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WinHLLAPI Windows High Level Language Application Programming Interface. Windows HLLAPI (WinHLLAPI) is based on IBM's EHLLAPI specification. WinHLLAPI includes the EHLLAPI facilities and also includes Windows-specific extensions that allow the programmer to take advantage of the message-driven nature of Windows. WinHLLAPI is part of Microsoft's Windows Open Systems Architecture (WOSA). The current WinHLLAPI specification is version 1.1. This specification was developed in 1993 by Microsoft Corporation, Digital Communications Associates, Inc., Attachmate Corporation, Wall Data Incorporated, Synapse Communications, and NetSoft.
EHLLAPI Extended High Level Language Application Programming Interface.  An extension to HLLAPI.
HLLAPI High Level Language Application Programming Interface.  Was the original terminal emulator interface developed by IBM in the 1980's. This interface was designed to allow user-written applications to send data to and receive data from a terminal emulator. The term "screen-scraping" was often used to describe reading data from the terminal screen using HLLAPI. 


The purpose of WinHLLAPI is to allow applications to communicate with a host computer much like a user at a 3270, 5250 or VT100 terminal. TN3270 Plus provides the connection and communication with the host computer.  Your application can send commands to the host computer and receive data back from the host computer all via WinHLLAPI. Here are some applications for WinHLLAPI. 

  • Automate connection and logon procedures.
  • Allow unattended file transfer or data processing during off hours.
  • Combine data from multiple hosts.
  • Develop customized user interfaces for zSeries (mainframe) applications.

TN3270 Plus WinHLLAPI supports most of the functions in the Windows HLLAPI Version 1.1 specification. See WinHLLAPI Unsupported Functions in the TN3270 Plus Help file for a list of functions that TN3270 Plus does not support.

How WinHLLAPI Works

Your application needs to load the Whllapi.dll distributed with TN3270 Plus. Once this is done, your application may call the Whllapi.dll functions to send data to, or receive data from, the host computer. Whllapi.dll is an extension of TN3270 Plus and it uses TN3270 Plus to send data to, or receive data from, the host computer.

Sample Programs

Sample WinHLLAPI programs can be found on our customer downloads page.

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