[Printing-architecture] SLP (Service Location Protocol)

[Michael Sweet]

Till,

On Jul 23, 2014, at 11:02 AM, Till Kamppeter <till.kamppeter at gmail.com> wrote:
> Hi,
> 
> as talked about in the last OP conference call I want to make use of SLP
> to discover printers in the network and especially to discover their
> capabilities. Unfortunately documentation about using SLP, especially
> with Ubuntu Linux, on the internet is sparse.
> 
> I want to let cups-browsed do this automatically, so that I can set up
> driver-less print queues for printers with known languages (PDF,
> PostScript, PCL, ...) but without polling the printer directly to not
> wake up the printer from power save mode.

SLP is a pretty active protocol, even when a Directory Agent is used, so I would be surprised if you'll be able to do discovery without waking up the printer.

> What I would like to know is:
> 
> 1. How do I scan the network for SLP services without knowing service
> names and types and without knowing which hosts in the network provide
> services or are SLP directory agents?

slpd handles the latter for you; you'll want to look for the standard SLP printer service type - the old CUPS code prior to 1.6 mostly did that.

> 2. In a typical SoHo network, are there SLP services or directory
> agents?

No.

> Are the usual SoHo routers directory agents?

No.

> Or do I need to
> to run an SLP server daemon on the local machine to be able to make use
> of SLP?

You don't need one on the local machine, but you *do* need to have one on the network to make SLP practical.

> 3. How can I test my environment with command line tools?

slptool can probably be used to find specific attributes.

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair