460 lines
14 KiB
HTML
460 lines
14 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>Read from Virtual Terminal (QTVRDVT) API</title>
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<!-- Begin Header Records ========================================== -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>Read from Virtual Terminal (QTVRDVT) API</h2>
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<div class="box" style="width: 70%;">
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<br>
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Required Parameter Group:<br>
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<!-- iddvc RMBR -->
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<br>
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<table width="100%">
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<tr>
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<td align="center" valign="top" width="10%">1</td>
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<td align="left" valign="top" width="50%">Virtual terminal handle</td>
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<td align="left" valign="top" width="20%">Input</td>
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<td align="left" valign="top" width="20%">Char(16)</td>
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</tr>
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<tr>
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<td align="center" valign="top">2</td>
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<td align="left" valign="top">Read information</td>
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<td align="left" valign="top">Output</td>
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<td align="left" valign="top">Char(10)</td>
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</tr>
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<tr>
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<td align="center" valign="top">3</td>
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<td align="left" valign="top">Data buffer</td>
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<td align="left" valign="top">Output</td>
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<td align="left" valign="top">Char(*)</td>
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</tr>
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<tr>
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<td align="center" valign="top">4</td>
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<td align="left" valign="top">Number of bytes to read</td>
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<td align="left" valign="top">Input</td>
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<td align="left" valign="top">Binary(4)</td>
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</tr>
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<tr>
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<td align="center" valign="top">5</td>
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<td align="left" valign="top">Data received</td>
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<td align="left" valign="top">Output</td>
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<td align="left" valign="top">Binary(4)</td>
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</tr>
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<tr>
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<td align="center" valign="top">6</td>
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<td align="left" valign="top">Error code</td>
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<td align="left" valign="top">I/O</td>
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<td align="left" valign="top">Char(*)</td>
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</tr>
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</table>
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: No<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The Read from Virtual Terminal (QTVRDVT) API reads data from the virtual
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terminal into the server program's data buffer. Your application should read
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data only if it has received an asynchronous notification message on the data
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queue, or if the more data flag was set on a previous read operation. The data
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received is in 5250 data stream format.</p>
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<p>Only one full-screen display of data can be received at a time. If the data
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buffer is too small, partial displays are received and the more data flag for
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the QTVRDVT API's read information parameter is set to 1.</p>
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<p>Before working with 5250 data streams, be sure to see the <cite>
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IBM 5494 Functions Reference</cite> book, SC30-3533. This book can be viewed online
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through the
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<a href="http://www.elink.ibmlink.ibm.com/public/applications/publications/cgibin/pbi.cgi?CTY=US" target="_blank">IBM
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Publications Center</a><img src="www.gif" alt="Link outside Information Center">.</p>
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<br>
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<h3>Authorities and Locks</h3>
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<p>None.</p>
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<br>
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<h3>Required Parameter Group</h3>
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<dl>
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<dt><strong>Virtual terminal handle</strong></dt>
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<dd>INPUT; CHAR(16)
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<p>The reference code for the open virtual terminal path, created by the
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operating system with the Open Virtual Terminal Path (QTVOPNVT) API.</p>
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</dd>
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<dt><strong>Read information</strong></dt>
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<dd>OUTPUT; CHAR(10)
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<p>Information about the read operation. The characters and their meanings
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are:</p>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top" width="5%"><em>1</em></td>
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<td align="left" valign="top" width="95%">The operation code, which gives the
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server program additional information about i5/OS status and what is expected
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of the server program. Valid values for this parameter are:
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<table cellpadding="5">
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<tr>
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<td align="left" valign="top"><em>1</em></td>
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<td align="left" valign="top">Invite</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>2</em></td>
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<td align="left" valign="top">Output only</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>3</em></td>
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<td align="left" valign="top">Put/get</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>4</em></td>
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<td align="left" valign="top">Save display</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>5</em></td>
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<td align="left" valign="top">Restore display</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>6</em></td>
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<td align="left" valign="top">Read immediate</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>8</em></td>
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<td align="left" valign="top">Read display</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>A</em></td>
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<td align="left" valign="top">Cancel invite</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>B</em></td>
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<td align="left" valign="top">Turn on message light</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>C</em></td>
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<td align="left" valign="top">Turn off message light</td>
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</tr>
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</table>
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<p>For detailed descriptions of these codes, see <a href="#HDROPCD">Read Operation Codes</a>.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>2</em></td>
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<td align="left" valign="top">More data flag. Valid values for this parameter
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are:
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<table cellpadding="5">
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top">There is no more data.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>1</em></td>
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<td align="left" valign="top">More data is available. Issue the read operation
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again to receive the additional data. This flag is set if the buffer specified
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on input is not large enough to hold all of the data received from the virtual
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terminal.</td>
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</tr>
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</table>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>3</em></td>
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<td align="left" valign="top">Key flag. Valid character values for this
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parameter are:
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<table cellpadding="5">
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top">The Enter key was pressed.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>1</em></td>
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<td align="left" valign="top">The System Request key was pressed.</td>
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</tr>
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</table>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>4-10</em></td>
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<td align="left" valign="top">Reserved. These characters must be blank.</td>
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</tr>
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</table>
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<br>
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</dd>
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<dt><strong>Data buffer</strong></dt>
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<dd>OUTPUT; CHAR(*)
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<p>The server program's buffer for receiving data from the virtual terminal.
