Abstract

The ( mqtt ) broker is a central service receiving and distributing messages to all subscribed receipiens . Use the "brokerservice" module to start the broker .

Contents

• Meta
• Class Broker
  • Parameters
  • Methods
    • close
    • connect
    • on
    • run

Meta

| | | | --- | --- | | File | broker.js | | Abstract | The ( mqtt ) broker is a central service receiving and distributing messages to all subscribed receipiens . Use the "brokerservice" module to start 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 . |

Class Broker

new Broker(configuration)

Creates a new broker

Example

const configuration = {
     port: 10000,
     persistInterval: 0,
     connections: {
          directory: '.',
          fileName: 'broker',
          log: [
              {
                  module: 'received',
                  topic: '#'
              }
          ]
      }
  }
const broker = new Broker(configuration)
broker.run()

Broker Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | configuration | Object | configuration for the broker | |

configuration properties

| Name | Type | Attribute | Default | Description | | ---------- | ------------ | ------------ | ------------ | ----------------- | | port | number, string | | | port number the broker will listen on | | | persistInterval | number | optional | 60 * 1000 | Intervall between persisting internal state to file in milliseconds . Persistance is not called if this value is 0 | | | connections | Object | | | connection settings for the broker | |

connections properties

| Name | Type | Attribute | Default | Description | | ---------- | ------------ | ------------ | ------------ | ----------------- | | fileName | string | | | filename for persistence | | | directory | string | | | directory ( file path ) for persistence | | | replyTimeoutInMilliseconds | number | | | 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 | one day | temeout to wait for a corresponding pubrel message | | | maxRetryCount | number | | | amount of resend of messages before forcing a disconnect | | | maxQueuSize | number | | | maximal amount of entries in a message queue | | | log | Object | | | log settings | |

Broker Methods

close

async close ()

Closes the broker , stops listening

connect

connect (host, port)

Connects to a friendly broker and subscribs for all messages

connect Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | host | string | name of the host ( or his ip ) | | | port | number | port number to connect to | |

on

on (event, callback)

Sets a callback .

on Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | event | string | callback name ( supports 'send' and 'publish' ) 'send' is called to send data . This function is provided by the broker but could be overwritten 'publish' is called on receiving data . This function if provided by the broker but could be overwritten | | | callback | function | | |

on throws

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

run

run ()

Starts the broker . It will listen to message , send messages and periodically store its status