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Date:      Sat, 15 Jun 2002 15:18:43 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Mike Makonnen <makonnen@pacbell.net>
Cc:        current@FreeBSD.ORG, danny@cs.huji.ac.il, gordont@gnf.org
Subject:   Re: HEADS UP: rc.d is in the tree
Message-ID:  <3D0BBD43.6623BCBD@mindspring.com>
References:  <E17IrYC-000NFi-00@cse.cs.huji.ac.il> <20020614142308.7ddeaed0.makonnen@pacbell.net> <3D0A6E7B.F243329A@mindspring.com> <20020615121247.A6971@dragon.nuxi.com> <3D0B9A60.A4A816A4@mindspring.com> <20020615144656.06f8404d.makonnen@pacbell.net>

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Mike Makonnen wrote:
> On Sat, 15 Jun 2002 12:49:52 -0700
> Terry Lambert <tlambert2@mindspring.com> wrote:
> > David O'Brien wrote:
> > > On Fri, Jun 14, 2002 at 03:30:19PM -0700, Terry Lambert wrote:
> > > > I.e. if "REQUIRE" describes soft dependency ordering, what
> > > > describes hard dependency ordering?
> > >
> > > Why the need to distingish?
> >
> > Otherwise circular dependencies.
> 
> That's what rcorder(8) is there for.

It's not that simple.

The most obvious example is the need to use DNS in order to look
up syslog hosts, and whether you start syslogd before you start
DNS, if DNS needs to syslog errors.

Since the DNS information is only used by syslogd when actual
logging to a remote host takes place, it should be possible to
say that syslog has a soft dependency on DNS, and DNS has a hard
dependency on syslog.

Similar arguments can be made about "sendmail", but the example
is less obvious, since it involves local configuration, and the
mailing of things like cron job output.


In fact, any daemon you run will import N services and export M
services.  The natural rendesvous is actually on the dependency
on a particular service, as opposed to dependency on a psrticular
set of code implementing a service (e.g. it's a seperate program
in DJBDNS to export TCP based DNS services and/or DNSXFR services,
and there are many programs that can export HTTP services on port
80 or SMTP services on port 25 or POP3 services on port 110).

-- Terry

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