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The data is a 5250 data stream.</p>
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<p>The QTVRDVT API does not lock the data buffer. Thus, other applications
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should not use the buffer while the API is using it.</p>
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<p>The data buffer should be large enough to hold the largest display of data
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expected. If it is not large enough for all the data to fit, the more data flag
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of the read information parameter is set to 1. Additional read requests must be
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performed, until all the remaining data is received and the more data flag is
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set back to 0.</p>
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</dd>
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<dt><strong>Number of bytes to read</strong></dt>
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<dd>INPUT; BINARY(4)
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<p>The number of bytes to read from the data buffer. This number must be
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smaller than or equal to the size of the data buffer.</p>
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</dd>
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<dt><strong>Data received</strong></dt>
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<dd>OUTPUT; BINARY(4)
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<p>The amount of data received from the virtual terminal in bytes. If no data
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is received from the virtual terminal, 0 is returned. Some read operations do
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not return any data.</p>
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<p>For graphic work stations, a maximum of 24 576 (24KB) bytes of data can
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be returned.</p>
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</dd>
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<dt><strong>Error code</strong></dt>
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<dd>I/O; CHAR(*)
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<p>The structure in which to return error information. For the format of the
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structure, see <a href="../apiref/error.htm#hdrerrcod">Error Code Parameter</a>.</p>
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</dd>
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</dl>
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<br>
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<h3><a name="HDROPCD">Read Operation Codes</a></h3>
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<p>The following table describes the operation codes that can be returned on a
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read request.<br>
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</p>
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<table border width="80%">
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<tr>
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<th align="left" colspan="3"><em>Read Operation Codes</em></th>
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</tr>
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<tr>
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<th align="center" valign="bottom">Value</th>
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<th align="left" valign="bottom">Response Name</th>
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<th align="left" valign="bottom">Description</th>
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</tr>
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<tr>
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<td align="center" valign="top" width="10%">1</td>
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<td align="left" valign="top" width="20%">Invite</td>
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<td align="left" valign="top" width="70%">The operating system and the
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application are ready to receive data. The server program is expected to follow
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this with a write operation when data becomes available from the client
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program.</td>
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</tr>
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<tr>
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<td align="center" valign="top">2</td>
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<td align="left" valign="top">Output only</td>
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<td align="left" valign="top">This read request returned some data. The server
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program should send the data to the client program. However, the operating
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system is not ready to receive data from the server program. The server program
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should not request any data from the client program yet. This response usually
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occurs because an application is performing several put operations to the
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virtual terminal device. After the last put operation by the application, a
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put/get operation code is usually returned on the read operation.</td>
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</tr>
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<tr>
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<td align="center" valign="top">3</td>
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<td align="left" valign="top">Put/get</td>
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<td align="left" valign="top">Data is returned from this read request and
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should be sent by the server program to the client program. The operating
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system is ready to receive data from the server program. The server program
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should wait for data from the client program.</td>
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</tr>
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<tr>
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<td align="center" valign="top">4</td>
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<td align="left" valign="top">Save display</td>
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<td align="left" valign="top">The operating system expects the server program
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to obtain the data from the current display and write the data to the virtual
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terminal. The operating system saves the display for later use, such as
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returning the display to the server program. The server program must indicate a
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save-display response on the write operation and send the saved display as data
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(that is, the saved display must be in the data buffer).</td>
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</tr>
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<tr>
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<td align="center" valign="top">5</td>
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<td align="left" valign="top">Restore display</td>
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<td align="left" valign="top">The data returned is a previously saved display.
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The server program should send the data to the client program.</td>
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</tr>
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<tr>
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<td align="center" valign="top">6</td>
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<td align="left" valign="top">Read immediate</td>
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<td align="left" valign="top">No data is returned from this read request. The
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operating system expects the server program to write data to the virtual
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terminal. Only data from input fields should be written.</td>
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</tr>
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<tr>
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<td align="center" valign="top">8</td>
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<td align="left" valign="top">Read display</td>
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<td align="left" valign="top">No data is returned from this read request. The
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operating system expects the server program to write data to the virtual
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terminal. The current display should be written.</td>
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</tr>
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<tr>
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<td align="center" valign="top">A</td>
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<td align="left" valign="top">Cancel invite</td>
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<td align="left" valign="top">No data is returned from this read request. The
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operating system expects the server program to signal the client program to
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cancel the outstanding invite operation. When it is canceled, the server
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program must perform a write operation to the virtual terminal and indicate a
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cancel invite response. Because the response has no data associated with it,
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the number of bytes to write must be set to 0 for the write operation.</td>
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</tr>
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<tr>
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<td align="center" valign="top">B</td>
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<td align="left" valign="top">Turn on message light</td>
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<td align="left" valign="top">No data is returned from this read request. A
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message has been received, and the user should be notified. The server program
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should signal the client program to turn on a display message indicator light
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or some other indicator.</td>
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</tr>
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<tr>
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<td align="center" valign="top">C</td>
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<td align="left" valign="top">Turn off message light</td>
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<td align="left" valign="top">No data is returned from this read request. The
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display message light or some other indicator should be set off.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Messages</h3>
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<table width="100%" cellpadding="5">
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<tr>
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<th align="left" valign="top">Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td align="left" valign="top" width="15%">CPF3C90 E</td>
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<td align="left" valign="top" width="85%">Literal value cannot be changed.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF87F2 E</td>
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<td align="left" valign="top">Virtual terminal handle &1 not valid.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF87F3 E</td>
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<td align="left" valign="top">Data buffer length &1 not valid.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF87F7 E</td>
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<td align="left" valign="top">Parameter value &1 not valid.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF87F8 E</td>
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<td align="left" valign="top">Unexpected internal system error occurred in
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program &1.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF9872 E</td>
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<td align="left" valign="top">Program or service program &1 in library
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&2 ended. Reason code &3.</td>
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</tr>
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</table>
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<br>
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<hr>
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API introduced: V2R1
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center">
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<a href="#Top_Of_Page">Top</a> |
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<a href="vt1a.htm">Virtual Terminal APIs</a> |
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<a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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