VB 6.0 can use MQTT

Some time ago, I undertook a project, software development, time is tight, so I used VB to deduct one. Later, the user proposed to transmit the data to their MQTT server for distribution, and used the VB 6.0 code for a few days to get a VB 6.0 program that can communicate with the MQTT Broker.

In order to support other people's rapid development and use. A program with Socket communication port is made.
Insert picture description here
MQTT Client for VB 6 service program

All codes are written in VB6.0.

Four API functions
Sleep
Shell_NotifyIcon
SendMessage
GetPrivateProfileString are called. The
first three are to make a tray icon, and the latter is to read and write the configured INI file.
Use Winsocket control, Timer control, Textbox control, Frame control, Label control.
There are no third-party controls.
There are no third-party controls.
There are no third-party controls.
The main interface is as follows:

Insert picture description here
Note: The MQTT Broker port we tested by ourselves is 1884, while the conventional MQTT Broker port is 1883. After the
software is running, the interface

Insert picture description here
The program usually exists as a tray icon

Insert picture description here
The icon is also drawn by myself.

Development idea: Developed in the session layer of the OSI 7-layer protocol. It is SOCKET programming.

The user-developed VB program uses TCP SOCKET to communicate with the MQTT Client for VB 6, and transmits a specific message structure through the socket, and then it can send Topic to MQTT Broker, subscribe to the Topic, and accept the content of the subscribed Topic.

On Error Resume Next
  Dim INIFileName As String
  Dim MQTTServerIP As String
  Dim MQTTServerPort As Long
  Dim SocketServerPort As Long
  Dim i As Long
  
  '初始化页面代码
  Me.TextFasong = ""
  Me.TextNeiRongD = ""
  Me.ListDingYue.Clear
  Me.Label1.Caption = "接收的数据"
  Me.Label2.Caption = "发送的数据"
  Me.Label3.Caption = "订阅的主题"
  Caption = "MQTT Client for VB6 服务程序"
  '启动后，缩小为图标
  Me.WindowState = vbMinimized
  If WindowState = vbMinimized Then
    LastState = vbNormal
  Else
    LastState = WindowState
  End If
  With mydata
    .cbSize = Len(mydata)
    .hwnd = Me.hwnd
    .uID = 0
    .uFlags = NIF_ICON Or NIF_MESSAGE Or NIF_TIP
    .uCallbackMessage = WM_MOUSEMOVE
    .hIcon = Me.Icon.Handle '默认为窗口图标
    .szTip = "MQTT client for VB6 服务程序" & vbNullChar
  End With
  Shell_NotifyIcon NIM_ADD, mydata
  
  
  '读取配置文件打开MQTT链接
  INIFileName = FormatFileName("config.ini")
  MQTTServerIP = ReadINI("MQTTBroker", "BrokerADD ", INIFileName)
  MQTTServerPort = Val(ReadINI("MQTTBroker", "BrokerPort", INIFileName))
  MQTTpublisherName = ReadINI("MQTTBroker", "MQTTpublisherName", INIFileName)
  
  MQTTTopicquantity = Val(ReadINI("MQTTBroker", "Topicquantity", INIFileName))
  MQTTPublish = ReadINI("MQTTBroker", "MQTTPublish", INIFileName)
  For i = 0 To MQTTTopicquantity - 1
    MQTTTopic(i) = ReadINI("MQTTBroker", "Topic" & i + 1, INIFileName)
    Me.ListDingYue.AddItem MQTTTopic(i), 0
  Next i
  
  'MQTT Socket 初始化
    Me.LabelMQTTBrokerName = "MQTT Broker:" & MQTTServerIP
  Me.LabelMQTTPort = "MQTT Broker Port:" & MQTTServerPort
  Me.LabelMQTTpublisher = "MQTT publisher:" & MQTTpublisherName
  MQTTBrokerFlag = True
  WinsockMQTT.RemoteHost = MQTTServerIP
  WinsockMQTT.RemotePort = MQTTServerPort
  WinsockMQTT.Protocol = sckTCPProtocol
  TimerMQTTState.Enabled = True
  MQTTFlag = False
  If WinsockMQTT.State = 0 And MQTTBrokerFlag Then
    WinsockMQTT.Connect
  End If
  
  'SocketServer 初始化
  SocketServerPort = ReadINI("SocketServer", "SocketServerPort", INIFileName)
  Me.TimerServerState.Enabled = True
  If SocketServerPort >= 1000 Then
    WinsockServer.LocalPort = SocketServerPort
    WinsockServer.Protocol = sckTCPProtocol
    WinsockServer.Listen
    Me.LabelSocketServerPort = "Socket Server Port:" & SocketServerPort
  End If
  
End Sub

This is the code initiated by the main From.

The biggest difficulty in developing this is that the message structure in the MQTT protocol is very special and requires a lot of conversion work.

It took 5 days to write about it, about 30 hours.

For the time being, this MQTT Client for VB 6 can only communicate with servers based on MQTT 3.1.1, such as Mobile OneNet, Alibaba Cloud, and Tencent Cloud. Our own projects are run by Huawei Cloud.

When you have time, you can add encryption to support MQTT Broker for encrypted transmission.

Those who are interested, we can discuss together.

Guess you like