Platforms to show: All Mac Windows Linux Cross-Platform
Required plugins for this example: MBS CURL Plugin
Last modified Sun, 26th Jul 2025.
You find this example project in your MBS Xojo Plugin download as a Xojo project file within the examples folder: /CURL/MQTT
Download this example: MQTT.zip
Project "MQTT.xojo_binary_project"
Class App Inherits DesktopApplication
Const kEditClear = "&Delete"
Const kFileQuit = "&Quit"
Const kFileQuitShortcut = ""
End Class
Class MainWindow Inherits DesktopWindow
Control URLField Inherits DesktopTextField
ControlInstance URLField Inherits DesktopTextField
EventHandler Sub TextChanged()
ConnectButton.Enabled = URLField.Text.Length > 0
End EventHandler
End Control
Control ConnectButton Inherits DesktopButton
ControlInstance ConnectButton Inherits DesktopButton
EventHandler Sub Pressed()
Var c As New CURLReceiveMQTT
c.OptionURL = URLField.Text
c.OptionConnectionTimeout = 5
c.OptionTCPKeepAlive = True
// ping server every 30 seconds to keep connection alive
c.OptionUpkeepIntervalMS = 30000
curl = c
// this runs asynchron in background and calls Write event when needed
Call CURLSMultiMBS.SharedInstance.AddCURL(C)
End EventHandler
End Control
Control PayloadField Inherits DesktopTextField
ControlInstance PayloadField Inherits DesktopTextField
EventHandler Sub TextChanged()
SendButton.Enabled = Me.Text.Length > 0
End EventHandler
End Control
Control SendButton Inherits DesktopButton
ControlInstance SendButton Inherits DesktopButton
EventHandler Sub Pressed()
Me.Enabled = False
var c As New CURLSMBS
c.OptionURL = URLField.Text
c.OptionPostFields = PayloadField.Text
var e As Integer = c.Perform
var debugLog As String = c.DebugMessages.ReplaceLineEndings(EndOfLine)
var Output As String = c.OutputData
If e = 0 Then
List.AddRow "Sent."
PayloadField.Text = ""
Else
var LasterrorMessage As String = c.LasterrorMessage
List.AddRow "Sent failed: "+LasterrorMessage
Break
MessageBox "Failed to send with error " + e.ToString + EndOfLine+EndOfLine + LasterrorMessage
End If
End EventHandler
End Control
Control List Inherits DesktopListBox
ControlInstance List Inherits DesktopListBox
End Control
Control Timer1 Inherits Timer
ControlInstance Timer1 Inherits Timer
EventHandler Sub Action()
Dim d As DateTime = DateTime.Now
List.AddRow str(d.SecondsFrom1970-start.SecondsFrom1970, "0.0")+" seconds"
End EventHandler
End Control
EventHandler Sub Opening()
Start = DateTime.now
End EventHandler
Property Start As datetime
Property curl As CURLReceiveMQTT
End Class
MenuBar MainMenuBar
MenuItem FileMenu = "&File"
MenuItem FileQuit = "#App.kFileQuit"
MenuItem EditMenu = "&Edit"
MenuItem EditUndo = "&Undo"
MenuItem EditSeparator1 = "-"
MenuItem EditCut = "Cu&t"
MenuItem EditCopy = "&Copy"
MenuItem EditPaste = "&Paste"
MenuItem EditClear = "#App.kEditClear"
MenuItem EditSeparator2 = "-"
MenuItem EditSelectAll = "Select &All"
MenuItem HelpMenu = "&Help"
End MenuBar
Sign
End Sign
Class CURLReceiveMQTT Inherits CURLSMBS
EventHandler Sub Finished(Result as Integer)
#Pragma BackgroundTasks False
System.DebugLog CurrentMethodName +": "+result.ToString
Var LastErrorMessage As String = Me.LasterrorMessage
var debugLog As String = Me.DebugMessages.ReplaceLineEndings(EndOfLine)
Var Output As String = Me.OutputData
MainWindow.List.AddRow "Finished: "+result.ToString
End EventHandler
EventHandler Function Write(data as string, dataSize as Integer) As integer
#Pragma BackgroundTasks False
// we received data!
System.DebugLog CurrentMethodName
// first two bytes are length, then channel and content
Var m As MemoryBlock = data
m.LittleEndian = False
Var l As Integer = m.Int16Value(0)
Var c As String = MidB(data, 3, l)
Var d As String = MidB(data, 3 + l)
MainWindow.List.AddRow "Received: "+c+" "+d
Return dataSize
End EventHandler
End Class
End Project
Download this example: MQTT.zip
The items on this page are in the following plugins: MBS CURL Plugin.
