PAPI Client Commands

PAPI Client Commands

Delivered in Solaris Nevada build 44

What are they ?

 Since their beginning, the printing commands have been tied to a specific print system because they have been implemented on top of print system specific protocols and interfaces. This is true of BSD 4.x LPR, SysV LP, LPRng, CUPS, and more. With the recent introduction of the FSG OpenPrinting Open Standard Print (PAPI), it is now possible to move these commands on top of a print service/protocol neutral interface. Currently, the PAPI include enough functionality to support replacement of the following commands:

Destination Names

Each of the printing commands listed above takes a printer/queue/destination name as at least one of it's arguments.  These destination names can be specified in one of three forms:

 Printer URI formats currently supported include the following:

Some additional information

• As a result of layering these changes, the following commands will no longer need to be installed SUID root:

/usr/bin/lp, /usr/bin/lpstat, /usr/bin/cancel, /usr/bin/lpmove,
 /usr/{ucb|bin}/lpr, /usr/{ucb|bin}lpq, /usr/{ucb|bin}/lprm,
 /usr/lib/print/printd.

In the past, they were installed SUID root because they needed some elevated privilege to either open a reserved port,  allocate a sequential job-id number, or maniplate files in /var/spool/print.  Since this functionality has been localized into a small "helper" application (/usr/lib/print/lpd-port), applications using RFC1179 based PAPI support no longer need elevated privilege.  lpd-port contains minimal support for passing RFC1179 protocol requests on a reserved port and allocating sequential job-id numbers.  While it is installed SUID root, it temporarily drops all elevated privilege until the moment that they are needed.  When needed, the privilege is elevated for the required operation and perminently dropped if it is no longer required.  On Solaris, this is done through the use of privileges(5).  On other platforms, this is done using setuid/seteuid/setreuid().

• If you have a local printer and don't want to share it with anyone on the network, you can now safely disable the printing network listeners

# svcadm disable application/print/ipp-listener \
                             application/print/rfc1179 (lpd-listener)

• If you have a Solaris 9u6 or later server, or a CUPS server, lpstat will provide you with more information about remote print queues (and jobs), as well as their capabilities when you use IPP to talk to those servers.
• It is now possible to accept, reject, enable and disable remote print queues with proper authorization when IPP is in use (more on this to follow)
• It is now possible to remotely move jobs between queues on a print server when IPP is in use.
• It is now possible to modify your print jobs remotely when IPP is in use. (eg. submit your job held, change the number of copies, turn on duplexing and release it for printing)

Where can I get access to the bits ?

Where is the Code ?

Currently, the project is housed on SourceForge at http://sf.net/projects/openprinting/ The code contained in the SourceForge project includes a complete implementation of the PAPI with support for interaction with RFC-1179 based print services, as well as IPP based print services. Also included in that code base is and Apache module that implements server side support for IPP on top of the PAPI. The OpenSolaris code base contains PAPI support for local LP interaction. Though much of the work in the SourceForge project is already delivered with Solaris, this project is focusing on delivering the client commands support already in the code base as replacements for the current implementations that are tied directly to either lpsched or the rfc-1179 protocol.

How can I get Involved ?

The OpenPrinting project, currently hosted at SourceForge (http://sf.net/projects/openprinting/), is where implementation work is being done for the PAPI.  If you are interested in support for other print systems, or extending the API, that is probably a good place to start.  Any work to extend the API will at least be prototyped there before rolling it back into the PAPI standard.
 You will also find pre-built RPM and dpkg(.deb) packages for Linux systems that and be installed in /opt/papi on a Linux system.  Since the naming support native to Solaris is emulated on the Linux systems, it's not as complete as what's available on Solaris.  However, it does contain files and NIS support for printing configuration lookup.
 If you run some other OS, you should be able to build the code with little or no effort.  For the most part, the code makes use of POSIX interfaces.  The only significant exception is in the RFC1179 support, were there is code to pass file
 descriptors between processes (child to parent).  The code to do so is ifdef'd with support for SysV, BSD 4.3, and BSD 4.4 (also Linux) methods of doing this.