91 lines
6.4 KiB
HTML
91 lines
6.4 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Title" content="Program modification requirements for DDM" />
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<meta name="abstract" content="Remote files can be accessed by iSeries application programs written in the HLL and control language." />
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<meta name="description" content="Remote files can be accessed by iSeries application programs written in the HLL and control language." />
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<meta name="DC.subject" content="DDM architecture, extensions to, recompile considerations, recompiling programs, restrictions, high-level language (HLL), compiling programs, HLL (high-level language)" />
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<meta name="DC.Relation" scheme="URI" content="rbae5archres.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Program modification requirements for DDM</title>
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</head>
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<body id="rbae5compile"><a name="rbae5compile"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Program modification requirements for DDM</h1>
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<div><p>Remote files can be accessed by <span class="keyword">iSeries™</span> application
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programs written in the HLL and control language.</p>
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<div class="section"><p>In most cases, these applications can access both local or remote
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files without the programs being changed. However, some considerations and
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restrictions might require the programs to be changed and recompiled. These
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are grouped in three categories:</p>
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<ul><li><span class="keyword">iSeries</span> functions that
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are not supported by the DDM architecture, but for which a <span class="keyword">System/38™</span> extension
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to the architecture might exist. These functions can be used only when the
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source and target servers are <span class="keyword">System/38</span>s
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or <span class="keyword">iSeries server</span>s.</li>
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<li>Restrictions and considerations that apply when the <em>source</em> or <em>target</em> server
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is an <span class="keyword">iSeries server</span>.</li>
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<li>Restrictions and considerations that apply to all target servers (<span class="keyword">iSeries</span> servers and non-<span class="keyword">iSeries server</span>s).
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User programs accessing local files should program for abnormal conditions
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such as <em>No record found</em>, <em>End of file</em>, and <em>Record lock time-out
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on read for update</em>. These conditions can also occur when a remote file
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is being accessed using DDM. In addition, the use of DDM exposes the program
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to communication line failures while sending disk I/O operations. <p>When
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a communications failure occurs, the server sends an appropriate message to
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the job, which is returned to the application program as a generic file error.
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Each high-level language provides unique user syntax capabilities for user-controlled
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handling or default processing of exceptional results of a disk operation.
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Some languages might permit the user to retrieve the job message
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identification (ID) that would specifically indicate a DDM communications
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failure. Refer to the appropriate language manual for specific capabilities.</p>
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<p>For
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secondary SDLC lines, it is recommended that the INACTTMR parameter of the <span class="cmdname">Create
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Line Description (SDLC) (CRTLINSDLC)</span> command be set on the source
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and target servers to detect the stopping of polling by the primary server.
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This prevents the possibility of a DDM read-for-update record lock lasting
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indefinitely due to a communications failure on the primary server.</p>
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</li>
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</ul>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rbae5archres.htm">DDM architecture-related restrictions</a></strong><br />
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The items listed in this topic are DDM architecture-related restrictions. Therefore, application programs that use these items might have to be changed and recompiled before they can access remote files.</li>
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<li class="ulchildlink"><strong><a href="rbae5targetres.htm">iSeries source and target restrictions and considerations for DDM</a></strong><br />
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When the <em>source</em> server is an <span class="keyword">iSeries server</span>, <span class="keyword">iSeries</span> database functions can be used
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on remote files. There are some restrictions, however.</li>
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<li class="ulchildlink"><strong><a href="rbae5nonres.htm">Non-iSeries target restrictions and considerations for DDM</a></strong><br />
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In addition to the restrictions that apply when the target server
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is an <span class="keyword">iSeries server</span>, the restrictions
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in this topic also might apply when the target server is not an <span class="keyword">iSeries server</span> or
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a <span class="keyword">System/38</span>.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbae5prepddm.htm" title="There are several requirements that must be met for DDM to be used properly.">Prepare to use DDM</a></div>
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</div>
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</div>
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</body>
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</html>
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