Mqtt-Integration in Spring Boot

Question

i try to integrate mqtt in my Spring Boot Java Project.

My depdency:

<dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-mqtt</artifactId>
        <scope>compile</scope>
        <exclusions>
            <exclusion>
                <artifactId>jackson-module-kotlin</artifactId>
                <groupId>com.fasterxml.jackson.module</groupId>
            </exclusion>
        </exclusions>
    </dependency>

I created a Java-Class named MqttClient. Here i try this:

IMqttClient publisher = new org.eclipse.paho.client.mqttv3.MqttClient("pfad", publisherId);

I get a Error here: org.eclipse.paho.client.mqttv3.MqttClient

Error:Unhandled exception: org.eclipse.paho.client.mqttv3.MqttException

Any idea whats wrong?

Answer 1

Can't figure out what is the problem? I did solve the same problem in following fashion. See if it works for you. I have a mqtt gateway class defined as below.

import org.springframework.integration.annotation.MessagingGateway;

@MessagingGateway(defaultRequestChannel = "mqttPromiseOutboundChannel")
public interface MqttPromiseGateway {

    void sendToMqtt(String data);
}

When I want to send a message to Mqtt, I autowire the defined gateway class.

@Autowired
private MqttPromiseGateway mqttPromiseGateway;

Now I can send a message over that Mqtt channel using that gateway.

 mqttPromiseGateway.sendToMqtt(content);

We also define a service for MqttProducer.

@Service
public class DemoMqttProducer {

    @Bean
    public MqttPahoClientFactory mqttClientFactory() {
        DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
        MqttConnectOptions options = new MqttConnectOptions();
        options.setServerURIs(new String[] { "tcp://localhost:1883" });
        options.setUserName("myusername");
        options.setPassword("mypassword#".toCharArray());
        factory.setConnectionOptions(options);
        return factory;
    }


    @Bean
    @ServiceActivator(inputChannel = "mqttPromiseOutboundChannel")
    public MessageHandler mqttPromiseOutbound() {
        MqttPahoMessageHandler messageHandler =
                new MqttPahoMessageHandler("testClient", mqttClientFactory());
        messageHandler.setAsync(true);
        messageHandler.setDefaultTopic("Promise");
        return messageHandler;
    }

    @Bean
    public MessageChannel mqttOutboundChannel() {
        return new DirectChannel();
    }
    @Bean
    public MessageChannel mqttPromiseOutboundChannel() {
        return new DirectChannel();
    }
    @Bean
    public IntegrationFlow mqttInFlow() {
        return IntegrationFlows.from(mqttInbound())
                .transform(p -> p + ", received from MQTT")
                .handle(logger())
                .get();
    }

    @Bean
    public MessageProducerSupport mqttInbound() {
        MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter("siSampleConsumer",
                mqttClientFactory(), "Promise");
        adapter.setCompletionTimeout(5000);
        adapter.setConverter(new DefaultPahoMessageConverter());
        adapter.setQos(1);
        return adapter;
    }    

}

The method mqttInflow will get the incoming message and send it to logger. If you want to handle it differently, you need to change that method.