1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2 3<html> 4 <head> 5 <meta name="generator" content="HTML Tidy, see www.w3.org"> 6 <title>Problems With Network Print Servers</title> 7 <meta name="GENERATOR" content= 8 "Modular DocBook HTML Stylesheet Version 1.7"> 9 <link rel="HOME" title=" LPRng Reference Manual" href= 10 "index.htm"> 11 <link rel="UP" title="Printer Communication and Protocols " 12 href="printercomm.htm"> 13 <link rel="PREVIOUS" title="HP JetDirect Interface" href= 14 "x5157.htm"> 15 <link rel="NEXT" title="Printing to a SMB (MicroSoft) Printer" 16 href="x5224.htm"> 17 </head> 18 19 <body class="SECT1" bgcolor="#FFFFFF" text="#000000" link= 20 "#0000FF" vlink="#840084" alink="#0000FF"> 21 <div class="NAVHEADER"> 22 <table summary="Header navigation table" width="100%" border= 23 "0" cellpadding="0" cellspacing="0"> 24 <tr> 25 <th colspan="3" align="center">LPRng Reference Manual: 5 26 Sep 2003 (For LPRng-3.8.22)</th> 27 </tr> 28 29 <tr> 30 <td width="10%" align="left" valign="bottom"><a href= 31 "x5157.htm" accesskey="P">Prev</a></td> 32 33 <td width="80%" align="center" valign="bottom">Chapter 34 11. Printer Communication and Protocols</td> 35 36 <td width="10%" align="right" valign="bottom"><a href= 37 "x5224.htm" accesskey="N">Next</a></td> 38 </tr> 39 </table> 40 <hr align="LEFT" width="100%"> 41 </div> 42 43 <div class="SECT1"> 44 <h1 class="SECT1"><a name="AEN5193">11.8. Problems With 45 Network Print Servers</a></h1> 46 47 <p>Most of the Network Print Servers are implemented using 48 extremely simply software. The following is a list of some 49 problems and what options the <b class= 50 "APPLICATION">LPRng</b> software uses to handle them.</p> 51 52 <div class="SECT2"> 53 <h2 class="SECT2"><a name="AEN5197">11.8.1. Network Print 54 Server Not Responding</a></h2> 55 56 <p>Only a single TCP/IP connection is accepted at a time. 57 This means that when one user is sending a job then the 58 unit will not accept other connections. There is another 59 side effect of this problem, which is that some 60 implementations will accept a network connection but not 61 read any data from the connection until the previous 62 connection is finished.</p> 63 64 <p>The deal with these problems the <var class= 65 "LITERAL">connect_timeout</var>, <var class= 66 "LITERAL">send_job_rw_timeout</var>, and <var class= 67 "LITERAL">send_query_rw_timeout</var> are used to control 68 job transfer and lpq status gathering. See <a href= 69 "printingjob.htm">Printing Job Files</a> and <a href= 70 "opendevice.htm">Opening the Output Device</a> for 71 details.</p> 72 </div> 73 74 <div class="SECT2"> 75 <h2 class="SECT2"><a name="AEN5206">11.8.2. Network Print 76 Server Does Not Handle LPQ, LPRM</a></h2> 77 78 <p>Some Network Print Servers do not respond to <var class= 79 "LITERAL">lpq</var> or <var class="LITERAL">lprm</var> 80 queries correctly. The <var class= 81 "LITERAL">remote_support</var> option can be used to solve 82 this problem by specifying what operations the remote print 83 server can handle:</p> 84 85 <div class="INFORMALEXAMPLE"> 86 <a name="AEN5212"></a> 87<pre class="SCREEN"> 88 :remote_support=RMQVC 89 R = lpr, M = lprmg, Q = lpq, V = lpq -v, C = lpc 90 :remote_support=R # printer only handles LPR 91</pre> 92 </div> 93 <br> 94 <br> 95 </div> 96 97 <div class="SECT2"> 98 <h2 class="SECT2"><a name="AEN5214">11.8.3. Incomplete Job 99 Transfers</a></h2> 100 101 <p>This is the result of a defective or buggy TCP/IP 102 stacks. A common problem is the habit that some Network 103 Print Servers occaisionally discard data at the end of a 104 print job when a network connection is <span class= 105 "emphasis"><i class="EMPHASIS">half-closed</i></span>. A 106 <span class="emphasis"><i class= 107 "EMPHASIS">half-closed</i></span> connection is one where 108 one end of the sending connection indicates that no further 109 data will be sent. Unfortunately, the Network Print Server 110 will then try to close the connection in the other 111 direction. When this does not immediately succeed, it will 112 terminate the network connection, discarding any unprinted 113 data.</p> 114 115 <p>The <var class="LITERAL">half_close</var> flag can be 116 used to solve this problem. See <a href= 117 "normalterm.htm">Normal Termination</a> for more 118 details.</p> 119 120 <div class="INFORMALEXAMPLE"> 121 <a name="AEN5222"></a> 122<pre class="SCREEN"> 123 lp:lp=lp@remote # shutdown(fd,WRITE) connection, wait for end 124 lp:lp=lp@remote:half_close@ # close() connection and do not wait 125</pre> 126 </div> 127 <br> 128 <br> 129 </div> 130 </div> 131 132 <div class="NAVFOOTER"> 133 <hr align="LEFT" width="100%"> 134 135 <table summary="Footer navigation table" width="100%" border= 136 "0" cellpadding="0" cellspacing="0"> 137 <tr> 138 <td width="33%" align="left" valign="top"><a href= 139 "x5157.htm" accesskey="P">Prev</a></td> 140 141 <td width="34%" align="center" valign="top"><a href= 142 "index.htm" accesskey="H">Home</a></td> 143 144 <td width="33%" align="right" valign="top"><a href= 145 "x5224.htm" accesskey="N">Next</a></td> 146 </tr> 147 148 <tr> 149 <td width="33%" align="left" valign="top">HP JetDirect 150 Interface</td> 151 152 <td width="34%" align="center" valign="top"><a href= 153 "printercomm.htm" accesskey="U">Up</a></td> 154 155 <td width="33%" align="right" valign="top">Printing to a 156 SMB (MicroSoft) Printer</td> 157 </tr> 158 </table> 159 </div> 160 </body> 161</html> 162 163