Links Top Level Elements Connectors Containers Nested Components Cluster Elements | | Introduction |
A cluster manager is an extension to Tomcat's session manager interface,
org.apache.catalina.Manager
A cluster manager must implement the org.apache.catalina.ha.ClusterManager and is solely
responsible for how the session is replicated.
There are currently two different managers, the org.apache.catalina.ha.session.DeltaManager 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 org.apache.catalina.ha.session.BackupManager 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 webapp is deployed.
We are planning to add more managers with even more sophisticated backup mechanism to support even larger clusters.
Check back soon!
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| The <Manager> |
The <Manager> element defined inside the <Cluster> element
is the template defined for all web applications that are marked <distributable/>
in their web.xml file.
However, you can still override the manager implementation on a per web application basis,
by putting the <Manager> inside the <Context> element either in the
context.xml file or the server.xml file.
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| Attributes |
| Common Attributes |
| Attribute | Description |
|---|
className |
| name |
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 Cluster element to make it unique in the container.
| defaultMode |
Deprecated since 6.0.0
| notifyListenersOnReplication |
Set to true if you wish to have session listeners notified when
session attributes are being replicated or removed across Tomcat nodes in the cluster.
| expireSessionsOnShutdown |
When a webapplication 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 true.
Default value is false.
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| org.apache.catalina.ha.session.DeltaManager Attributes |
| Attribute | Description |
|---|
domainReplication |
Set to true if you wish sessions to be replicated only to members that have the same logical
domain set. If set to false, session replication will ignore the domain setting the
<Membership>
element.
| expireSessionsOnShutdown |
When a webapplication 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 true.
Default value is false.
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| org.apache.catalina.ha.session.BackupManager Attributes |
| Attribute | Description |
|---|
mapSendOptions |
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 8(asynchronous).
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