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Inbound MQTT Connector

MQTT is a publish/subscribe protocol that allows clients to listen to a stream of events produced to a server.

It is widely used in real-time and IoT applications since it is lightweight and easy to use.

 

Common config values

type: mqtt-source
version: 0.5.1
 

Parameters

The inbound MQTT connector supports the following configuration options:

 

mqtt-url

required

The hostname of the MQTT server to subscribe to

This value can be provided as a parameter or as a secret

 

mqtt-topic

required

The topic filter to use when receiving MQTT events

 

Example connector config

version: 0.5.1
name: my-mqtt
type: mqtt-source
topic: mqtt-topic
parameters:
 mqtt_topic: "/hfp/v2/journey/#"
secrets:
 MQTT_URL: mqtts://mqtt.hsl.fi:8883/
 

Data Events

There are two important pieces of information that we’re interested in capturing from every MQTT event.

  1. The topic the event was sent to
  2. The body of the event

In MQTT, topics are more of a label for particular message types. When we specify a mqtt-topic to subscribe to, we are actually defining a “filter”, or a pattern that tells MQTT which events we are interested in receiving.

This means that events we receive may not all belong to the same topic - rather, they all match the filter we provided.

The result of the event message body produced to Fluvio by the inbound MQTT connector is a JSON object containing:

  • MQTT topic name
  • MQTT message body

Furthermore, since MQTT allows events to contain arbitrary binary data, the payload is encoded as a byte buffer.

Below is a sample of what an MQTT event captured and sent to Fluvio looks like:

{"mqtt_topic":"/hfp/v2/journey/ongoing/vp/bus/0022/01151/2200/1/Espoon keskus/23:02/1160105/4/60;24/29/00/00","payload":[123,34,86,80,34,58,123,34,100,101,115,105,34,58,34,50,48,48,34,44,34,100,105,114,34,58,34,49,34,44,34,111,112,101,114,34,58,50,50,44,34,118,101,104,34,58,49,49,53,49,44,34,116,115,116,34,58,34,50,48,50,49,45,49,49,45,49,56,84,50,49,58,49,51,58,51,50,46,56,56,52,90,34,44,34,116,115,105,34,58,49,54,51,55,50,55,48,48,49,50,44,34,115,112,100,34,58,49,50,46,54,55,44,34,104,100,103,34,58,51,51,55,44,34,108,97,116,34,58,54,48,46,50,48,48,49,53,55,44,34,108,111,110,103,34,58,50,52,46,57,48,48,50,49,53,44,34,97,99,99,34,58,45,48,46,49,49,44,34,100,108,34,58,45,55,53,44,34,111,100,111,34,58,110,117,108,108,44,34,100,114,115,116,34,58,110,117,108,108,44,34,111,100,97,121,34,58,34,50,48,50,49,45,49,49,45,49,56,34,44,34,106,114,110,34,58,49,53,48,44,34,108,105,110,101,34,58,49,48,52,52,44,34,115,116,97,114,116,34,58,34,50,51,58,48,50,34,44,34,108,111,99,34,58,34,71,80,83,34,44,34,115,116,111,112,34,58,110,117,108,108,44,34,114,111,117,116,101,34,58,34,50,50,48,48,34,44,34,111,99,99,117,34,58,48,125,125]}