Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Wed 29 Jul 2015 at 14:21:20 +0200, Tuxo Holic wrote:

> Thanks Brian and Jochen for the efforts, but switching off services to
> remove the queue and end up with no advertised printer is not an
> option as well.

So you want the printer to be advertised. In your first mail you said:

  I'd prefer network printers to be invisible on the client side, as
  long as they are not online.

Now you want them visible. Why?
 
> So the main goal I was aiming at seems to be not available which was:
> give notification to the user, that this network printer is switched
> off or out of service due to maintenance, paper jam or what other
> reason you could think of.

Adapt the script to do

  cupsreject -r "PrinterSwitchedOff" HP_LaserJet_1020

Tested successfully on a client not running cups, which was something
else you were interested in. 


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Re: cups/cups-browsed: only advertise online network printers

[David Wright]

Quoting Tuxo Holic (tuxoho...@hotmail.de):
> Thanks Brian and Jochen for the efforts, but switching off services to remove
> the queue and end up with no advertised printer is not an option as well. So
> the main goal I was aiming at seems to be not available which was: give
> notification to the user, that this network printer is switched off or out of
> service due to maintenance, paper jam or what other reason you could think of.

I can only think of 4 notification methods, but perhaps others can
come up with better ones:

wallinstantaneous, ephemeral and local
email   instantaneous, persistent and potentially global
/etc/motd   displayed at login but, after that, would need to be checked
/etc/issue  displayed before login but, after that, would need to be checked

Personally I always print through scripts which makes the problem
trivial, but I understand this is not everyone's way of working..

Cheers,
David.


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RE: cups/cups-browsed: only advertise online network printers

[Tuxo Holic]

Thanks Brian and Jochen for the efforts, but switching off services to remove 
the queue and end up with no advertised printer is not an option as well.

So the main goal I was aiming at seems to be not available which was: give 
notification to the user, that this network printer is switched off or out of 
service due to maintenance, paper jam or what other reason you could think of.  
 

Re: cups/cups-browsed: only advertise online network printers

[Jochen Spieker]

Brian:
> 
> A=$(lsusb | grep -i 'Stylus Color 740')
> if [ -z "$A" ]; then
>systemctl stop cups.service cups.socket cups.path
> fi
> 
> (No sniggering at the back, please. I'm aware of the deficiencies in the
> logic. Improvements are welcome).

I would have phrased it something like this:

if ! lsusb | grep -qi 'Stylus Color 740'; then
   systemctl stop cups.service cups.socket cups.path
fi

grep exits with > 0 if it doesn't find your pattern. In this case you
can use -q to prevent grep from printing matching lines on stdout.

Ugly one-liner:

lsusb | grep -qi 'Stylus Color 740' || systemctl stop cups.service cups.socket 
cups.path

"EITHER grep finds something OR I want to shut down Cups."

J.
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[Agree]   [Disagree]
 


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Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Tue 28 Jul 2015 at 15:53:47 +0100, Brian wrote:

> On Tue 28 Jul 2015 at 10:35:33 +0200, Tuxo Holic wrote:
> 
> > Which brings me back to my previous question: Seems to me "server
> > cups" knows that printer is not running yet, how can I make "server
> > cups" tell this to "client cups" , so the users gets the feedback in
> > the printing app? My idea would be some sort of notification like
> > "please switch on printer "HP_LaserJet_1020" .
> 
> There is a wiki page for Tea4CUPS. It might give you some ideas.

The idea of users getting feedback doesn't appeal to me. If they do not
see the print queues they have nothing to print to.

You seem reluctant to switch off a printer and issue a command on the
computer. Is multitasking out of fashion? It seems to me it solves your
problem so, apart from what follows, I don't think I have much more to
say on the matter.

On the server run a script as a daemon or a cron job. It removes the
queues when the printer is switched off. My example is for a USB printer.

