External Broker

The simple broker is great for getting started but supports only a subset of STOMP commands (it does not support acks, receipts, and some other features), relies on a simple message-sending loop, and is not suitable for clustering. As an alternative, you can upgrade your applications to use a full-featured message broker.

See the STOMP documentation for your message broker of choice (such as RabbitMQ, ActiveMQ, and others), install the broker, and run it with STOMP support enabled. Then you can enable the STOMP broker relay (instead of the simple broker) in the Spring configuration.

The following example configuration enables a full-featured broker:

Java
Kotlin
Xml

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfiguration implements WebSocketMessageBrokerConfigurer {

	@Override
	public void registerStompEndpoints(StompEndpointRegistry registry) {
		registry.addEndpoint("/portfolio").withSockJS();
	}

	@Override
	public void configureMessageBroker(MessageBrokerRegistry registry) {
		registry.enableStompBrokerRelay("/topic", "/queue");
		registry.setApplicationDestinationPrefixes("/app");
	}

}

@Configuration
@EnableWebSocketMessageBroker
class WebSocketConfiguration : WebSocketMessageBrokerConfigurer {

	override fun registerStompEndpoints(registry: StompEndpointRegistry) {
		registry.addEndpoint("/portfolio").withSockJS()
	}

	override fun configureMessageBroker(registry: MessageBrokerRegistry) {
		registry.enableStompBrokerRelay("/topic", "/queue")
		registry.setApplicationDestinationPrefixes("/app")
	}
}

<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xmlns:websocket="http://www.springframework.org/schema/websocket"
	   xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		https://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/websocket
		https://www.springframework.org/schema/websocket/spring-websocket.xsd">

	<websocket:message-broker application-destination-prefix="/app">
		<websocket:stomp-endpoint path="/portfolio">
			<websocket:sockjs />
		</websocket:stomp-endpoint>
		<websocket:stomp-broker-relay prefix="/topic,/queue" />
	</websocket:message-broker>
</beans>

The STOMP broker relay in the preceding configuration is a Spring MessageHandler that handles messages by forwarding them to an external message broker. To do so, it establishes TCP connections to the broker, forwards all messages to it, and then forwards all messages received from the broker to clients through their WebSocket sessions. Essentially, it acts as a “relay” that forwards messages in both directions.

Add io.projectreactor.netty:reactor-netty and io.netty:netty-all dependencies to your project for TCP connection management.

Furthermore, application components (such as HTTP request handling methods, business services, and others) can also send messages to the broker relay, as described in Sending Messages, to broadcast messages to subscribed WebSocket clients.

In effect, the broker relay enables robust and scalable message broadcasting.