This library isn't just a wrapper around MQTT.js for angular >= 2. It uses observables and takes care of subscription handling and message routing.
ngx-mqtt is well suited for applications with many components and many subscribers.
The problem is, if you regulary subscribe to mqtt with client libraries like
MQTT.js, still every message is handled with an on-message-eventhandler, so you have to dispatch the received messages for yourself.
So, if you have multiple components using mqtt in your code, you just want to only receive the messages for your local filter.
Furthermore, if you destroy a component, you want to unsubscribe from mqtt, but only if no other component uses the same filter.
This library exposes a method
observe(filter), which returns an Observable. If you subscribe to this observable, the actual mqtt subscription is executed. The topic filter is used to only add matching mqtt messages to the observable. Every other execution of
observe(filter) with an already used filter will return the same observable. The observable keeps track of the subscribers and executes an mqtt unsubscribe method, if all subscribers have unsubscribed from the observable.
Simply install it from npm:
npm install ngx-mqtt --save
Since most of the opened issues here are caused by misconfiguration, please make sure your broker listens on websocket and you've configured the right port for it.
mosquitto seems to be the most common broker, so here is an example configuration with websockets.
pid_file /var/run/mosquitto.pid persistence true persistence_location /var/lib/mosquitto/ log_dest file /var/log/mosquitto/mosquitto.log listener 1883 listener 9001 127.0.0.1 protocol websockets include_dir /etc/mosquitto/conf.d
With this config the broker listens on
1883 for tcp connections and
9001 for websocket connections.
npm run serve:demo # go into demo folder, install npm dependencies and run ng serve
Keep in mind, that the demo is a self contained @angular/cli application, which depends on a ngx-mqtt release and not the source code.
For further usage use this module, see
npm run docs # build the documentationnpm run serve:docs # open a local webserver serving the documentation