Introduction

Emulator High-level Language Application Program Interface (EHLLAPI) standard and API was introduced by IBM for IBM 3270 & 5250 servers, allowing client applications to access information on the host screen. IBM EHLLAPI standard is supported by most of the Terminal Emulator solutions and forms the basis for many enterprise automation suites and application customization.
Below blogs show different automation capabilities available in IBM Personal Communications.
https://community.ibm.com/community/user/ibmz-and-linuxone/blogs/mahua-chanda/2021/08/31/emulator-high-level-language-api-ehllapi-in-ibm-pe
https://community.ibm.com/community/user/ibmz-and-linuxone/blogs/mahua-chanda/2021/08/31/personal-communications-session-api-pcsapi-in-ibm

IBM Host On-Demand (HOD in short) is another terminal emulator from IBM, which is highly popular for being platform independent, browser based, and having central administration capabilities. HOD supports various automation features, one of which is the capability to interact with EHLLAPI applications.
Following type of EHLLAPI applications can be used via this bridge:
a.       IBM standard interfaces support

• Industry Standard EHLLAPI
• IBM Enhanced EHLLAPI
• Win HLLAPII
• DOS HLLAPI

b.       Non-Standard IBM interfaces supported
IBM Personal Communications PCSAPI Interface

This blog provides more details on this bridge and how to use an EHLLAPI application written for IBM PCOMM on IBM HOD using the EHLLAPI Bridge.

Download Instructions

This tool can be downloaded from IBM Fix Central.

• Enter “IBM Host On-Demand”
• Pick the Installed HOD version details, platform (windows only) & click on Submit
• On the "Identify Fixes" page, search and select 'HOD_xxxx_EHLLAPI_Library '.
• Click Continue to download the EHLLAPI bridge.
• For 32-bit Automation application (e.g. Excel) and 32-bit HOD use 'ehllapi_x86.exe'
• For 64-bit Automation application (e.g. Excel) and 64-bit HOD use 'ehllapi_x64.exe'
• The Ehllapi bridge must be installed in the client system where you have the Automation application (e.g. Excel) and HOD client.

High Level Control Flow

1.       Enable EHLLAPI Bridge in HOD Session profile.
2.       Launch HOD with the modified session profile.
3.       HOD invokes EHLLAPI bridge and establishes a connection with it.
4.       HOD connects with the host specified in the session profile.
5.       Execute the EHLLAPI Application. When run, EHLLAPI functions are executed on the HOD session rather than PCOMM. Refer to the following design.

Below is a sample on how to configure EHLLAPI and how to use it from IBM Host on Demand

1.       Launch HOD user console.
2.       Select the desired profile and select ‘properties’ from the context menu.
3.       Go to ‘Start Options’ on the left pane and Select the ‘Yes’ radio button of ‘Auto-Start’ HLLAPI Enable.
4.       Click Ok to apply changes.
Note: this invokes EHLLAPI bridge when the selected HOD session is launched.
5.       Launch ‘5250 Display’ session.
          For this example, we have launched Session ‘A’ to a 5250 Host.
6.       Verify that the EHLLAPI bridge is launched correctly by clicking ‘Java Console’ Button on HOD User console.
7.       Verify that the Java Console displays the following text.
                      “
                       IBM Host Access Class Library
                       Version:  XX.0.1-B20161206
                       Copyright IBM Corporation 1997, 201X. All rights reserved.
 
                       Using EHLLAPI: XX.00-050116
                       ”
Where, XX is replaced with the appropriate HOD Version number.
8.       Launch the attached sample program ‘EHLLAPI_Bridge_Sample.xls’ to perform appropriate operations. You can observe that the EHLLAPI application can connect, read or write data to/from the HOD Terminal Emulator Screen.
Note: More detailed scenarios can be found in the sample EHLLAPI application shipped with PCOMM. It can be found at the following location: <PCOMM_InstallDir>\PCOMM\Samples\VBHLLAPI

If you already have an existing PCOMM EHLLAPI application, it can be executed to communicate with a HOD session using EHLLAPI Bridge (using the procedure above), without needing any modifications.

​Troubleshooting
We have seen some issues when EHLLAPI bridge is installed on the same system as IBM Personal Communications. This is due to existence of multiple versions of the same library being present on the client system.
 
Please refer to the link below to understand how to resolve/workaround these issues
https://www-01.ibm.com/support/docview.wss?uid=ibm10725431

Download the Sample code:
ehllapi_bridge_sample.xls
Note: When using 64-bit Excel, add 'PtrSafe' attribute in the function declaration as below:
Declare Function PCOMM_SendKey& Lib "PCSHLL32.DLL" Alias "hllapi" (HllFunctionNo&, ByVal HllData$, HllLength&, HllReturnCode&)

Contact:
For further information on Automation, Services Offerings or Technical details in IBM HACP/HATS please connect with HCL mainframe Lab Services.

Avinash Sable
Lead - Lab Services, IBM HACP & HATS