MQTT notes

MQTT

Relevant Conda packages

• Package Windows 10 64-bit emqttd v2.1.2 as Conda package (see here)
• Package Python paho-mqtt as Conda package (see here)

Notes

• retain flag can be used to deliver message to new clients subscribing after message is published

• persistent sessions can save values between broker restarts

• EMQTTD supports access control list security through plugins

  • For example, see the auth-mysql plugin:

     CREATE TABLE `mqtt_acl` (
       `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
       `allow` int(1) DEFAULT NULL COMMENT '0: deny, 1: allow',
       `ipaddr` varchar(60) DEFAULT NULL COMMENT 'IpAddress',
       `username` varchar(100) DEFAULT NULL COMMENT 'Username',
       `clientid` varchar(100) DEFAULT NULL COMMENT 'ClientId',
       `access` int(2) NOT NULL COMMENT '1: subscribe, 2: publish, 3: pubsub',
       `topic` varchar(100) NOT NULL DEFAULT '' COMMENT 'Topic Filter',
    

• Refresh paho.mqtt.client.Client with all retained messages:

   client.loop_stop()
   client.reconnect()
   client.loop_start()
  

• Consider URL route registrations for registering MQTT topic callback functions/methods

  • Python:
    • Consider Flask URL Route Registrations as idea for registering MQTT topic callback functions/methods
    • See also a description of how app.route works for static URLs and dynamic URL patterns.
  • Javascript: Consider Crossroads javascript routes system as idea for registering MQTT topic callback functions/methods

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