Server does not receive events after connection resumed

[cjacky475]

Hello, coming from a previous closed discussion. How to correctly resubscribe to my sensors/5 topic again in onConnectionResumed() method? When I receive no messages, after a while I get in the logs:

[ Thread-13] c.e.t.components.MQTTClient : Connection interrupted: 5134: The connection was closed unexpectedly.
[ Thread-13] c.e.t.components.MQTTClient : Connection resumed: clean session

But I no longer receive event when I send them, I have to restart the Spring Boot app for it to start working again. How to correctly solves this issue? Is there anything I could try? Thank you.

private final MqttClientConnectionEvents callbacks = new MqttClientConnectionEvents() {
        @Override
        public void onConnectionInterrupted(int errorCode) {
            logger.error("Connection interrupted: " + errorCode + ": " + CRT.awsErrorString(errorCode));
        }

        @Override
        public void onConnectionResumed(boolean sessionPresent) {
            logger.info("Connection resumed: " + (sessionPresent ? "existing session" : "clean session"));
        }
    };

public void connect(String clientID) {
        AwsIotMqttConnectionBuilder builder = AwsIotMqttConnectionBuilder
                .newMtlsBuilderFromPath("src/main/resources/certificate.pem.crt", "src/main/resources/private_key.pem.key");

        ClientBootstrap clientBootstrap = new ClientBootstrap(null, null);

        MqttClientConnection clientConnection = builder
                .withConnectionEventCallbacks(callbacks)
                .withCleanSession(false)
                .withBootstrap(clientBootstrap)
                .withClientId(clientID)
                .withCertificateAuthorityFromPath(null, "src/main/resources/AmazonRootCA1.pem")
                .withEndpoint("aaaaaaaaaaaa-ats.iot.us-east-2.amazonaws.com")
                .withProtocolOperationTimeoutMs(80000)
                .build();

        try {
            clientConnection.connect().get(TIMEOUT_SECONDS, TimeUnit.SECONDS);

            clientConnection.subscribe("sensors/5", QualityOfService.AT_LEAST_ONCE, mqttMessage -> {
                System.out.println("MESSAGE: " + Arrays.toString(mqttMessage.getPayload()));
            });
        } catch (InterruptedException | ExecutionException | TimeoutException e) {
            e.printStackTrace();
        }
    }

[jmklix]

According to the log you linked you are reconnection with a clean session

[ Thread-13] c.e.t.components.MQTTClient : Connection resumed: clean session

This means that the subscriptions from the previous session are lost and you won't receive any more events. This can be fixed by setting clean session to false. .withCleanSession(false). You can see this being setup for the examples here

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.