A=$(lsusb | grep -i 'Stylus Color 740')
if [ -z "$A" ]; then
   systemctl stop cups.service cups.socket cups.path
fi

(No sniggering at the back, please. I'm aware of the deficiencies in the
logic. Improvements are welcome).


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Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Tue 28 Jul 2015 at 10:35:33 +0200, Tuxo Holic wrote:

> Okay Brian - here's the update of further testing:
> I need one BrowsePoll line enabled so the cups-browsed clients know
> what hostname or IP they should poll,which leaves me with the
> following *not default* but very simplistic cups-browsed.conf
>
> grep -v ^# /etc/cups/cups-browsed.conf
> BrowseRemoteProtocols dnssd cups
> BrowsePoll 192.168.1.1:631 #could use Server1 as hostname with the same effect
>
> LANG=C lpstat -t
> scheduler is running
> no system default destination
> device for HP-LaserJet-1020:
> ipp://192.168.1.1:631/printers/HP_LaserJet_1020
> HP-LaserJet-1020 accepting requests since Tue 28 Jul 2015 10:04:34 AM CEST
> printer HP-LaserJet-1020 is idle.  enabled since Tue 28 Jul 2015 10:04:34 AM 
> CEST

> Let me be clear, that without a BrowsePoll line I end up with no
> search result in lpstat .

I do not understand that. BrowsePoll is  in cups-browsed to provide
backwards compatibility with server versions < 1.6.x. Servers > 1.6.x
do not respond to CUPS packets.

  BrowseRemoteProtocols dnssd

should be the only line necessary for you in cups-browsed.conf.

> I successfully removed the cups-browsed package from the server which
> leaves cups alone to share printers on the server side.
>
> I can remove the cups package on the client, but doing so I end up
> with cups-browsed being unusable. Reinstalling cups right away and it
> will work again. Conclusion: seems to me cups should be a dependency
> for cups-browsed, in Debian/Jessie. Either it is not or I messed up my
> apt environment.

cups-browsed is not unusable; it does not require cups-daemon in order
to work, which is what is meant by a dependency. Iceweasel will display
print queues without cups on the system by having avahi-daemon inform
cups-browsed of the ones it knows about. Granted, libcups2 is required.

> >> Clients see print *queues*, not printers. Print queues are advertised by
> > the server. The on/off status of the printer is immaterial. If you do not
> > want the clients to see the queues do
> > 
> > systemctl stop avahi-daemon.service>

'systemctl stop avahi-daemon.socket' may also be needed.

> I get that, but it still is cause for confusion to some people,
> because there is no way to distinguish a queue of a running printer to
> a queue of a *not* running printer. You can successfully hit print and
> there is no feedback whatsoever in the application, that next you
> should get up and switch on your printer.

It only leads to confusion if you neglect to do

  systemctl stop cups.service cups.socket cups.path

before or after switching the printer off. :)

> Which brings me back to my previous question: Seems to me "server
> cups" knows that printer is not running yet, how can I make "server
> cups" tell this to "client cups" , so the users gets the feedback in
> the printing app? My idea would be some sort of notification like
> "please switch on printer "HP_LaserJet_1020" .

There is a wiki page for Tea4CUPS. It might give you some ideas.


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RE: cups/cups-browsed: only advertise online network printers

[Tuxo Holic]

Okay Brian - here's the update of further testing:
I need one BrowsePoll line enabled so the cups-browsed clients know what 
hostname or IP they should poll,which leaves me with the following *not 
default* but very simplistic cups-browsed.conf
grep -v ^# /etc/cups/cups-browsed.conf
BrowseRemoteProtocols dnssd cupsBrowsePoll 192.168.1.1:631 #could use Server1 
as hostname with the same effect
LANG=C lpstat -t
scheduler is running

