Node Js Mqtt Client Doesn't Received Subscribed Messages When Broker Goes Down And Comes Up

I have created a mqtt node js client. My connection options are as follows. mqttOptions = { clientId: '100', keepAlive: 1000, clean: false, reconnectPeriod: '1000', will: willMessa

Solution 1:

We faced this issue with EMQ as the broker and with mqtt library for NodeJS. When it was mosquitto as broker, the client reconnects and gets all the messages it had subscribed. But, if it subscribes again, it gets n number of copies of the same message. As per the library document, it is recommended to check for connack and connack.sessionPresent for previous subscriptions.

We subscribed to all events of client and found that offline is the one that is called when the broker goes down. Then the reconnect and close gets called until the broker is up. Hence, here is how we did it. On offline, end the client forcefully and on completion of end, create a new client - the same function that was used to create client:

doConnect() {
    this.client = mqtt.connect('mqtt://myhost', this.myOptionsIfAny);
    this.client.on('connect', () => {
        this.client.subscribe('mytopics');
        this.client.on('message', (topic, message) => {
            // do processing
        });
        this.client.on('offline', () => {
            this.client.end(true, () => {
                doConnect();
            });
    });
}

Solution 2:

clean:'false',

Should 'false' definitely be a string? I presume it should be a boolean.