HostBridge Technology


JavaScript Web Services for CICS & z/OS Mainframe Integration

HostBridge JavaScript Engine [1]

The HostBridge JavaScript Engine (HB.js) is server-side JavaScript for CICS® applications and IBM z Systems™ data assets. It is the only JavaScript/JSON-based integration solution for the mainframe. Both a development facility and runtime engine, HB.js provides all the capabilities z Systems customers need to rapidly develop and deploy reusable Web services and/or scripts that:

Capabilities and Support

Built on the ECMAScript 3/JavaScript 1.8 code base [2], the HostBridge JavaScript Engine fully supports a wide range of object-oriented scripting/Web services types and protocols, including JavaScript, JSON, XML, SOAP, SOAP 1.2, RESTful services, Ajax, Atom, HTML, and E4X (ECMAScript for XML).

HB.js runs inside CICS and supports:

For a complete listing of technologies supported by HB.js, see our HostBridge v6.5 data sheet with technical specifications.

Predefined Objects

HB.js also includes predefined program objects that can be used within a script, allowing it to perform a wide range of operations – virtually anything a COBOL program can do. Some of these predefined objects are:

HostBridge Data Access Modules for VSAM, DB2, DL/I, and Datacom integration are also predefined in HB.js. The modules are described on our Data Access page.

Eclipse Integrated Development Environment

The HostBridge Eclipse Integrated Development Environment (IDE) provides the tooling and functionality developers need to easily and rapidly author, test, and deploy HB.js scripts/Web services. The IDE includes HB Transaction Explorer, a graphical display generated by HostBridge XML that replicates CICS screens with precise fidelity. Developers use this tool to navigate live terminal-oriented CICS application micro flows as a means of developing highly reliable integration scripts/services.

zIIP-Enablement for HostBridge JavaScript

HostBridge is authorized to run its software products and scripts/Web services on the IBM z Integrated Information Processor (zIIP). By shifting HB.js processes to the zIIP, customers can reduce processing costs, lower mainframe TCO, and often improve performance. To learn more about HostBridge zIIP-enablement, visit our HostBridge for zIIP page.

Orchestrating CICS Terminal-Oriented Transactions as a Service

HB.js offers a unique means for developers to improve performance by incorporating the most complex CICS transaction micro flows into single, reusable Web services. Carrying out a complete business process with a terminal-oriented CICS transaction micro flow can involve interaction with dozens or even hundreds of screens. Trying to integrate these micro flows using sub-standard integration technologies has had serious performance impacts. Products that run in the middle tier require a full request-response cycle with the mainframe for each transaction, consuming processes unnecessarily and causing latency.

HB.js handles transaction micro flows far more efficiently and economically. When a request is submitted to HostBridge – whether from a user or a mobile, Web, cloud, or other distributed app – the HB.js script/service executes the entire transaction sequence on the mainframe, orchestrating and aggregating all relevant data and returning a single response, typically with sub-second response times.

Orchestrating z Systems Resources as Services

HB.js also provides a unique and powerful means to incorporate a wide range of z Systems resources into single, streamlined, reusable Web services. With HB.js, developers can to orchestrate and aggregate CICS terminal-oriented transactions, CICS programs, and z Systems data together, incorporating them all into composite scripts/Web services.

Dynamic Applications Using Objects and Services

Many customers now use HB.js to write new dynamic applications that leverage JavaScript’s object-oriented capabilities within a Web services application architecture to reinvent complex legacy applications as modern composite apps for today’s workforce.

A number of our customers in the insurance industry rely on a highly complex legacy terminal-oriented CICS applications that lack micro flows. Instead, each screen is discrete, and insurance reps must move from screen to screen, or go back and complete prerequisite screens, based on thousands of screen codes. Training on the application took months, and when the company tried to integrate with a new enterprise-wide front end, there was only one solution.

Using HB.js, developers have recreated each screen as a discrete JS object that calls all prerequisites and potential following screens without user intervention. Then, at a higher Web services layer, a business service calls required objects and assembles them into a complete business process that is fully integrated into the front-end application. At any time, developers can modify services or write new ones, calling the same objects, and thus update or recreate business processes – modernizing and gaining maximum value from CICS and z/OS without touching any mainframe code.

JavaScript & JSON for Web Services Development

One of our guiding principles at HostBridge is that z Systems customers will gain the greatest return on investment when they expose z Systems apps and data using the same high-performance, industry-standard technologies used by today’s leaders in mobile, Web, and cloud computing.

Leveraging JavaScript and JSON, industry-standard languages that are now active in every computing system from client devices to app servers to HostBridge on the mainframe, our server-side HB.js exemplifies our guiding principle, providing customers with the greatest possible power, flexibility, and economy in systems interoperability.

In addition, JavaScript and JSON are among the most widely known languages in the world today. With HB.js, Web and distributing application developers already on staff can immediately begin developing JavaScript- and JSON-based Web services for CICS and z/OS. Compared with other programming choices, HB.js ensures easier development, faster deployment, the highest fidelity to CICS applications, and the most reliable integration for CICS and other z Systems assets.

Product Evolution and Naming: Process Automation to HB.js

The first HostBridge JavaScript technology was part of a product released in 2004 called HostBridge Extended (HBX). Soon after its introduction, customers began using HBX to orchestrate and automate CICS transaction micro flows, and the JavaScript component became known as Process Automation. Over time, as we and our customers used the product for a very broad range of orchestration, integration, and dynamic application development, it became clear that the name HostBridge JavaScript Engine (HB.js) best communicated product methods and principles to the IT professionals with whom we work.

HB.js is JavaScript and JSON for z Systems and CICS.


[1] HB.js was formerly known as the HostBridge Process Automation Engine.

[2] HB.js v6 is built on this latest ECMAScript/JavaScript code base. HostBridge Technology continues to support v4 and v5, built on earlier code bases.