 no system default destination  

  device for HP-LaserJet-1020: 
ipp://192.168.1.1:631/printers/HP_LaserJet_1020 
   HP-LaserJet-1020 accepting requests 
since Tue 28 Jul 2015 10:04:34 AM CEST  
 printer HP-LaserJet-1020 is idle.  enabled 
since Tue 28 Jul 2015 10:04:34 AM CEST
Let me be clear, that without a BrowsePoll line I end up with no search result 
in lpstat .
I successfully removed the cups-browsed package from the server which leaves 
cups alone to share printers on the server side.
I can remove the cups package on the client, but doing so I end up with 
cups-browsed being unusable. Reinstalling cups right away and it will work 
again. Conclusion: seems to me cups should be a dependency for cups-browsed, in 
Debian/Jessie. Either it is not or I messed up my apt environment.
>> Clients see print *queues*, not printers. Print queues are advertised by
> the server. The on/off status of the printer is immaterial. If you do not
> want the clients to see the queues do
> 
> systemctl stop avahi-daemon.service>
I get that, but it still is cause for confusion to some people, because there 
is no way to distinguish a queue of a running printer to a queue of a *not* 
running printer. You can successfully hit print and there is no feedback 
whatsoever in the application, that next you should get up and switch on your 
printer.
Which brings me back to my previous question: Seems to me "server cups" knows 
that printer is not running yet, how can I make "server cups" tell this to 
"client cups" , so the users gets the feedback in the printing app? My idea 
would be some sort of notification like "please switch on printer 
"HP_LaserJet_1020" .
  

Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Mon 27 Jul 2015 at 14:17:52 +0200, Tuxo Holic wrote:

> > On Sun, 26 Jul 2015 20:28:21 +0100, Brian wrote:
> 
> > Your problem (please correct me if I have not understood what you said)
> > is that applications, Iceweasel, Evince etc, still see HP_LaserJet_1020
> > after the server is closed down.
> 
> No, I meant: the server usually stays on until I go to bed, but the
> printer is switched off right away as soon as I no longer use it.
> Clients still see that printer, even after I switched it off.
> And: they also see that printer, if only the server started, with the
> printer still beeing switched off.

Clients see print *queues*, not printers. Print queues are advertised by
the server. The on/off status of the printer is immaterial. If you do not
want the clients to see the queues do

  systemctl stop avahi-daemon.service

at the same time you switch off the printer.

> >> >> BrowseAllow 192.168.1.1
> >> BrowseAllow Server1
> >> BrowsePoll Server1:631
> >
> > Into unknown territory! What's wrong with the defaults? Your server is
> > advertising; the default 'BrowseRemoteProtocols dnssd cups' on the
> > clientworks well, What need is there for these?
> 
> One problem here: The advertising with the default values doesn't work
> since every line responsible for "Browsing" is disabled with a
> comment. For advertising to work on the client, I need at least one
> valid line with either the Printserver IP or the Printserver Hostname
> or the Printserver Subnet.

Your server broadcasts Bonjour packets. Your client machines pick them
up and, with the help of cups-browsed, create local raw queues. There is
no need for the server to use CUPS broadcasts or have cups-browsed on
it.

> > What versions of cups are running on the clients?
> 
> Debian/Jessie on client & sever > 1.7.5

> This means: it is newer than 1.6 thus needs the cups-browsed package
> to advertise network printers, right?

Only needed on the client to browse Bonjour broadcasts, not for
advertising. Please see cups-browsed(8) and the README.Debian for cups.

> A question here: Do I need  to install it on the server as well?

Only if you want it to broadcast queues using the CUPS protocol. Do you?
Why?

> Because like I explained I only changed the client configuration, but
> I changed nothing on the server, which means: I  installed both cups &
> cups-browsed there as well, but left the configuration unchanged as
> far as configuring the printer using the cups webinterface goes: 
> > Find printer > select recommended driver > add printer > select share this
> > printer > save changes > cups restarted.
> I'm not even sure I absolutely need cups on the client ... it might be enough
> to have cups-browsed installed there, in order to find my network printer.

