Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!wuarchive!texbell!nuchat!steve
From: steve@nuchat.UUCP (Steve Nuchia)
Newsgroups: news.software.b
Subject: Re: NNTP vs Cnews (was: Re: Cnews is not for me)
Message-ID: <13705@nuchat.UUCP>
Date: 17 Aug 89 13:28:23 GMT
References: <2828@ndsuvax.UUCP> <1989Aug12.221624.12153@utstat.uucp> <1894@ucsd.EDU> <1989Aug13.071802.5187@utzoo.uucp> <527@logicon.arpa> <9636@b-tech.ann-arbor.mi.us> <1989Aug16.182527.24840@utzoo.uucp>
Reply-To: steve@nuchat.sccsi.com (Steve Nuchia)
Organization: Houston Public Access
Lines: 38

In article <1989Aug16.182527.24840@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
[re: relaynews as a daemon]
>You have to think about when caches get flushed:  other things rely on the
>disk being fairly up to date, and flushing everything out is a non-trivial
>part of the current startup/shutdown overhead.  And there are some thorny
>locking issues involved. 

In an nntp environment, which is what I think we should all be
planning future development work for, the disk files cease to
be so significant.  There are good low-overhead ways to implement
single-process database software (record management library level),
e.g. paper from decwrl for which I don't have a handy citation.

>One aspect of it is quite fundamental:  there
>can only be one relaynews running at a time if file updating is to be

This is one very good reason to make it a daemon.  It is also desirable
to have only one copy to ensure that real users can get a cycle in
edgewise.

>done properly, and so you need a way to feed that process from multiple
>sources -- this is very hard to do portably.

Very hard?  It is nontrivial only if you want it to be simultaniously
portable, low latency, and high throughput.  My usual trick is to
write for a simple message passing interface and provide implementations
for sysV IPC, sockets, and named pipes -- and plain files if necessary.
The multiple sources then just need to all use the right library.

>Could be done, but it's not quite as simple as it looks.

Is anything ever as simple as it looks?  If one goes looking for
complexity in a system one will find some.  I still think a long-running
daemon is the way to go.
-- 
Steve Nuchia	      South Coast Computing Services
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