Subscribe via trigger

Kees Schollaart edited this page Apr 16, 2018 · 5 revisions

Trigger Binding

  • Add the MqttTriggerAttribute to one of your functions parameters
  • Use one of the constructor overloads to configure
    • The first/simple constructor only requires one or more topic-names (eg: "my/topic/#")
    • The second (more advanced) constructor requires a Type which you then have to implement more on this
  • Make sure the type of the parameter is IMqttMessage


This an example of a Function triggered by messages published on the "testtopic/in" topic using the simple constructor:

public static void SimpleFunction(
        [MqttTrigger("testtopic/in")]IMqttMessage message,
        ILogger logger)
        var body = message.GetMessage();
        var bodyString = Encoding.UTF8.GetString(body);
        logger.LogInformation($"{DateTime.Now:g} Message for topic {message.Topic}: {bodyString}");


The connection to the MQTT broker is made when the function boots. Connections can only be used by one MqttTrigger. It is possible to reuse connections for outputs/publishing messages.

Internally the MQTT connection is managed by MQTTNet's Managed Client.

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