# Apache Tomcat 7

Version 7.0.40, May 5 2013

Links

- Docs Home
- Config Ref. Home
- FAQ
- User Comments

Top Level Elements

- Server
- Service

Executors

- Executor

Connectors

- HTTP
- AJP

Containers

- Context
- Engine
- Host
- Cluster

Nested Components

- Global Resources
- JarScanner
- Listeners
- Loader
- Manager
- Realm
- Resources
- Valve

Cluster Elements

- Cluster
- Manager
- Channel
- Channel/Membership
- Channel/Sender
- Channel/Receiver
- Channel/Interceptor
- Valve
- Deployer
- ClusterListener

Other

- Filter
- System properties

# The ClusterManager object

Table of Contents

> - Introduction
> - The <Manager>
> - Attributes
>   1. Common Attributes
>   2. org.apache.catalina.ha.session.DeltaManager Attributes
>   3. org.apache.catalina.ha.session.BackupManager Attributes

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 web application is deployed.

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.

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.
> > `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 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 `true`. Default value is `false`.

> > `sessionAttributeFilter`

> > 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 `^(userName|sessionHistory)$` will only replicate the two session attributes named `userName` and `sessionHistory`.

> org.apache.catalina.ha.session.DeltaManager Attributes

> > Attribute | Description
> > --- | ---
> > `expireSessionsOnShutdown` | 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 `true`. Default value is `false`.
> > `maxActiveSessions` | 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.
> > `notifySessionListenersOnReplication` | Set to `true` if you wish to have session listeners notified when sessions are created and expired across Tomcat nodes in the cluster.
> > `notifyContainerListenersOnReplication` | Set to `true` if you wish to have container listeners notified across Tomcat nodes in the cluster.
> > `stateTransferTimeout` | 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 `60` seconds.

> 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 `6`(synchronous). 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.
> > `maxActiveSessions` | 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.
> > `rpcTimeout` | Timeout for RPC message used for broadcast and transfer state from another map. Default value is `15000` milliseconds.

Comments

> Notice: This comments section collects your suggestions on improving documentation for Apache Tomcat.
> If you have trouble and need help, read Find Help page and ask your question on the tomcat-users mailing list. Do not ask such questions here. This is not a Q&A section.
> The Apache Comments System is explained here. Comments may be removed by our moderators if they are either implemented or considered invalid/off-topic.

Copyright © 1999-2013, Apache Software Foundation