[cups.general] Re: query about the cups class scheduling algorithm

[Helge Blischke]

Jerome Alet wrote:
> 
> Hi,
> 
> On Thu, Jun 10, 2004 at 01:52:28PM +0200, Helge Blischke wrote:
> > Anonymous wrote:
> > >
> > > Ashley GC wrote:
> > >
> > > > I would like the cups scheduler to know what printers are available,
> > > > either by pinging the printer regularly, or by assuming the printer
> > > > is available and if the tcp connection times out, moving the job to
> > > > a different queue in the same class.
> > > > And if all this could be on the webpage(http://server:631/classes/cl)
> > > > then that would be nice.
> > >
> > > These features are essential. Reading the CUPS documentation one sees;
> > >
> > >  "In addition, CUPS can automatically merge multiple identical
> > >   network  printers into "implicit classes". This allows clients
> > >   to send jobs to the implicit class and have them print on the first
> > >   available printer or server"
> > >
> > > The trouble is, as Ashley and others have pointed out, detecting the availablity of a
> > > printer in CUPS is touch and go. A printer can be offline, out-of-paper or thrown out
> > > the window and CUPS will happily report that the printer is ready. So is there
> > > back-channel support or not ? The FAQ says not until version 1.2 which seems
> > > at odds with the documentation. Could someone give a quick appraisal of the situation,
> > > please or tell me what we are doing wrong.
> >
> > As CUPS 1.1 is designed, I think there is no general easy solution. I'd
> > guess CUPS 1.2 will
> > implement something like this making use of the IPP notify objects for
> > real IPP printers.
> 
> With most network printers you could use SNMP.
> 
> Install snmpd and snmptrapd
> 
> Whenever your printer falls in error status, it sends an SNMP trap
> to the snmptrapd server, which can execute any script of your choice,
> for example a script which would do in-depth diagnostic and act
> accordingly
> 
Yes, SNMP is a good tool for sysadmins to know what's up on their
network and for
maintenance purposes, but there is - AFAIK - no suitable interface to
interact with
CUPS. Perhaps you file a RFE.

Helge

-- 
H.Blischke at srz-berlin.de
H.Blischke at srz-berlin.com
H.Blischke at acm.org