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<!DOCTYPE document [
<!ENTITY project SYSTEM "project.xml">
]>
<document url="cluster-manager.html">
&project;
<properties>
<author email="fhanik@apache.org">Filip Hanik</author>
<title>The ClusterManager object</title>
</properties>
<body>
<section name="Table of Contents">
<toc/>
</section>
<section name="Introduction">
<p>A cluster manager is an extension to Tomcat's session manager interface,
<code>org.apache.catalina.Manager</code>.
A cluster manager must implement the
<code>org.apache.catalina.ha.ClusterManager</code> and is solely responsible
for how the session is replicated.<br/>
There are currently two different managers, the
<code>org.apache.catalina.ha.session.DeltaManager</code> replicates deltas of
session data to all members in the cluster. This implementation is proven and
works very well, but has a limitation as it requires the cluster members to be
homogeneous, all nodes must deploy the same applications and be exact
replicas. The <code>org.apache.catalina.ha.session.BackupManager</code> also
replicates deltas but only to one backup node. The location of the backup node
is known to all nodes in the cluster. It also supports heterogeneous
deployments, so the manager knows at what locations the web application is
deployed.</p>
</section>
<section name="The <Manager>">
<p>The <code><Manager></code> element defined inside the
<code><Cluster></code> element is the template defined for all web
applications that are marked <code><distributable/></code> in their
<code>web.xml</code> file. However, you can still override the manager
implementation on a per web application basis, by putting the
<code><Manager></code> inside the <code><Context></code> element
either in the <code><a href="context.html">context.xml</a></code> file or the
<code><a href="index.html">server.xml</a></code> file.</p>
</section>
<section name="Attributes">
<subsection name="Common Attributes">
<attributes>
<attribute name="className" required="true">
</attribute>
<attribute name="name" required="false">
<b>The name of this cluster manager, the name is used to identify a
session manager on a node. The name might get modified by the
<code>Cluster</code> element to make it unique in the container.</b>
</attribute>
<attribute name="defaultMode" required="false">
<b>Deprecated since 6.0.0</b>
</attribute>
<attribute name="notifyListenersOnReplication" required="false">
Set to <code>true</code> if you wish to have session listeners notified
when session attributes are being replicated or removed across Tomcat
nodes in the cluster.
</attribute>
<attribute name="expireSessionsOnShutdown" required="false">
When a web application is being shutdown, Tomcat issues an expire call
to each session to notify all the listeners. If you wish for all
sessions to expire on all nodes when a shutdown occurs on one node, set
this value to <code>true</code>. Default value is <code>false</code>.
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.ha.session.DeltaManager Attributes">
<attributes>
<attribute name="domainReplication" required="false">
<b>Deprecated since 6.0.0</b><br/>
If you wish sessions to be replicated only to members that have the
same logical domain set, use
<code><a href="cluster-interceptor.html">DomainFilterInterceptor </a></code>.
</attribute>
<attribute name="expireSessionsOnShutdown" required="false">
When a web application is being shutdown, Tomcat issues an expire call
to each session to notify all the listeners. If you wish for all
sessions to expire on all nodes when a shutdown occurs on one node, set
this value to <code>true</code>.
Default value is <code>false</code>.
</attribute>
<attribute name="maxActiveSessions" required="false">
The maximum number of active sessions that will be created by this
Manager, or -1 (the default) for no limit. For this manager, all
sessions are counted as active sessions irrespective if whether or not
the current node is the primary node for the session.
</attribute>
<attribute name="notifySessionListenersOnReplication" required="false">
Set to <code>true</code> if you wish to have session listeners notified
when sessions are created and expired across Tomcat nodes in the
cluster.
</attribute>
<attribute name="notifyContainerListenersOnReplication" required="false">
Set to <code>true</code> if you wish to have container listeners notified
across Tomcat nodes in the cluster.
</attribute>
<attribute name="stateTransferTimeout" required="false">
The time in seconds to wait for a session state transfer to complete
from another node when a node is starting up.
Default value is <code>60</code> seconds.
</attribute>
<attribute name="sessionAttributeFilter" required="false">
A regular expression used to filter, which session attributes will
be replicated. An attribute will only be replicated, if its name
matches this pattern. If the pattern is not set (default), all
attributes are eligible for replication. As an example, the value
<code>^(userName|sessionHistory)$</code> will only replicate the two
session attributes named <code>userName</code> and
<code>sessionHistory</code>.
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.ha.session.BackupManager Attributes">
<attributes>
<attribute name="mapSendOptions" required="false">
The backup manager uses a replicated map, this map is sending and
receiving messages. You can setup the flag for how this map is sending
messages, the default value is <code>6</code>(synchronous).<br/>
Note that if you use asynchronous messaging it is possible for update
messages for a session to be processed by the receiving node in a
different order to the order in which they were sent.
</attribute>
<attribute name="maxActiveSessions" required="false">
The maximum number of active sessions that will be created by this
Manager, or -1 (the default) for no limit. For this manager, only
sessions where the current node is the primary node for the session are
considered active sessions.
</attribute>
<attribute name="rpcTimeout" required="false">
Timeout for RPC message used for broadcast and transfer state from
another map.
Default value is <code>15000</code> milliseconds.
</attribute>
</attributes>
</subsection>
</section>
</body>
</document>