Re: A Customer's Request For Open Source Software

[Christopher Browne <cbbrowne@acm.org>]

In an attempt to throw the authorities off his trail, Marin David Condic <nobody@noplace.com> transmitted:
> If you started with a "Single User" system, then all operations can
> take place in RAM - of whatever sort. This would be no different
> than editing a document with a word processor that is not
> journaling. If you take a power hit, you lose your work to that
> point in time. You get done posting transactions or generating
> reports - you "Exit - Save" and your work is written to a
> database. (The simplest form would be a stream file where you do a
> 'Write for your data structure.)
>
> From there, you can consider if you want to make this a multi-user
> system.

There is a strong tendancy for systems designed in this manner to NOT
play well when they move over to allow concurrency.  I think I can
characterize it all in one word: "Windows."

In spite of there being Windows NT around, which _was_ designed as a
multiuser multitasking system, since so much of the software had its
genesis with companies that assumed ONE user running ONE program on
some variation of Windows 95, which was a thin layering of GUI atop
MS-DOS, what we see now is that "Windows applications" are basically
designed for a single user OS, and most don't play well if you have
multipel instances of things around.

Concurrency is _hard_, and if you don't design it in at the beginning,
it is quite likely that by the time you get around to it, the system
design will probably preclude having it _really_ work...
-- 
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