Date: Fri, 4 Sep 1998 17:45:39 -0500 (CDT) From: Jim Dutton <jimd@dutton3.it.siu.edu> To: freebsd-doc@FreeBSD.ORG Subject: New Handbook section suggestion: Advanced Printing - Print Server Message-ID: <199809042245.RAA24130@dutton3.it.siu.edu>
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Most of the necessary set up steps for standalone workstations is
already covered in the Handbook:Printing chapter. In setting up a
(simple) "print server" I found that there wasn't anything explicit
about setting up a "print server", so thought that something along the
following might be of value to new "print managers".
It would be in a new section that explicitly states "print server" and
would (eventually) refer to all of the other pertinent sections.
This is rough draft #1.
=========================================================================
The function of a "print server" is to collect (input) print requests
(jobs), store (enqueue) them somewhere while they are waiting to be
printed, send the print jobs to the desired printer, and possibly do
data transformations on the print data and/or record information for
accounting purposes. Since printers can only print one "job" at a time,
multiple requests for printing must be enqueued somewhere: either on
the local hosts sending print "jobs" or a "print server".
In many cases where a "print server" is established, the server (host) may be
given more disk space than a user workstation, or it may have more disk space
available for printing use (than a user workstation) since it may not have all
of the other applications or data files that a user workstation might have.
For a standalone (Unix) host with a directly attached printer - it, itself, is a
"print server" since the LPD on that standalone host does the input spooling
and output transmission for all print requests. Nothing needs to be done to
define or set up the "print server" since it already exists in the local LPD.
For a standalone (Unix) host connected to a printer via a network interface on
the printer (ie; a "networked printer"), the standalone host may or may not be
"the print server". If the "networked printer" has an LPD function with
spooling capability, then the "networked printer" may be the "print server".
Otherwise, the standalone host will be the "print server" (via its local LDP).
For multiple hosts connected via a network where the printer
is locally attached to a network host, that network host is oftentimes the
"print server", but this is not necessary. Another host could act as the
"print server" (performing the input spooling, printer transmission, and any
input filtering required), sending the final output to the host with the printer
which then sends the data to the printer. The "print host" will spool the data
for each print job, but it will normally be for only one print job at a time.
For multiple hosts connected via a network where the printer is a "networked
printer", either the printer itself will be the "print server" (as mentioned
above), or another network host will be the "print server", depending, mostly,
upon the capabilities of the printer.
In any scenario where the printer itself is a (full fledged) "print server", no
other special configuration needs to be be done (see sections .... about
defining a "networked printer"). Where a host with an attached printer is the
"print server", the same basic rules applly (ie; all "print jobs" are sent to
the "print host" which does the spooling, et cetera).
In the case where a different network host is to be the "print server", a couple
of possible implementations are offered:
1) the "print server" does nothing to the print data other than storing it and
forwarding it on to the print host - no input filter is used or required
2) the "print server" needs to do input filter processing/work (ie; data
transformation from ASCII to Postscript) before sending the print data to a
"networked printer".
============================================================================
Example 1: no input filter on "print server", "print host" with attached
printer and a "default" input filter (note that the user workstation could have
used a different name for its LOCAL print queue name than what is shown)
In this particular instance, the printer is a non-Postscript printer.
[user workstation] --> ["print server"] --> ["print host"] --> [printer]
---------------------
"print host" PRINTCAP
---------------------
##------ HP DeskJet Plus attached to this machine on port 0
##------ DeskJet filters: what's-his-name's package
generic_dphp|Draft Hewlett-Packard DeskJet 500 on Port 0:\
:lp=/dev/lpt0:mx0:\
:sd=/var/spool/lpd:lf=/var/log/lpd-errs:sh:\
:df=/usr/libexec/lpr/djdvipf.sh:\
:cf=/usr/libexec/lpr/djpspf.sh:\
:af=/var/account/lp.printacct:\
:if=/usr/libexec/lpr/djlpf:
#### >>> this is the the default printer:
lp|dhp|ddj|Draft Hewlett-Packard DeskJet (Portrait, 80 Columns):\
:pw#80:\
:pl#63:\
:tc=generic_dphp:
-----------------------
"print server" PRINTCAP
-----------------------
hp|lp:\
:rm=prthost.our.net:rp=dhp:lf=/var/log/lpd-errs:mx0:\
:sd=/var/spool/lpd/hp:af=/var/account/lp.printacct:
-------------------------
user workstation PRINTCAP
-------------------------
hp|lp:\
:rm=prtsrvr.our.net:rp=hp:lf=/var/log/lpd-errs:mx0:
============================================================================
Example 2: ASCII to Postscript input filter on "print server", printer is
"network attached" (has its own, limited, LPD + network card); only simple
accounting is done (no line counts at this point)
The actual printer in this case is an HP5 Postscript. Note the NULL device for
the "print server" lp definition. Without this, the LPD on the "print server"
would not execute the input filter. a2ps was used to do the actual ASCII to
Postscript transformation.
[user workstation] --> ["print server"] --> ["networked" printer]
-----------------------
"print server" PRINTCAP
-----------------------
hplj5sid:\
:rm=hp5si.our.net:rp=hplj5si:af=/var/account/lp.printacct:\
:lf=/var/log/lpd-errs:mx0:rw:
hplj5:\
:lp=/dev/null:af=/var/account/lp.printacct:mx0:\
:lf=/var/log/lpd-errs:\
:if=/usr/local/libexec/hplj5.sh:sd=/var/spool/lpd/hplj5:
-------------------------
user workstation PRINTCAP
-------------------------
hplj5:\
:rm=prtsrvr.our.net:rp=hplj5:af=/var/account/lp.printacct:\
:lf=/var/log/lpd-errs:mx0:sd=/var/spool/lpd/hplj5:
---------------------------
"print server" LP.PRINTACCT
---------------------------
Sep 3 19:00:00 prtsrvr newsyslog[1299]: logfile turned over
VMuser mainframe.our.net Fri Sep 4 11:00:33 CDT 1998
VMuser mainframe.our.net Fri Sep 4 11:04:58 CDT 1998
--------
hplj5.sh
--------
#!/bin/sh
#
today=`date`
#
# save remote user/host in accounting file - no line counting is done
#
result=`echo $5 $7 $today >> $8`
read first_line
length=`echo $first_line | wc -c`
first_two_chars=`expr "$first_line" : '\(..\)'`
#
# PostScript job, print it directly
#
if [ "$first_two_chars" = "%!" ]; then
(echo $first_line && cat && printf "\004") | lpr -h -Phplj5sid && exit 0
exit 2
#
# mainframe print by Lowell - Focus reports - requires Landscape
#
elif [ $5 = "LOWELLW" ]; then
(echo $first_line; cat) | /usr/local/bin/a2ps -1 -ni -nL -v -F7.2| lpr -h -Phplj5sid && exit 0
#
# Plain text, convert it, then print it Landscape
#
elif [ $length -gt 81 ]; then
(echo $first_line; cat) | /usr/local/bin/a2ps -1 -ni -nL -v | lpr -h -Phplj5sid && exit 0
#
# Plain text, convert it, then print it "Stand Up" (Portrait)
#
else
(echo $first_line; cat) | /usr/local/bin/a2ps -1 -p -ni -nL -v | lpr -h -Phplj5sid && exit 0
exit 2
fi
==============================================================================
--
[what I USED to be ...]
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