MQTT

Overview

Beaver IoT integrates an MQTT Broker, allowing to subscribe to and publish messages via the MQTT protocol.

Subscribing to Messages

@Component  
public class MqttSubscription {  
      
    @Autowired  
    private MqttPubSubServiceProvider mqttPubSubServiceProvider;  
      
    @PostConstruct  
    public void init() {  
        String topicSubPath = "uplink/#";  
        boolean shared = true;  
        mqttPubSubServiceProvider.subscribe(topicSubPath, this::onMessage, shared);  
    }  
      
    public void onMessage(MqttMessage message) {  
        log.info("Received message: {}", message);  
    }  
}  

In this example, messages under the topic beaver-iot/+/uplink/# are subscribed to. Here, setting shared to true means a message will only be processed by a single node in the cluster.

Publishing Messages

@Component  
public class MqttPublish {  
      
    @Autowired  
    private MqttPubSubServiceProvider mqttPubSubServiceProvider;  
      
    public void testPublish() {  
        String topicSubPath = "downlink/test";  
        byte[] message = "test message".getBytes(StandardCharsets.UTF_8);  
        MqttQos qos = MqttQos.AT_MOST_ONCE;  
        boolean retained = false;  
        mqttPubSubServiceProvider.publish(topicSubPath, message, qos, retained);  
    }  
}  

In this example, the message is published to the topic beaver-iot/mqtt@${tenantId}/downlink/test, where ${tenantId} represents the tenant ID from the current context.