public TestService()
{
    InitializeComponent();
    CanShutdown = true;
}

protected override void OnStart(string[] args)
{
    try
    {
        YourRequestMethod(true);
    }
    catch (Exception ex)
    {
        System.Windows.Forms.MessageBox.Show(ex.Message);
    }
}

protected override void OnShutdown()
{
    try
    {
        YourRequestMethod(false);
    }
    catch (Exception ex)
    {
         System.Windows.Forms.MessageBox.Show(ex.Message);
    }
    base.OnShutdown();
}

private static void YourRequestMethod(bool flag)
{
    if(flag)
    {
        // Your GET request to ON
    }
    else
    {
        // Your GET request to OFF
    }
}

Dir & Echo too

Dir && Echo too

setlocal EnableDelayedExpansion && set MyVar=MyVal && echo !MyVar! && endlocal

;==============================
;Set the path to your batch file.
path    := "C:\batch.bat"
;==============================

; Run script as admin. This will allow your batch file to be ran with admin priv.
if not A_IsAdmin
{
   Run *RunAs "%A_ScriptFullPath%"  ; Requires v1.0.92.01+
   ExitApp
}

; Only allow one instance of the script to run.
#SingleInstance, Force

; If you don't want an icon to show in the tray,
; remove the semicolon from the line below.
;#NoTrayIcon

; When script detects WM_QUERYENDSESSION (a shutdown), run OnShutDown function.
OnMessage(0x11, "OnShutDown")
return

OnShutDown(){
    ; Run the batch file.
    Run, % path
    ExitApp
}

%windir%\System32\rundll32.exe powrprof.dll,SetSuspendState Standby