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<th colspan="3" align="center">LPRng Reference Manual: 24
Sep 2004 (For LPRng-3.8.28)</th>
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<td width="80%" align="center" valign="bottom">Chapter
19. RFC 1179 - Line Printer Daemon Protocol</td>
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<h1 class="SECT1"><a name="JOBTRANSFER">19.3. Job
Transfer</a></h1>
<p>Options used:</p>
<ul>
<li>
<p><var class="LITERAL">longnumber</var> FLAG <span
class="emphasis"><i class="EMPHASIS">Long job number (6
digits)</i></span></p>
</li>
<li>
<p><var class="LITERAL">send_data_first</var> FLAG <span
class="emphasis"><i class="EMPHASIS">Send data files
first</i></span></p>
</li>
<li>
<p><var class="LITERAL">use_shorthost</var><span class=
"emphasis"><i class="EMPHASIS">Use short
hostname</i></span></p>
</li>
</ul>
<br>
<br>
<p>A job transfer operation starts with a job transfer
request, followed by several file transfer operations. At the
end of the file transfers, the connection should be
closed.</p>
<p>A file transfer request has the form:</p>
<div class="INFORMALTABLE">
<a name="AEN10199"></a>
<table border="1" frame="border" rules="all" class=
"CALSTABLE">
<col>
<col>
<thead>
<tr>
<th>Command</th>
<th>Purpose</th>
</tr>
</thead>
<tbody>
<tr>
<td>\001\n</td>
<td>abort</td>
</tr>
<tr>
<td>\002nnnn cfname</td>
<td>control file transfer</td>
</tr>
<tr>
<td>\003nnnn dfname</td>
<td>data file transfer</td>
</tr>
</tbody>
</table>
</div>
<br>
<br>
<p>The abort operation is used to terminate job transfer and
indicate that the job should not be processed for printing.
The connection will be closed and the partly transferred job
will be discarded.</p>
<p>The control file and data file transfer commands have a
length (in bytes) of the file and the name of the file to be
transferred. When the command is received, the server will
reply with a status line:</p>
<div class="INFORMALTABLE">
<a name="AEN10217"></a>
<table border="1" frame="border" rules="all" class=
"CALSTABLE">
<col>
<col>
<thead>
<tr>
<th>Status</th>
<th>Purpose</th>
</tr>
</thead>
<tbody>
<tr>
<td>\000</td>
<td>Accepted, proceed</td>
</tr>
<tr>
<td>\nnn</td>
<td>Rejected with error code</td>
</tr>
</tbody>
</table>
</div>
<br>
<br>
<p>The reply is only a single octet. Some defective
implementations of RFC1179 send a LF after the octet, which
makes life very difficult. <b class="APPLICATION">LPRng</b>
makes an effort to detect these non-conforming RFC1179
systems and will accept jobs from them. However, it will not
send jobs to them.</p>
<p>If <b class="APPLICATION">LPRng</b> sends a reject code,
as an extension to RFC1179 it also sends an error message.
Note that the values for error codes are not defined, nor are
their causes. <b class="APPLICATION">LPRng</b> uses the
following values for error codes, which appear to be
compatible with many, but not all, of the BSD <b class=
"APPLICATION">lpd</b> based systems:</p>
<div class="INFORMALTABLE">
<a name="AEN10236"></a>
<table border="1" frame="border" rules="all" class=
"CALSTABLE">
<col>
<col>
<thead>
<tr>
<th>Code</th>
<th>Error</th>
</tr>
</thead>
<tbody>
<tr>
<td>\000</td>
<td>Accepted, proceed</td>
</tr>
<tr>
<td>\001</td>
<td>Queue not accepting jobs</td>
</tr>
<tr>
<td>\002</td>
<td>Queue temporarily full, retry later</td>
</tr>
<tr>
<td>\003</td>
<td>Bad job format, do not retry</td>
</tr>
</tbody>
</table>
</div>
<br>
<br>
<p>When the sender gets the reply indicating success, it
sends the <var class="LITERAL">nnnn</var> bytes of the
control or data file, followed by a <var class=
"LITERAL">\000</var> octet. The receiver will then reply as
above; a single <var class="LITERAL">\000</var> octet
indicating success.</p>
<p>The above procedure is carried out until all data files
and the control file of a job are transferred.</p>
<p>RFC1179 is silent on the following issues:</p>
<ol type="1">
<li>
<p>When sending a job, do you send the control file
first, followed by the data file(s), or the data files
first?</p>
</li>
<li>
<p>When sending multiple jobs, can you send them on a
single connection, or do you have to establish a new
connection for each job?</p>
</li>
</ol>
<br>
<br>
<p><b class="APPLICATION">LPRng</b> will <span class=
"emphasis"><i class="EMPHASIS">accept</i></span> jobs whether
they are sent control or data files first. By default, it
sends the control file first, followed by the data file. If
the destination system requires that the data files be sent
first, the <var class="LITERAL">send_data_first</var>
printcap option can be used to force data files to be sent
first.</p>
<p>RFC1179 states that: <a name="AEN10271"></a></p>
<blockquote class="BLOCKQUOTE">
<p>The name of the control file ... should start with ASCII
"cfA", followed by a three digit job number, followed by
the host name which has constructed the control file.</p>
</blockquote>
<br>
<br>
<p>The <span class="emphasis"><i class=
"EMPHASIS">should</i></span> in this wording indicates that
this is simply a guideline, and that other formats are
possible. Some of the major problems with this format are as
follows:</p>
<ol type="1">
<li>
<p>The restriction to 3 digits means that at most 1000
jobs can be in a queue. Strangely, some systems generate
far more than 1000 jobs a day, and need to archive them
on a regular basis. The <var class=
"LITERAL">longnumber</var> option will allow <b class=
"APPLICATION">LPRng</b> to use a 6 digit job number for
files in the print queue.</p>
</li>
<li>
<p>The host name format is not specified. Some
implementations consider that this is the short host
name, while others think it is the fully qualified domain
name (FQDN). <b class="APPLICATION">LPRng</b>, by
default, will use the FQDN host name. However, the <var
class="LITERAL">use_shorthost</var> option will force it
to use short host names in control and data files.</p>
</li>
<li>
<p>The <var class="LITERAL">cfA</var> control file name
was modified to allow the job priority to be used as the
A letter of the control file. By default, this is A
(lowest, i.e. <var class="LITERAL">cfA</var>) and but can
range to Z (highest, i.e. <var class=
"LITERAL">cfZ</var>). All known spoolers except <b class=
"APPLICATION">LPRng</b> seem to ignore the actual value
of the letter.</p>
</li>
</ol>
<br>
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