[cups] CUPS application in Cloud

[Toerless Eckert]

Michael,

Is there any doc explaining what "cloud" function this
ippsample project is implementing ? Or am i down to RTFS ?

Rashi,

Unless i am overlooking something, all the openly documented
printing options on printers like IPP are based on printers
waiting to receive connections from print software, but not
the other way around. Thats the main issue for cloud
printing.

One option is then to have a strict firewall close to the printer
supporting connections only from a well-known cloud-sever
IP-address. And if your cloud-server changes IP address
you'll run into a nightmare changing those firewalls. Or you
find firewalls capable of DNS-name based firewall rules and
hope your cloud service DNS-name can stay constant and is
not attackable.  And you also would need to know the IP-addresses
of the printers, which may not be permanent either, but you
could not pass DNS-SD easily through this setup.

The VPN option Michael mentioned is a way to solve the
problem, but if you have to rely on VPN equipment/configuration
that you do not configure yourself, its going to be a similar 
nightmare as firewall rules - you have to tell someone else what
to set up, and its likely not working. And if the printers use
dynamic IP addresses that may change over time, you need
mDNS proxying to learn their IP addresses in the cloud. 

I think its hard to find an easily administrable solution
without dropping some box local to the printer (same LAN).
What that box should do is subject to a couple considerations.
It could simply be a VPN client box configured to proxy also
mDNS, but then you need to send through the WAN the rasterfiles
for the printer. If the printer renders itself, this will
be "fine", otherwise these could be huge and you
may want to have the local box do rendering (aka: run cups
on the box). Does not have to be as fast as a cloud-server
could render.  Just faster than the printer.

If you go with the printer vendors cloud print solutions
(or similarily google cloud print) you will likely more
easily solve issues, but then those vendors
know all your printed files because your files will go
through their servers. Not much an issue if you
already trust similar documents to their cloud storage
or similar services though. AFAIK, none of these services
are documented and allow for the printers cloud print support
functions to connect to an alternate cloud server like yours
(or mine). I wish i was wrong. 

Toerless

On Mon, Mar 26, 2018 at 09:22:47AM -0400, Michael Sweet wrote:
> I should also note that IPP does provide cloud extensions to properly support this kind of architecture - prototyping is happening in the "ippsample" project here:
> 
>     https://github.com/istopwg/ippsample
> 
> although this is nothing I would use for production yet...
> 
> 
> > On Mar 26, 2018, at 9:17 AM, Michael Sweet <msweet at apple.com> wrote:
> > 
> > Rasha,
> > 
> >> On Mar 26, 2018, at 3:45 AM, Sonthalia, Rashi <rashi.sonthalia at mheducation.com> wrote:
> >> 
> >> Hi,
> >> 
> >> 
> >> We are currently using CUPS version 1.1.21 software and our requirement is to move it to cloud. Could you please let us know if it is possible with the current version or an upgrade to other version of the CUPS software  is required?
> > 
> > First, CUPS 1.1.21 is ancient (14 years old) and unsupported.  Any Linux cloud solution will run a more recent version...
> > 
> > Second, the issue you will run into is remote access to your printers - generally speaking you *don't* want to make your printers accessible over the Internet...  Some people use VPN tunnels, although you'll need to ask in another forum for help with that... :)
> > 
> > _________________________________________________________
> > Michael Sweet, Senior Printing System Engineer
> > 
> 
> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer
> 
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