EHLLAPI, COM and .NET

Everything goes through WND Terminal’s automation API, so its protections hold. Password fields read as blanks, card numbers and IT’s patterns are masked, AllowCopy = false stops programs reading the screen, and programs never see what the person types. Each program that connects is in the audit log by name, such as EHLLAPI in claims.exe or COM automation in EXCEL.EXE. AllowAutomation = false turns all of it off.

Turn it on at install

The MSI installs the DLLs with the app, in C:\Program Files\WND Terminal\compat\x86 and compat\x64. On their own they change nothing. Three MSI properties put them to use.

msiexec /i WND-Terminal-Windows.msi /qn HLLAPIFOLDER32="C:\Apps\Claims" COMPATCOM="extra wnd"

Another vendor’s files and registrations are never touched. A DLL of the same name that isn’t WND Terminal’s is left where it is, and the installer log says so. A COM name another product still has registered stays with that product, so both can be installed while people move over. Uninstalling WND Terminal removes exactly what it copied and registered, and an upgrade keeps them. The copies and registrations are in the audit log (compat.install, compat.uninstall).

To do the same after installing, from a deployment script run as an administrator:

wnd-terminal --compat-install --hllapi32 "C:\Apps\Claims" --com "pcomm"
wnd-terminal --compat-uninstall

Add --user to register the COM objects for the person running it, with no administrator rights. That’s how to use them with the per-user setup.exe.

EHLLAPI

Programs call hllapi(&function, data, &length, &rc) as they do with PCOMM, Extra! or Reflection, or WinHLLAPI with WinHLLAPIStartup. The 32-bit DLL is __stdcall, as Visual Basic’s Declare needs. Sessions are WND Terminal’s short names, A, B, C and on, in the order they opened. The status line shows “Session A”.

Text is passed in Windows code page 1252, one byte per screen position. If WND Terminal isn’t running, functions return 1, and the DLL connects again by itself once it is.

COM objects

' Extra!
Set Sys = CreateObject("EXTRA.System")
Set Screen = Sys.ActiveSession.Screen
Screen.WaitForString "Logon ===>"
Screen.SendKeys "LOGON wnduser<Enter>"

' Personal Communications
Set PS = CreateObject("PCOMM.autECLPS")
PS.SetConnectionByName "A"
PS.WaitForString "READY", 0, 0, 10000
PS.SendKeys "CADD[enter]"

' Reflection for IBM
Set R = CreateObject("ReflectionIBM.Session")
R.Transmit "wnduser"
R.TransmitTerminalKey "rcIBMEnterKey"

The objects are late bound, so VBScript, VBA with Dim x As Object and .NET dynamic find members by name. Reflection’s key constants come from its type library, so TransmitTerminalKey takes the constant’s name as text. A program bound early to a vendor’s type library, by CLSID or a VBA reference, needs that reference changed to late binding.

.NET

WndTerminal.Automation has no dependencies and works from .NET Framework 4.6.1 and later, which covers UiPath and Power Automate Desktop.

using WndTerminal.Automation;

using (var wnd = WndTerminalClient.Connect("Claims robot"))
{
    var a = wnd.Session("A");
    a.WaitForText("Logon ===>", 20);
    a.SendKeys("wnduser" + Keys.Enter);
    a.WaitReady(20);
    Console.WriteLine(a.GetText(2, 1, 5));
}

What isn’t included

• Keystroke intercept (functions 50 to 53). Programs can’t see what the person types.
• EHLLAPI file transfer (functions 90 and 91). WND Terminal does IND$FILE and FTP, FTPS and SFTP itself.
• WinHLLAPIAsync and PCOMM’s enhanced EHLLAPI structures. The standard interface only.
• OHIO, IBM’s Java Open Host Interface Objects. Java programs can use the automation API directly.