59 lines
2.9 KiB
HTML
59 lines
2.9 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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<LINK rel="stylesheet" type="text/css" href="../../../rzahg/ic.css">
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<title>Configure scheduled invalidation</title>
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</head>
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<BODY>
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<!-- Java sync-link -->
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<SCRIPT LANGUAGE="Javascript" SRC="../../../rzahg/synch.js" TYPE="text/javascript"></SCRIPT>
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<h6><A NAME="sescfgschedinval"></A>Configure scheduled invalidation</h6>
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<p>Instead of relying on the periodic invalidation timer that runs
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on an interval based on the session timeout parameter, you can set specific
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times for the session management facility to scan for invalidated sessions
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in a distributed environment. When used with distributed sessions, this feature
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has the following benefits:</p>
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<ul>
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<li>You can schedule the scan for invalidated sessions for times of low application
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server activity, avoiding contention between invalidation scans of database
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or another WebSphere Application Server - Express instance and read and write operations
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to service HTTP session requests.</li>
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<li>Significantly fewer external write operations can occur when running with
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the End of Service Method Write mode because the last access time of the session
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does not need to be written out on each HTTP request. (Manual Update options
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and Time Based Write options already minimize the writing of the last access
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time.)</li>
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</ul>
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<p><strong>Usage considerations</strong></p>
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<ul>
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<li>With scheduled invalidation configured, HttpSession timeouts are not strictly
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enforced. Instead, all invalidation processing is handled at the configured
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invalidation times.</li>
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<li>HttpSessionBindingListener processing is handled at the configured invalidation
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times unless the HttpSession.invalidate( ) method is explicitly called.</li>
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<li>The HttpSession.invalidate() method immediately invalidates the session
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from both the session cache and the external store.</li>
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<li>The periodic invalidation thread still runs with scheduled invalidation.
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If the current hour of the day does not match one of the configured hours,
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sessions that have exceeded the invalidation interval are removed from cache,
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but not from the external store. Another request for that session results
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in returning that session back into the cache.</li>
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<li>When the periodic invalidation thread runs during one of the configured
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hours, all sessions that have exceeded the invalidation interval are invalidated
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by removal from both the cache and the external store.</li>
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<li>The periodic invalidation thread can run more than once during an hour
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and does not necessarily run exactly at the top of the hour.</li>
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<li>If you specify the interval for the periodic invalidation thread using
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the HttpSessionReaperPollInterval custom property, do not specify a value
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of more than 3600 seconds (1 hour) to ensure that invalidation processing
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happens at least once during each hour.</li>
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</ul>
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</body>
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</html>
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