Hi, two weeks ago (before the Printing Summit in Lexington) I have observed that faxing with HPLIP 1.6.7, 1.6.9, and 1.6.10 works without problem under Mandriva 2007 (released three weeks ago) and does not work at all with Ubuntu Edgy/6.10 (released last week). Under Ubuntu Dapper/6.06 faxing works, too.
After some discussion with Donald Welch and Phil Thompson we found out that on the transition from PyQt 3.15 to 3.16 a new bug was introduced which broke inter-process communication (IPC) between hpssd and hp-sendfax (a fax job sent into the "hpfax:/..." queue is forwarded to the hp-sendfax of the user who sent the job by hpssd and supposed to stay in the CUPS queue when hp-sendfax is not running in the sender's account). From PyQt 3.16 on Fax jobs sent out by hpssd seem to run into a black hole instead of being picked up by hp-sendfax. Debugging this is very complicated for end users and even experienced system administrators: - It is difficult to find out the version numbers of PyQt and SIP as some distros ship them in the kdebindings package and also if they are in separate packages the package names are not the same. - One cannot easily find out how to bring a Python program into debug logging mode (someome of you told it to me and I saved this information in a file, but whenever I need it I am looking up this file). - Running HPLIP and CUPS normally no footprints of the faxing process appear in any log file. In addition the PyQt guys did not propose any fix or at least a workaround yet. So every Edgy user and also every user trying out KDE 3.5.5 on other distros has broken fax with HPLIP now. To make faxing with HPLIP more robust and to make admin's life easier, I suggest the passing of the fax via hot folder: Every user has a hot folder named ~/hpfax/ in his home directory (auto-created if needed). When a user sends a job into the fax queue, the hpijs driver converts the job into fax G3 format and the hpfax CUPS backend drops the fax G3 file in the user's hot folder (hot folder created by hpfax backend if needed). hpfax should be fairly the same code as the cups-pdf backend available as free software here (and available as Debian package in Ubuntu Edgy): http://www.physik.uni-wuerzburg.de/~vrbehr/cups-pdf/ On Ubuntu Edgy (CUPS runs as "cupsys" user) this backend runs SUID root so that it has root rights to create directories and files in the user's home directory. On other distros (CUPS runs as root) it is enough to give 0700 permissions to the backend. As soon as the user runs hp-sendfax, hp-sendfax checks the hot folder regularly (for example every 3 sec) and shows every file in the list of files to be faxed, but does not delete or modify any file in the hot folder. If the user uses the "add to list" function, the chosen file is simply put into the fax queue and the converted file appears automatically in the list as soon as CUPS has converted it and the hpfax backend has dropped the result in the hot folder. If the user finally sends his fax, every successfully faxed file gets deleted from the hot folder. If the user closes hp-sendfax without faxing, the files stay in the hot folder and can be faxed by calling hp-sendfax later. Advantages: - CUPS queue for faxing is not blocked when the user who has sent the first job has no hp-sendfax running, as fax jobs leave the CUPS queue immediately. - CUPS's filter work to get a job converted to G3 can easily be monitored by watching files appearing in the hot folder and by opening them with Konqueror (Konqueror uses KDE's fax program to display G3 files). - hp-sendfax can be started before or after sending the fax job, nothing gets lost due to hp-sendfax not running. - hp-sendfax can be closed without faxing and the fax jobs do not get lost. They can be faxed later. - The data flow is much more clear to users and admins, so debugging is easier. Also maintaining it secure is probably easier then. WDYT about that? Till ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ HPLIP-Devel mailing list HPLIP-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/hplip-devel
