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

Jerome Alet alet at librelogiciel.com
Thu Jun 10 10:26:31 PDT 2004


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

bye

Jerome Alet





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