B4J Tutorial [BANano] BANanoMQTT with HiveMQ Cloud

Hi Fam

Ensure you create credentials to login to your HiveMQ account.

You get your TSL WebSocket URL which is like..

104bbaaaa07a4293456e659cf91023.s1.eu.hivemq.cloud:8884/mqtt

Split these into various variables (done for brevity)

"MQTTPort": 8884,
    "MQTTUser": "ssssss",
    "MQTTPwd": "sssss",
    "MQTTHost": "104bbaaaa07a4293456e659cf91023.s1.eu.hivemq.cloud:",
    "MQTTPath": "/mqtt"

Code to connect

Sub StartMQTT
    MQTTConnected = False
    MQTTConnect
End Sub

Code to Connect to HiveMQ

Sub MQTTConnect
    Log("MQTT - ConnectAndReconnect...")
    MQTTWorking = True
    MQTTTimer.Initialize("MQTTTimer", 5000) ' Timer checks every 5 seconds
    MQTTTimer.Enabled = True

    mqtt.Initialize("mqtt", MQTTHost, MQTTPort, MQTTPath, True, MQTTClientID)
    Dim ops As BANanoMQTTConnectOptions
    ops.Initialize(MQTTUser, MQTTPwd)
    ops.CleanSession = False
    ops.As(BANanoObject).SetField("keepAliveInterval", 60)
'    ops.SetLastWill("connected", "N".GetBytes("UTF8"), 0, False)
    mqtt.Connect2(ops)
End Sub

Code to fire when Connected (Still testing the ping stuff)

Sub mqtt_Connected (Success As Boolean)
    If Success Then
        Log("Client: Mqtt connected")
        MQTTConnected = True ' Mark the connection as established
        MQTTTimer.Enabled = False ' Disable the timer once connected
       

        mqtt.Subscribe("xxxx/#", 2)
       
        ' Start periodic ping while connected
        Do While MQTTWorking And MQTTConnected
            mqtt.Publish2("ping", "A".GetBytes("UTF-8"), 2, False)
            Sleep(60000) ' Ping every 1 minute
        Loop
    Else
        MQTTPublish("connected", "N")
        Log("Client: Could not connect to MQTT broker!")
        MQTTConnected = False
        MQTTTimer.Enabled = True
        Log(LastException.message)
    End If
End Sub

Timer That Fires when a disconnection event happens

' Timer event for periodic checks
Sub MQTTTimer_Tick
    If Not(MQTTConnected) Then
        Log("MQTT disconnected, attempting to reconnect...")
        ' Attempt to reconnect
        MQTTConnect
    End If
End Sub

Code to Fire when disconnected

private Sub mqtt_Disconnected
    MQTTConnected = False
    MQTTTimer.Enabled = True
    Try
        conversations.Offline
'        App.ShowToastSuccess("Disconnected to MQTT Broker!")
    Catch
    End Try                'ignore
End Sub

Trapping Arriving Messages

Private Sub mqtt_MessageArrived (Topic As String, Payload() As Byte)
    Log("Client: mqtt_MessageArrived")
    Log($"Topic: ${Topic}"$)
   
    'ignore topics comings to myself
    If Topic = MQTTTopic1 Then Return
    'continue processing
    Dim msg As String = BytesToString(Payload, 0, Payload.Length, "utf8")
   
    If Topic.StartsWith("chats") Then
        DoWhatEver
    End If
.....