Matt,

On Fri, 20 Aug 2004 12:51:10 -0500, Matt Pobursky wrote:

>...<
> An old engineer once told me "Good design really shows up not when
> things go right, but when things go wrong".

I agree completely!

> Maybe it's just the industries I typically design for (high reliabilit=
y
> industrial controls and medical electronics) but I find as much of my
> design work goes into asking "but what if... ?" questions and providin=
g
> graceful failure modes as goes into the actual normal product operatio=
n
> itself.

Unfortunately in the IT industry the common way to create a system is to=
 get a specification from the User as
to what they want, do an outline design, get them to agree it, do a deta=
iled design, get them to agree it,
then build and test it to the spec.  If it meets the spec, it is deemed =
to be finished.  Nowhere in here is
there a "Yes, but..." stage, which I have always advocated, but which a =
lot of others think is a Bad Thing!

You cannot rely on the user (or whoever takes that role, in the case of =
commercial products) to mention or
spot problems because they may have no experiance in such things.  It is=
 up to the professional to look at the
design and try to spot the potential problems, and to design around them=
.  But it's rarely taught, and even
more rarely actioned, because time and money budgets are usually too tig=
ht.  This is where =A31million
electricity bills come from!

> It's something I seem to see less and less of in designs I review as
> time goes by and it's kind of scary.

Indeed, and it frightens me in particular where safety-critical systems =
(Nuclear power stations, Fly-by-wire
aircraft controls, traffic lights, ABS systems etc) are concerned.  But =
it also applies to stock control,
invoicing, payroll, VCRs, alarm systems, and so on, where anomalies shou=
ld be tested-for and reported, even if
it's not possible for the system to fix them itself.

Cheers,


Howard Winter
St.Albans, England

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