[sane-devel] Fwd: Ricoh SP204SN AIO network scanner

Louis Lagendijk louis at fazant.net
Mon Mar 2 18:49:47 GMT 2020

On Mon, 2020-03-02 at 15:24 +0300, Alexander Pevzner wrote:
> > I'd like this kind of discovery be added to saned, the sane daemon.
> The only thing saned actually does is exporting local scanner into
> network.
> It actually would be much better to reorganize SANE around some
> daemon, 
> which will:
>    1) Perform discovery in background and handle PnP
>    2) Provide enough privileges for USB access
>    3) Provide interlocking between SANE-capable applications, that
> runs 
> in the same time.
I recall that there are multi-functionals that allow EITHER printer or
scanner access, but not both at the same time. 
Early detection of devices and their capabilities would be ok, but
initialization would anyhow have to wait untill the device is to be
used. The device would need to be released as soon as scanning is done.
So the time gains would be limited.

> I think, architecture should be the following:
>    1) Daemon loads all necessary backends, based on dynamic 
> discovery/configuration (like sane-dll does it now), and does it
> early, 
> so when users want to scan, everything already initialized and there
> is 
> no annoying delay on startup
See above, this may not be feasible 

>    2) Daemon exposes scanners using some kind of IPC
>    3) There is one additional backend needs to be written, intended
> to 
> be loaded directly by applications - it's responsibility is to 
> communicate with daemon as a client, using daemon's IPC
What is different compared to the net backend?
Such a daemon would mean additional resources would be required
(memory) and an additional attack surface.
How do you deal with hardware attached/ removed after the initial scan?

This can of course all be solved, but I am not so sure of the benefits.
I like the Sane , but be aware:

BR, Louis

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