You should try it. :)

> Can you elaborate on the role cups and cups-browsed share these days? Do both
> services have to run on client AND server?

Please see above.


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RE: cups/cups-browsed: only advertise online network printers

[Tuxo Holic]

> On Sun, 26 Jul 2015 20:28:21 +0100, Brian wrote:

> Your problem (please correct me if I have not understood what you said)
> is that applications, Iceweasel, Evince etc, still see HP_LaserJet_1020
> after the server is closed down.

No, I meant: the server usually stays on until I go to bed, but the printer is 
switched off right away as soon as I no longer use it.
Clients still see that printer, even after I switched it off.
And: they also see that printer, if only the server started, with the printer 
still beeing switched off.
>> >> BrowseAllow 192.168.1.1
>> BrowseAllow Server1
>> BrowsePoll Server1:631
>
> Into unknown territory! What's wrong with the defaults? Your server is
> advertising; the default 'BrowseRemoteProtocols dnssd cups' on the
> clientworks well, What need is there for these?
> 

One problem here: The advertising with the default values doesn't work since 
every line responsible for "Browsing" is disabled with a comment. For 
advertising to work on the client, I need at least one valid line with either 
the Printserver IP or the Printserver Hostname or the Printserver Subnet.
 AutoShutdown On
>>
> You have a reason for this? One which stands up to scrutiny?
>

Nope, let's remove this then, it has nothing to do with the issue at hand.

> 
> What versions of cups are running on the clients?
> 

Debian/Jessie on client & sever > 1.7.5
This means: it is newer than 1.6 thus needs the cups-browsed package to 
advertise network printers, right?
A question here: Do I need  to install it on the server as well? Because like I 
explained I only changed the client configuration, but I changed nothing on the 
server, which means: I  installed both cups & cups-browsed there as well, but 
left the configuration unchanged as far as configuring the printer using the 
cups webinterface goes: 
> Find printer > select recommended driver > add printer > select share this 
> printer > save changes > cups restarted.
I'm not even sure I absolutely need cups on the client ... it might be enough 
to have cups-browsed installed there, in order to find my network printer.
Can you elaborate on the role cups and cups-browsed share these days? Do both 
services have to run on client AND server?
Because there is one other thing I noticed:
apt-cache show cups-browsed
Package: cups-browsedSource: cups-filtersVersion: 1.0.61-5Installed-Size: 
191Maintainer: Debian Printing Team 
Architecture: amd64Depends: libavahi-client3 
(>= 0.6.16), libavahi-common3 (>= 0.6.16), libavahi-glib1 (>= 0.6.16), libc6 
(>= 2.4), libcups2 (>= 1.6.0), libglib2.0-0 (>= 2.14.0), init-system-helpers 
(>= 1.18~)Recommends: avahi-daemon (>= 0.6.31-3~)Enhances: cups
cups is not a dependency here, it's considered an enhancement... it might be 
worth a try to remove cups on the client ... I never connect printers there, 
they will never offer a printer, but  always will have to discover a network 
printer.
  

Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Sun 26 Jul 2015 at 17:54:50 +0200, Tuxo Holic wrote:

> On Sat 25 Jul 2015 at 11:30:30 +0100, Brian wrote:
> 
> > Please stop cups-browsed on the client and post the output of 'lpstat -t'.
> 
> systemctl stop cups-browsed.service
> 
> systemctl status cups-browsed.service
> ● cups-browsed.service - Make remote CUPS printers available locally
>    Loaded: loaded (/lib/systemd/system/cups-browsed.service; enabled)
>    Active: inactive (dead) since Son 2015-07-26 17:27:01 CEST; 1s ago
>   Process: 22426 ExecStart=/usr/sbin/cups-browsed (code=exited, 
> status=0/SUCCESS)
>  Main PID: 22426 (code=exited, status=0/SUCCESS)
> 
> Jul 26 17:27:01 systemd[1]: Stopped Make remote CUPS printers available 
> locally.
> 
> LANG=C lpstat -t
> scheduler is running
> no system default destination

Your problem (please correct me if I have not understood what you said)
is that applications, Iceweasel, Evince etc, still see HP_LaserJet_1020
after the server is closed down.

This would be possible if you had set HP_LaserJet_1020 as the system
default destination. cups-browsed removes all discovered printers from
the client if they disappear (which they do when the server shuts down),
except for the one which is marked as the default on the client.

This was my first thought. It turns out that first thoughts are not
always fruitful. You have no default destination. Back to the drawing
board!

> lpstat: No destinations added.
> lpstat: No destinations added.
> lpstat: No destinations added.
> lpstat: No destinations added.

cups sees no printers. Not surprising because cups-browsed is awol
(absent without leave) and has nothing to tell it.

Do your applications still see HP_LaserJet_1020 after doing this?
 
> systemctl start cups-browsed.service
> 
> LANG=C lpstat -t
> scheduler is running
> no system default destination
> device for HP-LaserJet-1020: ipp://Server1:631/printers/HP_LaserJet_1020
> HP-LaserJet-1020 accepting requests since Sun 26 Jul 2015 05:27:42 PM CEST
> printer HP-LaserJet-1020 is idle.  enabled since Sun 26 Jul 2015 05:27:42 PM 
> CEST

cups-browsed has returned. It communicates with cups about some IPP
(CUPS) packets it is has received.

> So basically with the browsed.service stopped the broadcasts are ignored?

More or less. To repeat: the main purpose of my question was to discover
whether you had a default print queue set up. You don't.

> Let me give you the client's /etc/cups/cups-browsed.conf as well:
> 
> grep -v ^& /etc/cups/cups-browsed.conf 
> 
> BrowseRemoteProtocols cups

You are only accepting the IPP (CUPS) protocol to discover printers on
the network. No problem, but if you have avahi-daemon running it is
wasting its time.

> BrowseProtocols cups

A repeat of the previous directive for discovering printers. Unless you
have printers connected to the client it does nothing. Probably not a
problem.

> BrowseAllow 192.168.1.1
> BrowseAllow Server1
> BrowsePoll Server1:631

Into unknown territory! What's wrong with the defaults? Your server is
advertising; the default 'BrowseRemoteProtocols dnssd cups' on the
clientworks well, What need is there for these?

> AutoShutdown On

You have a reason for this? One which stands up to scrutiny?

> Now, this is interesting:
> 
> After I played around with the client's cups-browsed service the printer 
> status on the server1 webinterface changed:
> 
> Before:
> HP LaserJet 1020 HP LaserJet 1020 Foomatic/foo2zjs-z1 (recommended) Idle - 
> "Waiting for jobs"

That looks ok.

> After:
> HP LaserJet 1020 HP LaserJet 1020 Foomatic/foo2zjs-z1 (recommended) Idle - 
> "Waiting for printer to become available."

That looks ominous.

> And the printer page on the server1 webinterface does always mention:
> HP_LaserJet_1020 (Idle, Accepting Jobs, Not Shared)
>
> Any thought's on the matter?

What versions of cups are running on the clients?

> Please CC me with your reply, I forgot to mention I'm no longer subscribed to 
> the list.

It would be as well to repeat this in other posts. Memories are fallible.


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RE: cups/cups-browsed: only advertise online network printers

[Tuxo Holic]

On Sat 25 Jul 2015 at 11:30:30 +0100, Brian wrote:

> Please stop cups-browsed on the client and post the output of 'lpstat -t'.

systemctl stop cups-browsed.service

systemctl status cups-browsed.service
● cups-browsed.service - Make remote CUPS printers available locally
   Loaded: loaded (/lib/systemd/system/cups-browsed.service; enabled)
   Active: inactive (dead) since Son 2015-07-26 17:27:01 CEST; 1s ago
  Process: 22426 ExecStart=/usr/sbin/cups-browsed (code=exited, 
status=0/SUCCESS)
 Main PID: 22426 (code=exited, status=0/SUCCESS)

Jul 26 17:27:01 systemd[1]: Stopped Make remote CUPS printers available locally.

