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   <title>Chapter&nbsp;10.&nbsp;Session Management</title><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><meta name="keywords" content="jetty, servlet, servlet-api, cometd, http, websocket, eclipse, maven, java, server, software"><link rel="home" href="index.html" title="Jetty"><link rel="up" href="jetty-admin-guide.html" title="Part&nbsp;III.&nbsp;Jetty Administration Guide"><link rel="prev" href="startup-jpms.html" title="Startup using the Java Platform Module System (JPMS)"><link rel="next" href="sessions-details.html" title="Session Components"><link xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" rel="shortcut icon" href="images/favicon.ico"><link rel="stylesheet" href="css/highlighter/foundation.css"><script src="js/highlight.pack.js"></script><script>
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            Version: 9.4.27-SNAPSHOT</span></td><td style="width: 50%"></td></tr></table><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter&nbsp;10.&nbsp;Session Management</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="startup-jpms.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a>&nbsp;</td><th width="60%" align="center">Part&nbsp;III.&nbsp;Jetty Administration Guide<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right">&nbsp;<a accesskey="n" href="sessions-details.html">Next <i class="fa fa-chevron-right" aria-hidden="true"></i></a></td></tr></table><hr></div><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="jetty-callout"><h5 class="callout"><a href="http://www.webtide.com/">Contact the core Jetty developers at
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      </p></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="session-management"></a>Chapter&nbsp;10.&nbsp;Session Management</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="session-management.html#jetty-sessions-architecture">Session Architecture</a></span></dt><dt><span class="section"><a href="sessions-details.html">Session Components</a></span></dt><dt><span class="section"><a href="session-configuration-housekeeper.html">The SessionIdManager and the Housekeeper</a></span></dt><dt><span class="section"><a href="session-configuration-sessioncache.html">The L1 Session Cache</a></span></dt><dt><span class="section"><a href="configuring-sessions-memory.html">Non-Persistent Sessions</a></span></dt><dt><span class="section"><a href="configuring-sessions-file-system.html">Persistent Sessions: File System</a></span></dt><dt><span class="section"><a href="configuring-sessions-jdbc.html">Persistent Sessions: JDBC</a></span></dt><dt><span class="section"><a href="configuring-sessions-mongo.html">Persistent Sessions: MongoDB</a></span></dt><dt><span class="section"><a href="configuring-sessions-infinispan.html">Persistent Sessions: Inifinspan</a></span></dt><dt><span class="section"><a href="configuring-sessions-hazelcast.html">Persistent Sessions: Hazelcast</a></span></dt><dt><span class="section"><a href="configuring-sessions-gcloud.html">Persistent Sessions: Google Cloud DataStore</a></span></dt><dt><span class="section"><a href="session-configuration-memcachedsessiondatastore.html">Persistent Sessions: The L2 Session Data Cache</a></span></dt><dt><span class="section"><a href="sessions-usecases.html">Session Use Cases</a></span></dt></dl></div><p>Sessions are a concept within the Servlet api which allow requests to store and retrieve information across the time a user spends in an application.
Choosing the correct session manager implementation is an important consideration for every application as each can fit and perform optimally in different situations.
If you need a simple in-memory session manager that can persist to disk then session management using the local file system can be a good place to start.
If you need a session manager that can work in a clustered scenario with multiple instances of Jetty, then the JDBC session manager can be an excellent option.
Jetty also offers more niche session managers that leverage backends such as MongoDB, Inifinispan, or even Google&#8217;s Cloud Data Store.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="jetty-sessions-architecture"></a>Session Architecture</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="session-management.html#_changes_in_session_architecture">Changes in Session Architecture</a></span></dt><dt><span class="section"><a href="session-management.html#_session_architecture_hierarchy">Session Architecture Hierarchy</a></span></dt><dt><span class="section"><a href="session-management.html#_configuring_sessions_in_the_jetty_distribution">Configuring Sessions in the Jetty Distribution</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_changes_in_session_architecture"></a>Changes in Session Architecture</h3></div></div></div><p>The architecture of Session Management Jetty changed significantly in Jetty 9.4.
These changes have resulted in Sessions not only being easier to configure but making them much more pluggable for various technologies.</p><p>In previous versions of Jetty, users were required to configure a separate <code class="literal">SessionIdManager</code> for each kind of session clustering technology being implemented (JDBC, MongoDB..etc.).
