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 '#' ) | |