Hal Merritt wrote:
I have been curious about this so called "Christmas Tree Virus" for many
years. I hear it mentioned, but have never been able to verify it as a
real event or urban legend.
His use of "so called" is appropriate, Here, as elsewhere, it is important
to try to avoid confounding malice and incompetence.
This generic problem has a long history.
The early, ca. 1965, versions of the SABRE airlines reservation system had a
global-broadcast facility that permitted the text of a single message to be
sent to all K known destinations. Intended for such uses as warning of an
impending system shutdown, it might have been valuable and shoiuld have been
innocuous; but it was neither.
It was implemented by using the SABRE destinations table to construct K full
copies of the message, one for each destination, each of which was then
enqueued in the usual way for transmission. The resulting buffer [storage]
shortage brought SABRE to its knees, and recovery was preternaturally slow.
An alternatiive implementation that reused a single copy of the message text
would have been innocuous, and that is the moral of this little story. Bad
design can be as lethal as malign intent.
John Gilmore
Ashland, MA 01721-1817
USA
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