169 lines
6.1 KiB
HTML
169 lines
6.1 KiB
HTML
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<!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>Virtual Terminal Run-Time Example</title>
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<!-- Begin Header Records ========================================= -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- VT3A SCRIPT A converted by B2H R4.1 (346) (CMS) by HOLTJM at -->
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<!-- RCHVMW2 on 5 Feb 1999 at 07:55:19 -->
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<!-- File cleanup completed Sept 2001 -->
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<!-- End Header Records -->
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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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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>Virtual Terminal Run-Time Example</h2>
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<p>To help understand how virtual terminal APIs are used, the following example
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shows how the i5/OS<SUP>(TM)</SUP> operating system, server program, client program, and work
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station device (display and keyboard) interact when processing a system
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request.</p>
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<p>This example starts with the server program waiting for a response from the
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client program, which is waiting for data from the user (keyboard).</p>
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<ol>
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<li>System request processing starts when you press the appropriate System
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Request key on the work station keyboard.<br>
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<br>
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</li>
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<li>The client program informs the server program that the System Request key
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has been pressed. The protocol used in this case is unique to the particular
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implementation of these two programs.<br>
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<br>
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</li>
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<li>The server program calls the Write to Virtual Terminal (QTVWRTVT) API for a
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write request. The flag for the System Request key must be set for this write
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request. No data is sent to the virtual terminal at this time.<br>
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<br>
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</li>
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<li>The i5/OS licensed program creates a data queue entry for informing the
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server program that data is available to be read.<br>
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<br>
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</li>
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<li>The server program removes the entry from the data queue by calling the
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Receive Data Queue (QRCVDTAQ) API and then calls the Read from Virtual Terminal
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(QTVRDVT) API for a read request. The Cancel Invite operation code is returned.
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No data is received from the virtual terminal at this time.
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<p>To prevent the client program from sending anymore data (screens), the
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server program informs the client program that it is no longer receiving data
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from the client program.</p>
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<p>The server program calls the QTVWRTVT API for a write request. The Operation
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Code parameter is set to Cancel Invite. No data is sent to the virtual terminal
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at this time.</p>
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</li>
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<li>The i5/OS licensed program creates a data queue entry for informing the
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server program that data is available to be read.<br>
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<br>
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</li>
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<li>The server program removes the entry from the data queue by calling the
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QRCVDTAQ API and then calls the QTVRDVT API for a read request. A Save Screen
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operation code is returned. No data is received from the virtual terminal at
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this time.
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<p>The server program gets the current screen. This may require requesting the
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current screen from the client program.</p>
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<p>The server program calls the QTVWRTVT API for a write request, sending the
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current screen to the virtual terminal. The Operation Code parameter must be
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set to Save Screen.</p>
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</li>
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<li>The i5/OS licensed program creates a data queue entry for informing the
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server program that data is available to be read.<br>
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<br>
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</li>
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<li>The server program removes the entry from the data queue by calling the
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QRCVDTAQ API and then calls the QTVRDVT API for a read request. A Put/Get
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operation code is returned. The data read will be the actual System Request
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menu.
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<p>The server program sends this data to the client program and waits for a
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response.</p>
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</li>
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<li>The client program updates the display with the System Request menu and
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waits for a response from the user. The resulting response is sent to the
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server program.<br>
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<br>
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</li>
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<li>The response is received from the client program, and the server program
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calls the QTVWRTVT API for a write request, sending the response to the virtual
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terminal.
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<p><strong>Note:</strong> What happens at this point depends on the response to
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the System Request menu. Additional data may be received from and sent to the
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virtual terminal. After the response is processed, the following steps
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occur.</p>
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</li>
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<li>The i5/OS licensed program creates a data queue entry for informing the
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server program that data is available to be read.<br>
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<br>
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</li>
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<li>The server program removes the entry from the data queue by calling the
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QRCVDTAQ API and then performs a call to the QTVRDVT API for a read request. A
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Put operation code is returned. The data read is the saved (current) screen
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that was previously written by the server program to the virtual terminal.
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<p>The server program sends the saved screen to the client program but does not
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wait for a response.</p>
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</li>
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<li>The client program updates the work station display with the saved
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screen.<br>
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<br>
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</li>
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<li>The i5/OS licensed program creates a data queue entry for informing the
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server program that data is available to be read.<br>
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<br>
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</li>
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<li>The server program removes the entry from the data queue by calling the
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QRCVDTAQ API. An Invite operation code is returned. Note that no data is
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received from the virtual terminal at this time.<br>
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<br>
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</li>
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<li>The client program is once again waiting for user data, and the server
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program is waiting for data from the client program.</li>
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</ol>
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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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