@mangar2/connections

Abstract

Manages connections of the yaha Mqtt broker and provides functionality to receive/send messages from/to the managed connections in three service levels ( qos 0 , 1 , 2 )

Contents

• Meta
• Class Connections
  • Parameters
  • Methods
    • acknowledgeMessage
    • checkToken
    • cleanup
    • connect
    • disconnect
    • getAllMessagesToSend
    • isDuplicateQos2message
    • onPubrel
    • persist
    • publishMessage
    • restoreFromFile
    • setWill
    • subscribe
    • unsubscribe

Meta

File	connections.js
Abstract	Manages connections of the yaha Mqtt broker and provides functionality to receive/send messages from/to the managed connections in three service levels ( qos 0 , 1 , 2 )
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 .

Class Connections

new Connections(configuration)

Creates a connection object This class is part of an MQTT style broker . It manages connections to the broker .

Connections Parameters

Name	Type	Description
configuration	Object	configuration

configuration properties

Name	Type	Attribute	Default	Description
fileName	string			filename for persistence
directory	string			directory ( file path ) for persistence
replyTimeoutInMilliseconds	nubmber	optional	10000	timeout to wait for an answer of a http call
inFlightWindow	number	optional	1	amount of qos 1 and qos 2 messages send for the same topic at the same time
pubrelTimeoutInMilliseconds	number	optional	24*3600*1000	timout to wait for a corresponding pubrel message , default one day
maxRetryCount	number	optional	10	amount of resend of messages before forcing a disconnect
maxQueuSize	number			maximal amount of entries in a message queue

Connections Methods

acknowledgeMessage

acknowledgeMessage (queueEntry)

Acknowledges a message ( qos = 1 or 2 only )

acknowledgeMessage Parameters

Name	Type	Description
queueEntry	MessageQueueEntry	entry of message queue acknowledged

checkToken

checkToken (token) => {string, undefined}

Checks , if a token corresponds to a client . Returns the client

checkToken Parameters

Name	Type
token	string

checkToken throws

Type	Description
string	error message

checkToken returns

Type	Description
string, undefined	clientId .

cleanup

cleanup () => {Object}

Clean up jobs . Call regularly ( example once a minute ) Automatically disconnects clients not sending data until timeout

cleanup returns

Type	Description
Object	list of clientId beeing automatically disconnected . An object with reason : string and keepAlive : number is included for each disconnected clientId

connect

connect (clientId, host, port, clean, version, keepAlive) => {Object}

Connects a client ( Stores a connection to a client )

connect Parameters

Name	Type	Attribute	Default	Description
clientId	any			id of the client
host	string			host name
port	string			port name
clean	bool			true , if the connection will be cleaned on disconnect
version	string	optional	'1 . 0'	client interface version
keepAlive	number	optional	3600000	keep alive time in milliseconds . The broker will disconnect any client not sending messages in the keepAlive interval . Default is one hour

connect throws

Type	Description
Error

connect returns

Type	Description
Object	{ mqttcode , present } present = = 1 , if an old session is recovered

disconnect

disconnect (clientId)

Disconnects a client

disconnect Parameters

Name	Type	Description
clientId	string	id of the client

disconnect throws

Type	Description
Error

getAllMessagesToSend

getAllMessagesToSend () => {integer}

Gets all messages to send for all clients function to be called for each message . The function has the parameter QoS and message

getAllMessagesToSend returns

Type	Description
integer	amount of messages sent

isDuplicateQos2message

isDuplicateQos2message (clientId, topic, qos, dup, packetid)

Checks and remembers a qos2 message . Returns true , if the message is a duplicate

isDuplicateQos2message Parameters

Name	Type	Description
clientId	string	id of the client
topic	string	topic sent
qos	Object	quality of service received from published headers
dup	boolean	true , if the message is a duplicate
packetid	string	id of the sender package

onPubrel

onPubrel (token, packetid)

Handles a pubrel message , deleting the entry from the qos2 queue

onPubrel Parameters

Name	Type	Description
token	string	client send token
packetid	number	unique identifier of the corresponding publish packet

persist

async persist ()

Persists all connections

publishMessage

publishMessage (payload, qos, retain)

Adds messages that needs to be published

publishMessage Parameters

Name	Type	Description
payload	Message	message to add to a publish storage
qos	Object	quality of service received from published headers
retain	boolean	true , if the message should be retained for future subscribers

restoreFromFile

async restoreFromFile ()

Restores all clients from last valid saved file

setWill

setWill (clientId, will)

Sets the will message of a client

setWill Parameters

Name	Type	Description
clientId	string	id of the client
will	Object	will message configuration

will properties

Name	Type	Description
qos	number	will message quality of service
retain	boolean	true , if the will message is retained
topic	string	topic of the will message
value	string, number	value of the will message

subscribe

subscribe (clientId, topics) => {Array.<number>}

Subscribes to topics

subscribe Parameters

Name	Type	Description
clientId	string	id of the client
topics	Object	{ QoS , topics } or { topic1 : QoS1 , topic2 : QoS2 , . . . }

subscribe returns

Type	Description
Array.<number>	array of QoS values

unsubscribe

unsubscribe (clientId, topics)

Unsubsribes to topics

unsubscribe Parameters

Name	Type	Description
clientId	string	id of the client
topics	Array.<string>	array of topics strings ( topic with wildchars '+' and '#' )