On Wed, 2019-11-13 at 09:48 +0100, Johannes Meixner wrote: > Hello, > > On Nov 12 18:06 Olaf Meeuwissen wrote (excerpt): > > > > #130: https://gitlab.com/sane-project/backends/issues/130 > > #141: https://gitlab.com/sane-project/backends/issues/141 > > I agree with the initial reporters that the usually expected > meaning of 'local' is in particular 'not via network'. > > Therefore the special case that a scanner with a network interface > that is directly connected by a network cable to a dedicated > network interface on the computer where SANE runs > is not a local scanner regardless that the scanner is directly > attached with a cable to the computer where SANE runs. > > > > Discussing what `sane_get_devices()` should be considered > `local_only`, > > we are no longer sure what is and is not local :-o > ... > >> FWIW, the SANE Standard, in section 4.3.3 sane_get_devices, has > the > >> following to say: > ... > >> ... If argument > >> `local_only` is true, only local devices are returned (devices > >> directly attached to the machine that SANE is running on). > > I think the word 'attached' has the implicit meaning that > a connection method is used where usually a cable is used > and not only electromagnetic waves like for Bluetooth > or any other connection method that is usually wireless. > > Therefore the special case that a USB cable is replaced > with a pair of USB-thingies that replace the USB cable with > a wireless connection is still 'directly attached'. > > > I think the terms 'local' and 'directly attached' are > technically vague and should be replaced with technically > more precise terms. > > In this case I think the connection type is what should make > the difference so that the sane_get_devices() documentation > should be more explanatory and more precise for example like: > ------------------------------------------------------------------ > If argument 'local_only' is true, only local devices are returned. > > Local devices are those that are directly attached to the machine > that SANE is running on. > > Directly attached means that a connection method is used > where usually a direct cable connection is used and > that is in general not a network connection. > > The following connection methods are 'directly attached': > > USB > parallel port > SCSI > > All other connection methods are not 'directly attached'. > > Accordingly if argument 'local_only' is true, only devices are > returned that are connected via USB or parallel port or SCSI. > ------------------------------------------------------------------ > Of course that could be simplified to: > ------------------------------------------------------------------ > If argument 'local_only' is true, only devices are returned > that are connected to the machine that SANE is running on > via USB or parallel port or SCSI. > ------------------------------------------------------------------ > But then is does no longer explain the reasoning behind > so things may again break apart when a new connection method > gets supported by SANE (e.g. Tap-proof Wired Bluetooth ;-) > Aren't there scanners/AIOs for Mac that use Thunderbolt? > > > FWIW, > cf. https://en.opensuse.org/YaST_Printer > that reads (excerpt): > ------------------------------------------------------------------ > There is a difference between "local/remote queue" > and "local/remote printer": > > "Local queue" means a print queue which is configured on the > local computer (strictly speaking the computer where the YaST > printer module runs) which is usually the computer where the > user sits in front of. > > "Remote queue" means a print queue which exists on whatever > computer in the network or on whatever network printer. > > > "Local printer" means a printer device which is directly connected > to the local computer (usually a USB printer). > > "Remote printer" means a printer device which is not directly > connected to the local computer (usually a printer with a > built-in network interface). > ------------------------------------------------------------------ > > Accordingly a printer with a built-in network interface that is > directly connected by a network cable to a dedicated network > interface on the computer is not a local printer and > a USB printer where the usual USB cable is replaced by > whatever wireless technique (that may even reach out > into the next building) is still a local printer. > > I like Johannes's explanation. I now implemented the local_only support in the pixma backend. @Olaf: CI/CD seems to be broken, can you please have a look? I don't think that my changes are to be blamed, but I may have done something silly. The pipeline fails with:
175 $ ./tools/create-changelog.sh 176 $ ./tools/update-upstreams.sh 180 ERROR: Job failed: exit code 1 Thanks, Louis
