[cap-talk] Throwing down the gauntlet

Ian G iang at systemics.com
Fri Jan 13 10:23:52 EST 2006


John C. McCabe-Dansted wrote:

> David Wagner suggested that it is impossible to write reliable software 
> without bidirectional communication. I am not yet convinced this is the case.

As a generalism I think it is quite true, and I'd
be fascinated if you could find a case where you
could challenge it.  As a comp sci problem it is
called "the coordination problem" I gather although
there isn't an easy / good reference for it.

One of the common things that happens is that designs
ignore this and use uni-directional comms.  Then,
the software becomes "unreliable" and as a consequence
users implement a reliability protocol over the top,
often in meatspace not digitalspace.

The other common failing is to take a "reliable"
protocol like TCP/IP and assume that it reliably
does what you want it to.  Same result, the
unreliability eventually results in a reliability
protocol being added over the top.

iang


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