Re: [xml-dev] The Airplane Example (was Re: [xml-dev] StreamingXML)

[Elliotte Rusty Harold <elharo@metalab.unc.edu>]

At 7:03 AM -0800 12/31/04, Benjamin Franz wrote:

>People treat software like it isn't real. Software machines are just 
>as real as hardware machines - and often control hardware machines. 
>If you are killed by a radiation therapy machine because of broken 
>software - you are just as dead as if the cause was broken hardware.

Yes, but there is a qualitative difference between software failures 
and hardware failures (though the effects of either can be equally 
damaging). Software mostly fails due to outright bugs and failure to 
anticipate certain conditions it encounters. However, if it works in 
a certain condition, it always works. Hardware can fail for these 
reasons, but it also has an additional way to fail most software 
doesn't: it decays over time as parts wear. It is completely 
plausible for a piece of hardware to work 10,000 times in a row and 
then fail the 10,001st time, even though nothing has changed. This 
style of failure is very rare for software. Software needs to be 
upgraded and maintained to handle changes in the environment where 
the software runs, not because the software wears out.
-- 

   Elliotte Rusty Harold
   elharo@metalab.unc.edu
   Effective XML (Addison-Wesley, 2003)
   http://www.cafeconleche.org/books/effectivexml
   http://www.amazon.com/exec/obidos/ISBN=0321150406/ref=nosim/cafeaulaitA