Extended Support for Mainframes HOD

About IBM® Host On-Demand

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.
IBM® Host On-Demand (HOD) provides security-rich web-to-host terminal emulation and host access application programming support from a single interface It also provides connectivity to TN3270E, TN5250, VT52, VT100, VT220 and VT420 systems, IBM CICS® applications, and FTP servers. The Managed Host On-Demand environment replaces the browser on the local machine and removes the need to download the Java Runtime Environment (JRE).

HOD Automation with Avo Assure

Avo Assure can automate any region of HOD including ACT and BPST (regions), provided HOD is configurable and bridge connections are available.

Types of HOD

Following IBM Host On-Demand types are supported in Avo Assure:
  1. 1.
    ACT - uses IBM Rational HOD v11.0.8-B20130530
HOD type – ACT
2. BPST (HOD-WAM) uses IBM Rational HOD v11.0.3-B20101207
HOD type – BPST

Prerequisites: Mainframe HOD Automation



EHLLAPI stands for Emulator High-Level Language Application Program Interface., it was introduced by IBM for 3270 and 5250, to allow client applications to access the host screen. Each version of HOD has its compatible version of EHLLAPI (even though any version of EHLLAPI can be used, it's better to use a compatible version example: If v11-HOD is installed, we will use a compatible version which is EHLLAPI-v12 as it is compatible with v11 and v12 HOD).

EHLLAPI Bridge- Download

How to download the EHLLAPI bridge connector (please note in order to download you need to have a valid IBM ID, contact ITIS in this case):
  1. 1.
    Navigate to in any browser.
  2. 2.
    Enter ‘IBM EHLLAPI Library for Host On-Demand’in product selector textbox.
  3. 3.
    Pick the Installed HOD version details, platform (windows only) & click on Submit.
  4. 4.
    On the ‘Identify Fixes’ page, 'Browse for fixes' and then click ‘Continue’.
  5. 5.
    Download and install the EHLLAPI Bridge.

EHLLAPI Bridge- Install

  1. 1.
    Double-click on ehllapi.exe. The installation process will be started by an InstallShield Wizard.
  2. 2.
    In the InstallShield window, confirm installation by clicking on Next.
  3. 3.
    In the following dialog, a target directory for the installation needs to be specified. Confirm the default directory by clicking Next.
  4. 4.
    The InstallShield Wizard has all the information required for the installation. Click on Next. This starts the actual installation.
  5. 5.
    When the installation is completed successfully, click on Finish to finalize the process.

Configuration changes in HOD


Host On-Demand allows configuration changes. In order to automate HOD, we must first make create a HOD session with EHLLAPI Bridge enabled.

IBM Host On-Demand (ACT)

Below is a sample of how to configure EHLLAPI and how to use it from IBM Host On-Demand (ACT).
  1. 1.
    Open Host On-Demand (ACT).
2. Right-click on the desired HOD Session and click on the Properties option.
HOD (ACT) - Session Properties
3. On selecting the Properties option, the Properties config window appears. Click on Preferences > Start Options. Select Yes for radio control Auto-start HLLAPI Enabler.
HOD (ACT) – Properties configuration window
4. Click on the OK button. Now this HOD session is modified and will connect to an EHLLAPI bridge when available.

IBM Host On-Demand (HOD-WAM)

Below is a sample of how to configure EHLLAPI and how to use it from IBM Host On-Demand (HOD-WAM).
  1. 1.
    Navigate to the location of HOD-WAM. Navigate inside the HODDeploy folder.
HOD-WAM Folder
2. Navigate inside the HODData folder.
HODDeploy Folder
3. Open and edit file
HODData Folder
4. Set the values of startHLLAPIEnabler and startHLLAPIEnablerAdmin to true. Save and close the file. File
5. Now HOD-WAM will start with a modified session.
Note: For any available HOD session, there will be a configurable property where we can enable the HLLAPI connection. This property needs to be set to True or Yes in order to connect to the EHLLAPI bridge.

Control Flow

  1. 1.
    Enable EHLLAPI Bridge in HOD Session profile.
  2. 2.
    Launch HOD with the modified session profile.
  3. 3.
    HOD invokes EHLLAPI Bridge and establishes a connection with it.
  4. 4.
    HOD connects with the host specified in the session profile.
  5. 5.
    Execute the EHLLAPI Application. When run, EHLLAPI functions are executed on the HOD session.
  6. 6.
    This EHLLAPI app can then be automated by Avo Assure.
Control Flow


  1. 1.
    Without an EHLLAPI bridge connection, automation is not possible (unless using IRIS).
  2. 2.
    HLLAPI enabler must be set to True or Yes, otherwise the session will not connect to the EHLLAPI bridge.
  3. 3.
    If two EHLLAPI apps are open with the same ShortSessionID, then the connection is made to the first EHLLAPI app. The connection will only be made to the second app on the closure of the first. Connection is made on the ConnectSession keyword.