Subject: Re: How accurate is Metcalfe's law? (Was: Ximian software)
From: Ian Lance Taylor <ian@airs.com>
Date: 10 Jan 2002 17:45:59 -0800

"Stephen J. Turnbull" <stephen@xemacs.org> writes:

>     Ian> I have a hard time calling that a diamond of any sort.
> 
> I don't.  I'm impressed.  (But see?  "There you go again," deprecating
> what was arguably a big contribution because technically it was
> "obvious" to you, and just involved "hard work" to implement.)

Just a difference in terminology, I guess.

>     Ian> It was obvious, in the sense I meant in the sentence which
>     Ian> started this whole particular thread (``most good ideas in
>     Ian> software are obvious'').
> 
> Oh, it was, was it?  Then howcum they didn't write it that way in the
> first place?  They could have, no?  But they had better things to do
> at the time.  You picked a right time for a right product.

The original UUCP program had a simple, non-extensible, configuration
system, which was inadequate for most uses and was extended in various
incompatible ways.

The authors of HoneyDanBer UUCP changed this into a set of
configuration files which was oriented around the programs.  This led
to different configuration files used for calling systems and for
handling remote callins.  One file (Permissions) was used for both,
but in different ways.  Most people not deeply familiar with UUCP
think in terms of remote systems, not the UUCP program suite, and
don't separate those two concepts.  The Permissions file in particular
was easy to misunderstand, and many people unintentionally configured
a security hole.

(BTW, qmail is another system which uses configuration files based on
the program view rather than on the user view; for example, think
about the relationship between the control files rcpthosts, locals,
and virtualdomains.  Fortunately there is no equivalent security
problem.)

I switched the configuration file system around into what I felt was a
user-comprehensible view.  Then I asked for input on Usenet:
    http://groups.google.com/groups?hl=en&selm=2399%40airs.com
(over ten years ago, now).  The responses helped me polish the system
(several people commented that they wanted support for the old
configuration files, so I added that also).

> So tell me.  Today people emulate your configuration system (and try
> to beat it, and by now often do, I suppose).  Who were you emulating?
> Or did you have to reorganize the configs and documentation yourself?

I wasn't emulating anybody.  The general approach was a keyword value
format, which is of course pretty common.

Ian