IPWorks MQ 2020 ActiveX Edition

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MessageIn Event

Fired when an incoming message has been received and/or fully acknowledged.


Sub mqttcontrol_MessageIn(PacketId As Integer, Topic As String, QOS As Integer, Message As String, Retained As Boolean, Duplicate As Boolean)


The MessageIn event fires once for each incoming message either immediately after it is received (QoS 0), or after it has been fully acknowledged (QoS 1 and 2).

  • PacketId: The message packet Id. This will always be -1 if QOS is 0.
  • Topic: The message's topic string.
  • QOS: The message's QoS level.
  • Message: The message data.
  • Retained: Whether or not this message was received as a result of subscribing to a topic.
  • Duplicate: Whether or not the server has indicated that this message is a duplicate of another message sent previously.

Refer to MessageAck for more information about QoS 1 and 2 message processing steps.

// MessageIn event handler.
mqtt1.OnMessageIn += (s, e) => {
  Console.WriteLine("Received message from topic '" + e.Topic + "' with QoS " + e.QOS + ":");

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IPWorks MQ 2020 ActiveX Edition - Version 20.0 [Build 8162]