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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
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<h1 class="SECT1"><a name="AEN5207">11.8. Problems With
Network Print Servers</a></h1>
<p>Most of the Network Print Servers are implemented using
extremely simply software. The following is a list of some
problems and what options the <b class=
"APPLICATION">LPRng</b> software uses to handle them.</p>
<div class="SECT2">
<h2 class="SECT2"><a name="AEN5211">11.8.1. Network Print
Server Not Responding</a></h2>
<p>Only a single TCP/IP connection is accepted at a time.
This means that when one user is sending a job then the
unit will not accept other connections. There is another
side effect of this problem, which is that some
implementations will accept a network connection but not
read any data from the connection until the previous
connection is finished.</p>
<p>The deal with these problems the <var class=
"LITERAL">connect_timeout</var>, <var class=
"LITERAL">send_job_rw_timeout</var>, and <var class=
"LITERAL">send_query_rw_timeout</var> are used to control
job transfer and lpq status gathering. See <a href=
"printingjob.htm">Printing Job Files</a> and <a href=
"opendevice.htm">Opening the Output Device</a> for
details.</p>
</div>
<div class="SECT2">
<h2 class="SECT2"><a name="AEN5220">11.8.2. Network Print
Server Does Not Handle LPQ, LPRM</a></h2>
<p>Some Network Print Servers do not respond to <var class=
"LITERAL">lpq</var> or <var class="LITERAL">lprm</var>
queries correctly. The <var class=
"LITERAL">remote_support</var> option can be used to solve
this problem by specifying what operations the remote print
server can handle:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5226"></a>
<pre class="SCREEN">
:remote_support=RMQVC
R = lpr, M = lprmg, Q = lpq, V = lpq -v, C = lpc
:remote_support=R # printer only handles LPR
</pre>
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<br>
<br>
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<div class="SECT2">
<h2 class="SECT2"><a name="AEN5228">11.8.3. Incomplete Job
Transfers</a></h2>
<p>This is the result of a defective or buggy TCP/IP
stacks. A common problem is the habit that some Network
Print Servers occaisionally discard data at the end of a
print job when a network connection is <span class=
"emphasis"><i class="EMPHASIS">half-closed</i></span>. A
<span class="emphasis"><i class=
"EMPHASIS">half-closed</i></span> connection is one where
one end of the sending connection indicates that no further
data will be sent. Unfortunately, the Network Print Server
will then try to close the connection in the other
direction. When this does not immediately succeed, it will
terminate the network connection, discarding any unprinted
data.</p>
<p>The <var class="LITERAL">half_close</var> flag can be
used to solve this problem. See <a href=
"normalterm.htm">Normal Termination</a> for more
details.</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5236"></a>
<pre class="SCREEN">
lp:lp=lp@remote # shutdown(fd,WRITE) connection, wait for end
lp:lp=lp@remote:half_close@ # close() connection and do not wait
</pre>
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