LANG=C lpstat -t
scheduler is running
no system default destination
lpstat: No destinations added.
lpstat: No destinations added.
lpstat: No destinations added.
lpstat: No destinations added.

systemctl start cups-browsed.service

LANG=C lpstat -t
scheduler is running
no system default destination
device for HP-LaserJet-1020: ipp://Server1:631/printers/HP_LaserJet_1020
HP-LaserJet-1020 accepting requests since Sun 26 Jul 2015 05:27:42 PM CEST
printer HP-LaserJet-1020 is idle.  enabled since Sun 26 Jul 2015 05:27:42 PM 
CEST

So basically with the browsed.service stopped the broadcasts are ignored?

Let me give you the client's /etc/cups/cups-browsed.conf as well:

grep -v ^& /etc/cups/cups-browsed.conf 

BrowseRemoteProtocols cups
BrowseProtocols cups
BrowseAllow 192.168.1.1
BrowseAllow Server1
BrowsePoll Server1:631
AutoShutdown On

Now, this is interesting:

After I played around with the client's cups-browsed service the printer status 
on the server1 webinterface changed:

Before:
HP LaserJet 1020 HP LaserJet 1020 Foomatic/foo2zjs-z1 (recommended) Idle - 
"Waiting for jobs"

After:
HP LaserJet 1020 HP LaserJet 1020 Foomatic/foo2zjs-z1 (recommended) Idle - 
"Waiting for printer to become available."

And the printer page on the server1 webinterface does always mention:
HP_LaserJet_1020 (Idle, Accepting Jobs, Not Shared)


Any thought's on the matter?

Please CC me with your reply, I forgot to mention I'm no longer subscribed to 
the list.

Regards

Tuxo  

Re: cups/cups-browsed: only advertise online network printers

[Brian]

On Fri 24 Jul 2015 at 15:16:32 +0200, Tuxo Holic wrote:

> I' have a HP LaserJet 1020 USB - plugged to my server running
> debian/stable with cups, the clients connect to it using cups-browsed
> and the cups network protocol.
> The server does *not* run 24/7 nor does my printer: I usually switch
> on the LaserJet as soon as I need it and disable it once I'm done.
> Cups does ignore the fact it is not running: it will advertise the
> printer, clients can see it and start printing jobs already. Once the
> printer comes online, the waiting jobs will be processed all at once.
> Some people might prefer this approach, I'd prefer network printers to
> be invisible on the client side, as long as they are not online. The
> main reason is: this can confuse people and lead to additional
> printing jobs until they realize their mistake of not switching on the
> device.
> Is it possible to limit job handling to *online* printers only on the
> client or on the server side?

Please stop cups-browsed on the client and post the output of 'lpstat -t'.


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cups/cups-browsed: only advertise online network printers

[Tuxo Holic]

Hi list,
I' have a HP LaserJet 1020 USB - plugged to my server running debian/stable 
with cups, the clients connect to it using cups-browsed and the cups network 
protocol.
The server does *not* run 24/7 nor does my printer: I usually switch on the 
LaserJet as soon as I need it and disable it once I'm done. Cups does ignore 
the fact it is not running: it will advertise the printer, clients can see it 
and start printing jobs already. Once the printer comes online, the waiting 
jobs will be processed all at once. Some people might prefer this approach, I'd 
prefer network printers to be invisible on the client side, as long as they are 
not online. The main reason is: this can confuse people and lead to additional 
printing jobs until they realize their mistake of not switching on the device.
Is it possible to limit job handling to *online* printers only on the client or 
on the server side?
Regards,
TuxoHolic