In Jetty 9.4, there is now a single <code class="literal">SessionIdManager</code> implementation which works across all types of session clustering technologies.
Likewise, prior to Jetty 9.4 there were several different instances of the <code class="literal">SessionManager</code> class.
Instead of a single <code class="literal">SessionManager</code> though, it has been done away with entirely, with most of it&#8217;s functionality moved to the <code class="literal">SesssionHandler</code> class.
Additionally, Jetty 9.4 introduced the concepts of a <code class="literal">SessionCache</code> and an associated <code class="literal">SessionDataStore</code> (both explained below).</p><p>Finally, Session scavenging has been re-worked.
Where previously each <code class="literal">SessionManager</code> instance would periodically scan the in-memory (or clustered) sessions for expired sessions, there is now a single generic scavenger thread which instructs the <code class="literal">SessionHandler</code> to clean up expired sessions.
Session expiration has been changed to use a much more efficient timer-based mechanism that avoids constant iteration over all current sessions in memory by the scavenger.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_session_architecture_hierarchy"></a>Session Architecture Hierarchy</h3></div></div></div><p>Each Jetty instance has a singular <code class="literal">SessionIdManager</code> to handle all session requests, regardless of clustering technology.
For each context on the server there is one (1) <code class="literal">SessionCache</code> which contains all of the Session objects for the given context.
The benefit of the <code class="literal">SessionCache</code> is to ensure that simultaneous requests accessing the same Session Id in the same context always operate on the same Session object.
The SessionCache implementation supplied with the Jetty distribution does just that: keeps Session objects in memory so that they can be shared between simultaneous requests.
However, it is possible to provide your own implementation that never shares Session objects should you require it.</p><p>Where the <code class="literal">SessionCache</code> handles Session information, Session data is stored in a <code class="literal">SessionDataStore</code> that is specific to the clustering technology being implemented.
There is only one (1) <code class="literal">SessionDataStore</code> per <code class="literal">SessionCache</code>.</p><p>Visually the session architecture can be represented like this:</p><div class="informalfigure"><div class="mediaobject"><img src="images/SessionsHierarchy.png" alt="SessionsHierarchy"></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_configuring_sessions_in_the_jetty_distribution"></a>Configuring Sessions in the Jetty Distribution</h3></div></div></div><p>Configuring session management involves selecting a <a class="link" href="startup-modules.html" title="Managing Startup Modules">module</a> for the desired type of <a class="link" href="session-configuration-sessioncache.html" title="The L1 Session Cache">session caching</a> behavior, and a module for the type of session persistence.</p><p>Jetty provides two different session caches: the <code class="literal">DefaultSessionCache</code> which holds sessions in memory, and the <code class="literal">NullSessionCache</code> which does not.
There is more information on both of these types of session caching and the circumstances which would lead you to select one or the other in the <a class="link" href="sessions-details.html" title="Session Components">Session Components</a> section, and more information on the configuration options of each in <a class="link" href="session-configuration-sessioncache.html" title="The L1 Session Cache">the L1 Session Cache</a> section.</p><p>For session persistence, Jetty provides a number of different implementations from which to choose including <a class="link" href="configuring-sessions-memory.html" title="Non-Persistent Sessions">non-persistence</a>, <a class="link" href="configuring-sessions-file-system.html" title="Persistent Sessions: File System">local file storage</a>, clustered technologies such as <a class="link" href="configuring-sessions-jdbc.html" title="Persistent Sessions: JDBC">JDBC</a>, <a class="link" href="configuring-sessions-mongo.html" title="Persistent Sessions: MongoDB">MongoDB</a>, <a class="link" href="configuring-sessions-infinispan.html" title="Persistent Sessions: Inifinspan">Inifinispan</a>, <a class="link" href="configuring-sessions-gcloud.html" title="Persistent Sessions: Google Cloud DataStore">Google Cloud Datastore</a>, and <a class="link" href="configuring-sessions-hazelcast.html" title="Persistent Sessions: Hazelcast">Hazelcast</a>.</p><p>Depending on your persistence technology, to enhance performance, you may want to use an L2 cache for session data, in which case Jetty provides the <a class="link" href="session-configuration-memcachedsessiondatastore.html" title="Persistent Sessions: The L2 Session Data Cache">memcached L2 session data cache</a>.</p></div></div></div><script type="text/javascript">
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