Redisson implements Redis or Valkey based Tomcat Session Manager. It stores session of [Apache Tomcat](http://tomcat.apache.org) in Redis or Valkey and allows to distribute requests across a cluster of Tomcat servers. Implements non-sticky session management backed by Redis.
`keyPrefix` - string prefix applied to all keys. Allows to connect different Tomcat environments to the same Redis or Valkey instance.
`readMode` - read Session attributes mode. Two modes are available:
*`MEMORY` - stores attributes into local Tomcat Session and Redis. Further Session updates propagated to local Tomcat Session using Redis-based events.
*`REDIS` - stores attributes into Redis or Valkey only. Default mode.
`broadcastSessionEvents` - if `true` then `sessionCreated` and `sessionDestroyed` events are broadcasted across all Tomcat instances and cause all registered HttpSessionListeners to be triggered. Default is `false`.
`broadcastSessionUpdates` - if `true` and `readMode=MEMORY` then session updates are broadcasted across all Tomcat instances. Default is `true`.
`updateMode` - Session attributes update mode. Two modes are available:
*`DEFAULT` - session attributes are stored into Redis or Valkey only through the `Session.setAttribute` method. Default mode.
*`AFTER_REQUEST`
* In `readMode=REDIS` all changes of session attributes made through the `Session.setAttribute` method are accumulated in memory and stored into Redis or Valkey only after the end of the request.
* In `readMode=MEMORY` all session attributes are always stored into Redis or Valkey after the end of the request regardless of the `Session.setAttribute` method invocation. It is useful in case when some objects stored in session change their own state without `Session.setAttribute` method execution. Updated attributes are removed from all other Session instances if `broadcastSessionUpdates=true` and reloaded from Redis or Valkey when these attributes are requested.
`configPath` - path to Redisson YAML config. See [configuration](configuration.md) page for more details. In case session manager is configured programatically, a config object can be passed using the `setConfig()` method
Shared Redisson instance
Amount of Redisson instances created by Tomcat for multiple contexts could be reduced through JNDI registry:
1. Add shared redisson instance produced by `JndiRedissonFactory` into `tomcat/conf/server.xml` in `GlobalNamingResources` tag area:
```xml
<GlobalNamingResources>
<Resourcename="bean/redisson"
auth="Container"
factory="org.redisson.JndiRedissonFactory"
configPath="${catalina.base}/conf/redisson.yaml"
closeMethod="shutdown"/>
</GlobalNamingResources>
```
2. Add `JndiRedissonSessionManager` with resource link to redisson instance into `tomcat/conf/context.xml`
