mqttsngw-mqttbroker

MQTT-SN Gateway: MQTTBroker

This module is part of mqttsngw. It is responsible for handling and maintaining connections to the MQTT broker.

Factory

const Broker = require('mqttsngw-mqttbroker');
mqttsngw.attach(Broker(opts));

Creates a new MQTTBroker factory and attaches it to an existing instance of mqttsngw. opts has the following fields:

• log: Optional. An object containing logging callbacks for all log levels (error, warn, info, debug). Every callback is called with a human-readable message as the first argument followed by an object containing more information regarding the event: { error: (msg, info) => { ... }, ...}.
• broker: Mandatory. Callback function for creation of individual client configuration based on the clientId: (clientId) => clientOpts. clientOpts is an object:
  • url: Mandatory. URL pointing to the broker.
  • All other options accepted by the connect method of MQTT.js

State Machines

[MQTTBroker] Main

• listening: Listens for incoming connection requests from the event bus. If a request is received, a new instance of [MQTTBroker] Client is created and started.

[MQTTBroker] Client

Handles connection to the broker.

• init: Preparing the state machine.
• connect: Tries to connect to the broker.
• connected: The connection has been successfully established.

Events

Several events are consumed and emitted by the MQTTBroker module on the event bus.

Consumed

Event	State Machine	Description
brokerConnect,*,req	[MQTTBroker] Main	Connection request
brokerSubscribe,*,req	[MQTTBroker] Client	Request subscription to a topic
brokerUnsubscribe,*,req	[MQTTBroker] Client	Request unsubscribing a topic
brokerPublishFromClient,*,req	[MQTTBroker] Client	A sensors publishes a message to the broker
brokerPublishToClient,*,res	[MQTTBroker] Client	Response whether a message has been published to a client
brokerDisconnect,*,call	[MQTTBroker] Client	Disconnect from the broker

Emitted

Event	State Machine	Description
brokerConnect,*,res	[MQTTBroker] Client	Response to a connection request
brokerSubscribe,*,res	[MQTTBroker] Client	Response to a subscription request
brokerUnsubscribe,*,res	[MQTTBroker] Client	Response to a unsubscribe request
brokerPublishFromClient,*,res	[MQTTBroker] Client	Response whether a message has been published to the broker
brokerPublishToClient,*,req	[MQTTBroker] Client	The broker publishes a message to the client
brokerDisconnect,*,notify	[MQTTBroker] Client	Informs the client that the connection has been closed