:18 EST 2001
Alex Martelli wrote:
[snip]
> This is also known as the "waterfall model" of software development.
>
> It just doesn't work, as many decades of industry experience have amply
> shown.
The "waterfall" model comes from the days when most development was
mainframe batch systems. It "worked" (to some limited degree) in that
environment because of the following conditions:
- there were only a half-dozen or so basic building blocks in mainframe
batch systems (sort, merge, select, extract...)
- the scope of the projects (successfully managed through "waterfall") was
generally tiny compared to the scope of the system in which they fit
- there were senior people on the project who could balance the "top down"
with some "bottom up", but keep it secret
Violate any one of those (too many technical choices; too big a system; or
people who aren't very familiar with the system's context) and the resultant
system was iteration 1 of an iterative prototype too expensive to complete.
More generally, you could describe a successful "waterfall" project as an
iterative prototype that worked the first time through.
What Peter had right was that *thinking* about the problem is always
necessary, even in an iterative prototype :-).
-- Gordon
http://www.mcmillan-inc.com/
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