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From: reggie@paradyne.com (George W. Leach)
Newsgroups: comp.software-eng
Subject: Re: Provocative statement
Message-ID: <1991Apr26.164917.17776@pdn.paradyne.com>
Date: 26 Apr 91 16:49:17 GMT
References: <9776@castle.ed.ac.uk> <1991Apr25.133216.20855@jyu.fi>
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In article <1991Apr25.133216.20855@jyu.fi> sakkinen@jytko.jyu.fi (Markku Sakkinen) writes:
>If the bridge designer wants to have a greater security factor,
>(s)he can specify a little thicker steel and cables than suggested
>by standard calculations.  

	The Brooklyn Bridge is an excellent example of this philosophy.
It was built long before the automobile, and today well after 100 years
it is still going strong.

>The software designer cannot say:
>"This system has to be really safe and secure, so let's put in
>30% more code!"

	No, you miss the point.  Overkill in terms of tolerances.  We expect
to process 1,000 transactions per minute.  Well design for greater than that
number.  Etc.....

	Often, we are constrained by costs.  A bridge is built once and
expected to stand for many years.  Software systems expected lifetimes
are much smaller.  Furthermore, we constantly revamp software systems.

-- 
George W. Leach					AT&T Paradyne 
reggie@paradyne.com				Mail stop LG-133
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