@mangar2/mqttclient NPM

Abstract

Provides a standard client to communicate with the mqtt broker


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