@mangar2/mqttclient

Abstract

Provides a standard client to communicate with the mqtt broker

Contents

• Meta
• Type definitions
• Class MqttClient
  • Parameters
  • Members
  • Methods
    • _createMemoryUsageMessage
    • close
    • isShuttingDown
    • on
    • publish
    • reconnect
    • registerCloseFunction
    • registerRecipient
    • registerSender
    • run
    • updateSubscriptions

Meta

File	mqttclient.js
Abstract	Provides a standard client to communicate with the mqtt broker
Author	Volker Böhm
Copyright	Copyright ( c ) 2020 Volker Böhm
License	This software is licensed under the GNU LESSER GENERAL PUBLIC LICENSE Version 3 . It is furnished "as is" , without any support , and with no warranty , express or implied , as to its usefulness for any purpose .

Type definitions

LogPattern {Object}

Name	Type	Description
topic	string	log topic pattern
module	string	module to log , "send" , "receive" or "all" ( for all modules )
level	number	log level for the pattern

Callback definitions

PollCallback

Callback to retrieve messages to be sent to the mqtt broker

PollCallback returns

Type	Description
Array.<Message>, Message	messages to send to the broker

Class MqttClient

new MqttClient(options)

Creates a standard mqtt client , connects and subscribes to the broker

MqttClient Parameters

Name	Type	Description
options	Object	options to provide for connection

options properties

Name	Type	Attribute	Default	Description
clientId	string			unique id of the client
broker	Object			information of the broker to connect to
listener	number			port this client will listen to
version	string	optional	'1 . 0'	interface version
keepAliveInSeconds	string	optional		connection keep alive time in seconds
clean	boolean	optional	true	clean the broker session on disconnect
retry	number			amount of retries to send messages to the broker
log	Array.<LogPattern>			logging settings

broker properties

Name	Type	Description
host	string	hostname of the broker
port	number	port of the broker

MqttClient Members

Name	Type	description
connected	boolean	Connection status . true , iff connected
token	Object.<send:string, receive:string>	Send and receive token to be used to communicate with the mqtt broker
version	string	Gets/Sets the interface version to use

MqttClient Methods

_createMemoryUsageMessage

_createMemoryUsageMessage () => {Message}

Creates a message showing the memory usage

_createMemoryUsageMessage returns

Type	Description
Message	the memory usage message with the topic $SYS/ [ clientId ] /memory usage

close

async close ()

closes the client by shutting down all services and loops

isShuttingDown

isShuttingDown () => {boolean}

checks , if the client is shutting down . Every loop must stop once isShuttingDown is true

isShuttingDown returns

Type	Description
boolean	true , iff shutting down

on

on (event, callback)

Sets a callback .

on Parameters

Name	Type	Description
event	string	supports 'shutdown'
callback	function

on throws

Type	Description
Error	if the event is not supported
Error	if the callback is not 'function'

publish

publish (message, serviceName)

Publishes a message to the broker

publish Parameters

Name	Type	Description
message	Message	message to publish
serviceName	string	name of the publishing service

message properties

Name	Type	Description
qos	number	quality of service ( 0 , 1 , 2 )
retain	boolean	true to create a retain message

reconnect

async reconnect ()

Connects and subscribes to the broker

registerCloseFunction

registerCloseFunction (closeFunction)

Registers close functions . It will be called when the client close function is called

registerCloseFunction Parameters

Name	Type	Description
closeFunction	function	function to be called on close commands

registerRecipient

async registerRecipient (serviceName, subscriptions, callback)

Registeres a recipient

registerRecipient Parameters

Name	Type	Description
serviceName	string	name of the subscribing service
subscriptions	Object	subscription entries of format { topic : qos , topic : qos , . . . }
callback	function	function to send received messages to

registerRecipient throws

Type	Description
Error	If subscriptions are not well formatted or callback is not a function

registerSender

registerSender (intervalInMilliseconds, callback)

Registeres a service sending messages in intervals . The service must provide a function ( callback ) without parameters returing an array of messages . The messages will then be sent to the broker

registerSender Parameters

Name	Type	Description
intervalInMilliseconds	number	interval in milliseconds to call the senders callback
callback	PollCallback	function to call

run

async run ()

Starts the mqttclient . Opens the listener and connects to the broker

updateSubscriptions

async updateSubscriptions (serviceName, subscriptions)

Updates the subscriptions

updateSubscriptions Parameters

Name	Type	Description
serviceName	string	name of the subscribing service
subscriptions	Object	subscription entries of format { topic : qos , topic : qos , . . . }

updateSubscriptions throws

Type	Description
Error	If subscriptions are not well formatted