--- In [EMAIL PROTECTED], "Kent Beck" <[EMAIL PROTECTED]> wrote: > I am an interested reader about lean manufacturing, so I hope if I say > something wrong here that someone with experience will correct me. My > understanding is that lean production lines deliberately mix their > output, unlike mass production lines which try to maximize the number of > identical outputs to reduce setup costs. Originally this was because the > market for cars in Japan was small and fragmented and no more than a few > of each model could be sold. In practice, this reduces the risk that any > one failure will totally shut down the line (that's my understanding, I > don't think I've ever seen this explicitly stated). > > Kent Beck > Three Rivers Institute
Interesting that we seem to have gotten different perceptions. I'd certainly agree that one effect would be to reduce the risk of blocking production, but the reason I've always seen in the literature is to minimize in-process inventory, which is one of the seven categories of waste. Another way I've seen it put is that you never build anything until you've got an order for it, and that policy is applied recursively through the entire supply chain, from the ultimate consumer all the way back to the raw material supplier. I'm not sure what time scale you mean when you say "mix their output." Setup still costs something, so it's not like they do one of each in sequence. My understanding is that minimizing the time required to change setups is a very important optimization, but it's not like it goes to zero. Minimizing in-process inventory seems to be a fairly important theme in XP anyway; the only places where I see in-process inventory building up in the XP process is stories waiting to be developed and finished software waiting to be deployed, and I have heard of shops that do (reasonably) continuous deployment. John Roth > > > -----Original Message----- > > From: Luiz Esmiralha [mailto:[EMAIL PROTECTED] > > Sent: Thursday, November 04, 2004 10:58 AM > > To: [EMAIL PROTECTED] > > Subject: Re: Software Factories Considered Harmful (was RE: > > [XP] Why NOT XP?) > > > > > > > > Kent, > > > > Could you ellaborate a bit further? Do you mean the same > > production line could be used to produce products that share > > common "parts" thus enhancing overall productivity (beat ya > > on the product-related word count)? > > > > Seriously, I see lots of incoherences between software > > creation and mass production: > > > > 1) In a mass production line, work is handed over from > > machine to machine (even if the machine is called Joe and > > likes to drink a Bud in his lunch). In software production, > > handovers are made between thinking entities with very fuzzy > > interfaces (humans). Communication overload/overhead is more > > of a problem here. > > > > 2) Stupid, drone work consumes very little of a software > > project's schedule. Someone measured that 90% of a > > programmer's time is spent thinking (or faking it). > > > > 3) The level of customization demanded by software customers > > is higher than in any other industry. This adds to the cost > > of adapting your factory to new technologies, new > > requirements, new knowledge domains. > > > > I can see some resemblance between software development and > > mass production from a 10,000 feet perspective, but looking > > closer I find these two to be different beasts. > > > > Of course I'm not Kent Beck (grovel) so my oppinion is worth > > about a dented dime. But it's mine and I cherish it. :) To Post a message, send it to: [EMAIL PROTECTED] To Unsubscribe, send a blank message to: [EMAIL PROTECTED] ad-free courtesy of objectmentor.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/extremeprogramming/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
