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For the latest stable version, please use Spring Framework 6.2.0! |
Order of Messages
Messages from the broker are published to the clientOutboundChannel, from where they are
written to WebSocket sessions. As the channel is backed by a ThreadPoolExecutor, messages
are processed in different threads, and the resulting sequence received by the client may
not match the exact order of publication.
If this is an issue, enable the setPreservePublishOrder flag, as the following example shows:
@Configuration
@EnableWebSocketMessageBroker
public class MyConfig implements WebSocketMessageBrokerConfigurer {
@Override
protected void configureMessageBroker(MessageBrokerRegistry registry) {
// ...
registry.setPreservePublishOrder(true);
}
}The following example shows the XML configuration equivalent of the preceding example:
<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 preserve-publish-order="true">
<!-- ... -->
</websocket:message-broker>
</beans>When the flag is set, messages within the same client session are published to the
clientOutboundChannel one at a time, so that the order of publication is guaranteed.
Note that this incurs a small performance overhead, so you should enable it only if it is required.