Windows Considerations

This section summarizes information for developing LUA applications on a Microsoft® Windows® version 3.x system.

Load-time linking

To be dynamically linked to LUA at load time, you must do one of the following at link time:

• Insert the following IMPORTS statements in the definition (.DEF) file used to link the application:

  (For RUI)

  IMPORTS WINRUI.RUI
  IMPORTS WINRUI WinRUI
  IMPORTS WINRUI.WinRUIStartup
  IMPORTS WINRUI.WinRUICleanup
   

  (For SLI)

  IMPORTS WINSLI.SLI
  IMPORTS WINSLI.WinSLI
  IMPORTS WINSLI.WinSLIStartup
  IMPORTS WINSLI.WinSLICleanup
   

• Link the application to WINRUI.LIB (for RUI) or WINSLI.LIB (for SLI), which contain the entry-point linkage information.

Packing

VCBs are not packed. As a result, DWORDs and WORDs are on WORD boundaries and BYTEs are on BYTE boundaries. This means, for example, that there is not a 2-byte gap between the primary and secondary return codes. VCBs should be accessed using the structures provided, and compiler options that change this packing method should be avoided.

Registering and deregistering applications

All Windows LUA applications must call the Windows SNA extension function WinRUIStartup or WinSLIStartup at the beginning of the session to register the application and WinRUICleanup or WinSLICleanup at the end of the session to deregister the application.

Run-time linking

For an application to be dynamically linked to LUA at run time, it must issue the following calls:

• Call the LoadLibrary function to dynamically load the WINRUI.DLL (for RUI) or WINSLI.DLL (for SLI) library module for Windows LUA.
• Call the GetProcAddress function to retrieve the address of each LUA function entry point that will be called in the DLL. For RUI, the function entry points are RUI, WinRUI, WinRUIStartup, and WinRUICleanup. For SLI, the function entry points are SLI, WinSLI, WinSLIStartup, and WinSLICleanup.

Simultaneous sessions

An application can participate in as many as 16 sessions simultaneously in the Windows environment. However, if multiple LUA applications are active at the same time, the total number of sessions cannot exceed 16.