Abstract

Library module to communicate with the mqtt broker . It includes Publish to send messsages to the broker and OnPublish to receive messages published by the broker

Contents

• Meta
• Class OnPublish
  • Parameters
  • Members
  • Methods
    • close
    • listen
    • on
• Class PublishMessage
  • Parameters
  • Methods
    • close
    • publish

Meta

| | | | --- | --- | | File | mqttservice.js | | Abstract | Library module to communicate with the mqtt broker . It includes Publish to send messsages to the broker and OnPublish to receive messages published by the 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 . |

Callback definitions

ProcessMessage

ProcessMessage Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | message | Object | the message received | | | qos | 0, 1, 2 | the quality of service information | | | dup | 0, 1 | flag signaling duplicates | |

Class OnPublish

new OnPublish(listenerPort, logSettings, qos2PubrelTimeoutInSeconds)

Creates a new server receiving messages Supports registering a callback with on ( 'publish' , ( payload , qos ) = > { } ) called for each received message

OnPublish Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | listenerPort | number | port to listen on | | | logSettings | Object | logging settings | | | qos2PubrelTimeoutInSeconds | number | time to delete qos2 related packageid´s from the qos2 queue . This will happen , if a pubrel does not follow the publish call for a this amount of seconds | |

OnPublish Members

| Name | Type | description | | ------------ | ------------ | ------------ | | logFilter | LogFilter | Logging filter | | port | number | Port the server uses , only defined after listen has been called ! |

OnPublish Methods

close

close ()

Closes all connections

listen

listen ()

Starts to listen and wait for input

on

on (event, callback)

Sets a callback . Usually , there is no need to set anything here

on Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | event | string | event name , supported 'publish' | | | callback | ProcessMessage | callback to be called , to process messages received | |

Class PublishMessage

new PublishMessage(host, port, configuration)

Creates a client for publishing messages

Example

//Publish the message with topic /a/a, value 1, reason "test", QoS 0, retain 0:
const publish = new PublishMessage('myhost', 10000, { retry: 60 })
result = await publish.publish(publishtoken, new Message("/a/a", 1, "test"), 0, 0);

PublishMessage Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | host | string | host name ( or ip ) | | | port | number | port number | | | configuration | Object | configuration options | |

configuration properties

| Name | Type | Attribute | Default | Description | | ---------- | ------------ | ------------ | ------------ | ----------------- | | retry | number | optional | 60 | amount of retries to send a message | |

PublishMessage Methods

close

async close ()

Closes the connection to the broker

publish

async publish (token, message, qos, retain, version)

Publishes a message with a defined quality of service automatically generating an id

publish Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | token | string | connection token | | | message | Object | message to publish . | | | qos | number | 0 , 1 , 2 quality of service | | | retain | boolean | True , if message shall be retained for future subscriptions | | | version | string, undefined | interface version , supports 0 . 0 and 1 . 0 ( default ) | |

publish throws

| Type | Description | | ---- | ----------- | | string | on any connection error |