Using Persistent Sessions

Using Persistent Sessions
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Enabling Persistence
Delaying Session Load
Enabling Persistence for the Jetty Maven Plugin

It is sometimes useful to preserve existing Sessions across restarts of Jetty. The HashSessionManager supports this feature. If you enable persistence, the HashSessionManager saves all existing, valid Sessions to disk before shutdown completes. On restart, Jetty restores the saved Sessions.

Enabling Persistence

A SessionManager does just what its name suggests–it manages the lifecycle and state of sessions on behalf of a webapp. Each webapp must have its own unique SessionManager instance. Enabling persistence is as simple as configuring the HashSessionManager as the SessionManager for a webapp and telling it where on disk to store the sessions:


<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  .
  .
  .
  <Set name="sessionHandler">
    <New class="org.eclipse.jetty.servlet.SessionHandler">
      <Arg>
        <New class="org.eclipse.jetty.servlet.HashSessionManager">
          <Set name="storeDirectory">your/chosen/directory/goes/here</Set>
        </New>
      </Arg>
    </New>
  </Set>
  .
  .
  .
</Configure>

Tip

If you want to persist the sessions from multiple webapps:

Configure a separate HashSessionManager for each.
Assign to each a different value for 'storeDirectory'.

The above example uses a configuration file suitable for the ContextProvider, thus you might want to check out ???.

Delaying Session Load

You might need to ensure that the sessions are loaded AFTER the servlet environment starts up (by default, Jetty eagerly loads sessions as part of the container startup, but before it initializes the servlet environment). For example, the Wicket web framework requires the servlet environment to be available when sessions are activated.

Using SessionManager.setLazyLoad(true), Jetty loads sessions lazily either when it receives the first request for a session, or the session scavenger runs for the first time, whichever happens first. Here's how the configuration looks in XML:

<Set name="sessionHandler">
  <New class="org.eclipse.jetty.servlet.SessionHandler">
    <Arg>
      <New class="org.eclipse.jetty.servlet.HashSessionManager">
        <Set name="lazyLoad">true</Set>
      </New>
    </Arg>
  </New>
</Set>

Enabling Persistence for the Jetty Maven Plugin

To enable session persistence for the Jetty Maven plugin, set up the HashSessionManager in the configuration section like so:

<plugin>
  <groupId>org.eclipse.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <version>9.0.0.RC2 (or current version)</version>
  <configuration>
    <!-- ... -->
    <webAppConfig implementation="org.eclipse.jetty.maven.plugin.JettyWebAppContext">
      <defaultsDescriptor>/Users/jesse/docsync/jetty-documentation/target/classes/META-INF/webdefault.xml</defaultsDescriptor>
      <contextPath>${jetty.contextRoot}</contextPath>
      <sessionHandler implementation="org.eclipse.jetty.server.session.SessionHandler">
        <sessionManager implementation="org.eclipse.jetty.server.session.HashSessionManager">
          <storeDirectory>/Users/jesse/docsync/jetty-documentation/target/jetty-sessions</storeDirectory>
          <idleSavePeriod>1</idleSavePeriod>
        </sessionManager>
      </sessionHandler>
    </webAppConfig>
    <!-- ... -->
  </configuration>
</plugin>