mqtt.publish() function

mqtt.publish() sends data to an MQTT broker using MQTT protocol.

Function type signature

(
    broker: string,
    message: string,
    topic: string,
    ?clientid: string,
    ?password: string,
    ?qos: int,
    ?retain: bool,
    ?timeout: duration,
    ?username: string,
) => bool

Parameters

broker

(Required) MQTT broker connection string.

topic

(Required) MQTT topic to send data to.

message

(Required) Message to send to the MQTT broker.

qos

MQTT Quality of Service (QoS) level. Values range from [0-2]. Default is 0.

retain

MQTT retain flag. Default is false.

clientid

MQTT client ID.

username

Username to send to the MQTT broker.

Username is only required if the broker requires authentication. If you provide a username, you must provide a password.

password

Password to send to the MQTT broker.

Password is only required if the broker requires authentication. If you provide a password, you must provide a username.

timeout

MQTT connection timeout. Default is 1s.

Examples

• Send a message to an MQTT endpoint
• Send a message to an MQTT endpoint using input data

Send a message to an MQTT endpoint

import "experimental/mqtt"

mqtt.publish(
    broker: "tcp://localhost:8883",
    topic: "alerts",
    message: "wake up",
    clientid: "alert-watcher",
    retain: true,
)

Send a message to an MQTT endpoint using input data

import "experimental/mqtt"
import "sampledata"

sampledata.float()
    |> map(
        fn: (r) =>
            ({r with sent:
                    mqtt.publish(
                        broker: "tcp://localhost:8883",
                        topic: "sampledata/${r.id}",
                        message: string(v: r._value),
                        clientid: "sensor-12a4",
                    ),
            }),
    )