Re: [Xen-devel] [PATCH] Convert shutdown to use xenstore

[Rusty Russell <rusty@xxxxxxxxxxxxxxx>]

On Fri, 2005-08-05 at 02:58 +0100, Mark Williamson wrote:
> Hi Dan,
> 
> Any reason not to use textual data in the store rather than numbers?  IMO 
> it'd 
> make it a little more readable - numbers only make sense if you have the 
> header file - but I don't know if there's a convention on this.

If something fundamentally *is* a number, or an ordinal, that's one
thing.  But otherwise, a simple value is better.

We've seen this in sysfs and Open Firmware; the only defence against
crap accumulating in the store is constant vigilance.  This is only
likely if it's actually useful to browse the thing, ie. as consistent
and human-readable as possible.  This is also an end in itself:
something that is self-evident and easy to understand is easier to
maintain ("hey, I was using the lower bit of that value to determine if
it's read-only, and you broke it!" vs "you removed the field called
"read-only").

An ideal system is one where I can implement a new backend, frontend or
tool simply by looking at the paths and values in the store.  It also
has clear implications for diagnosing problems.

Cheers,
Rusty.
-- 
A bad analogy is like a leaky screwdriver -- Richard Braakman


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