Redis Clustering

Redis Clustering

Cross-node broadcasting via Redis pub/sub. Messages broadcast on one node are delivered to clients on all nodes.

Maven Coordinates

<dependency>
    <groupId>org.atmosphere</groupId>
    <artifactId>atmosphere-redis</artifactId>
    <version>LATEST</version> <!-- check Maven Central for latest -->
</dependency>

Quick Start

Configure the broadcaster class and Redis connection:

org.atmosphere.cpr.broadcasterClass=org.atmosphere.redis.RedisBroadcaster
org.atmosphere.redis.url=redis://localhost:6379

Or use RedisClusterBroadcastFilter with the default broadcaster:

org.atmosphere.cpr.broadcastFilterClasses=org.atmosphere.redis.RedisClusterBroadcastFilter
org.atmosphere.redis.url=redis://localhost:6379

Spring Boot

atmosphere:
  broadcaster-class: org.atmosphere.redis.RedisBroadcaster
  init-params:
    org.atmosphere.redis.url: redis://localhost:6379

Configuration

Property	Default	Description
org.atmosphere.redis.url	redis://localhost:6379	Redis connection URL
org.atmosphere.redis.password	(none)	Optional password

How It Works

RedisBroadcaster extends DefaultBroadcaster and publishes every broadcast message to a Redis channel. Each node subscribes to the same channel and delivers incoming messages to its local clients. A node ID header prevents echo (re-broadcasting messages that originated locally).

Key Classes

Class	Purpose
RedisBroadcaster	Broadcaster that publishes/subscribes via Redis pub/sub
RedisClusterBroadcastFilter	ClusterBroadcastFilter for use with DefaultBroadcaster

See Also

• Kafka Clustering
• Core Runtime — Broadcaster API