| # Apache Tomcat 6.0 |

# Apache Tomcat Configuration Reference ## The ClusterListener object |
Introduction
The `org.apache.catalina.ha.ClusterListener` base class lets you listen in on messages that are received by the `Cluster` component.
org.apache.catalina.ha.session.ClusterSessionListener
When using the DeltaManager, the messages are received by the Cluster object and are propagated to the to the manager through this listener.
org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener
Listens for session Id changes. This listener is only used if you are using mod_jk along with the `jvmRoute` attribute where the session Id can change. In the event of a change, the `JvmRouteBinderValve` will broadcast the session change and it will get picked up by this listener.
Attributes
> Common Attributes
> > Attribute | Description
> > --- | ---
> > `className` |
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