Hello, perhaps it is a stupid question but I do not well understand why HPLIP requires continuously running processes (i.e. daemons).
The underlying problem of my question is that because of the daemons it is complicated to update HPLIP in a running system. The correct way to update HPLIP is: /etc/init.d/cups stop /etc/init.d/hplip stop replace the installed HPLIP files with the files of the new version /etc/init.d/hplip start /etc/init.d/cups start It is not possible to stop and start the services in an automated way (e.g. via RPM preinstall and postinstall scripts) because it is not possible to stop (and re-start) the whole printing service in an automated way when only one single printer driver package is to be updated because all currently printing jobs would be interrupted and re-printed from the very beginning which is not possible in particular in the business environment. Therefore I think about what the inevitable reason is which requires continuously running processes but up to now I didn't find such a reason. My thoughts up to now: 1) Mutual exclusion: Mutual exclusion is needed when different users or processes try to access a device at the same time (e.g. one user prints while a second user wants to scan while a third user queries the device status). I think a usual lock file which contains device status info should be sufficient so that the other users can be informed if and why the device is currently in use. 2) Track the device status: Why continuously track the device status when no user or process asks for it? Shouldn't it be sufficient to query the device status from the lock file (if another process is currently accessing the device) or if no such file exists query it anew directly from the device? 3) Access permissions: Daemons which run as root seem to solve any access permission problem but actually they ignore any access permission policy. If there were no "root"-daemons, the established access permission policies of each Linux distribution could be used even for HPLIP. Kind Regards Johannes Meixner -- SUSE LINUX Products GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany AG Nuernberg, HRB 16746, GF: Markus Rex ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ HPLIP-Devel mailing list HPLIP-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/hplip-devel
