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From Ben Laurie <...@algroup.co.uk>
Subject Re: request for review: server/config discussion
Date Tue, 20 Jul 1999 21:12:48 GMT
James Todd wrote:
> 
> "Carreira, Jason" wrote:
> >
> > If those values depend on values in the config construct, they should
> > regsiter themselves as listeners to receive changes from the config object.
> 
> craig has expressed this request as well and i do like
> the idea that "a config service listener" can choose to
> act on config detail changes as deemed appropriate. as i
> see it, there are two main features (and a couple of sub
> features):
> 
>         translate "persistified config data" to the relevant
>         objects
> 
>         provide a multi-protocol service to config data
>         consumers (aka listeners) to:
> 
>                 read config data (eg server)
> 
>                 read/write config data (eg tools)
> 
>                 notify (actively or passively) listner
>                 that a config change has occurred since
>                 the last request
> 
> each of these do need to be stated a bit more explicitly
> for review but i do believe there is a common goal taking
> form here.

Much as I like the idea of notifying config changes, I think it is
likely to lead to trouble. Here's the problem in a nutshell: either you
notify in detail what the changes are, in which case we are looking at
horrendous complexity and likely lots of interesting failure modes, or
you just say "it's changed" in which case you only need a single module
that requires a restart (canonical example: Apache listeners - these
cannot change without a restart) and every change gives you a restart
anyway.

I suppose its possible that there's some middle ground, but I'm afraid
my imagination has failed me...

Cheers,

Ben.

--
http://www.apache-ssl.org/ben.html

"My grandfather once told me that there are two kinds of people: those
who work and those who take the credit. He told me to try to be in the
first group; there was less competition there."
     - Indira Gandhi

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