Publish a message

Private Sub Publish()
On Error GoTo errExit
    Dim retCode As MqttPublishCode
    Dim msg As MQTTMessage
    Dim data() As Byte
    
    Set msg = mFactory.CreateApplicationMessage()
    msg.PayloadFormat = MqttPayloadCharacter
    msg.Topic = "SE"
    msg.payload = "This is the payload."
    msg.QoS = MqttQoS2
    
    ' Configure more advanced MQTT properties, which are not necessary configurations. Configure them as needed.
    msg.SubscriptionIdentifiers = CLng(5)
    msg.contenttype = "String"
    data = StrConv("This is the correlation data.", vbFromUnicode)
    msg.correlation = data
    msg.ResponseTopic = "This is the response topic."
    msg.AddUserProperty "Key1", "Value1"
    msg.AddUserProperty "Key2", "Value2"
    
    retCode = mClient.Publish(msg)
    Exit Sub
    
errExit:
    MsgBox err.Description
End Sub