70 lines
4.3 KiB
HTML
70 lines
4.3 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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<html lang="en-us" xml:lang="en-us">
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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="DC.Type" content="reference" />
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<meta name="DC.Title" content="Interactive file processing with DDM" />
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<meta name="abstract" content="Consider these items when using interactive file processing with DDM." />
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<meta name="description" content="Consider these items when using interactive file processing with DDM." />
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<meta name="DC.Relation" scheme="URI" content="rbae5perfcon.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Identifier" content="rbae5interactivefp" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Interactive file processing with DDM</title>
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</head>
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<body id="rbae5interactivefp"><a name="rbae5interactivefp"><!-- --></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">Interactive file processing with DDM</h1>
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<div><p>Consider these items when using interactive file processing with
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DDM.</p>
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<div class="section"><ul><li>The greater the number of random file operations per unit of performance
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measurement, the greater the difference between local and remote file processing
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because each operation has to be sent separately across the communications
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line. DDM cannot anticipate the next operation. <p>Using a simple inquiry
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application that produces display output, by using workstation subfile support
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(as an example), consider an application that does two random record retrievals
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per Enter key versus one that does 15 random record retrievals. The operator
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might barely notice a delay in response time when two records
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are retrieved. However, there would be a noticeable difference between local
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and remote response time when 15 records are retrieved randomly from the remote
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server.</p>
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</li>
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<li>Use of display station pass-through should be considered when the amount
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of data transferred back to the local (source) server per unit of performance
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measurement significantly exceeds the amount of data presented on the display.
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Test results have shown that the total elapsed time between a single deblocked
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DDM get record operation and an equivalent user-written APPC operation is
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very close, with APPC being slightly quicker. The DDM operation does require
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more processing seconds than the direct APPC interface. <p>Also, because
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each DDM operation always requires an operation result response from the remote
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server to ensure data integrity, user-designed partner APPC programs can offer
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an advantage for update, add, and delete operations by not validating the
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result of the operation until a later time.</p>
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</li>
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<li>Be aware that additional time is needed when accessing files on other
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servers, particularly the time required for communications over the line.
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This should be considered when determining whether the file should be a local
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or remote file, especially if it is to be used often.</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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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbae5perfcon.htm" title="These topics provide information to help you improve performance when using DDM and also provide some information about when to use something other than DDM to accomplish some functions.">Performance considerations for 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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