Due to the design of MQTT where you can only make a connection with a unique client id, is it possible to use the same connection to publish and subscribe in Spring Framework/Boot using Integration?
Taking this very simple example, it would connect to the MQTT broker to subscribe and get messages, but if you would want to publish a message, the first connection will disconnect and re-connect after the message is sent.
@Bean
public MqttPahoClientFactory mqttClientFactory() {
DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
factory.setServerURIs("tcp://localhost:1883");
factory.setUserName("guest");
factory.setPassword("guest");
return factory;
}
// publisher
@Bean
public IntegrationFlow mqttOutFlow() {
return IntegrationFlows.from(CharacterStreamReadingMessageSource.stdin(),
e -> e.poller(Pollers.fixedDelay(1000)))
.transform(p -> p + " sent to MQTT")
.handle(mqttOutbound())
.get();
}
@Bean
public MessageHandler mqttOutbound() {
MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler("siSamplePublisher", mqttClientFactory());
messageHandler.setAsync(true);
messageHandler.setDefaultTopic("siSampleTopic");
return messageHandler;
}
// consumer
@Bean
public IntegrationFlow mqttInFlow() {
return IntegrationFlows.from(mqttInbound())
.transform(p -> p + ", received from MQTT")
.handle(logger())
.get();
}
private LoggingHandler logger() {
LoggingHandler loggingHandler = new LoggingHandler("INFO");
loggingHandler.setLoggerName("siSample");
return loggingHandler;
}
@Bean
public MessageProducerSupport mqttInbound() {
MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter("siSampleConsumer",
mqttClientFactory(), "siSampleTopic");
adapter.setCompletionTimeout(5000);
adapter.setConverter(new DefaultPahoMessageConverter());
adapter.setQos(1);
return adapter;
}
Working with 2 separate connections becomes difficult if you need to wait for an answer/result after publishing a message...
