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Turn your mainframe into an API powerhouse


Mobile, web, and cloud technologies are enabling new kinds of business models in which innovative services can be created in a matter of hours from a palette of easy-to-consume application programming interfaces (APIs). Discover how to enable your enterprise to unlock its valuable systems-of-record assets and capitalize on this new ecosystem by building RESTful APIs that can access business-critical data.


A study by Boston Technology Group suggests that by 2018, some 68% of all mobile apps will be powered by APIs. APIs can help quickly address new market opportunities, which empower developers to use core business services to continuously build, refine, and deploy apps at top speed. Nearly 70% of all enterprise transactions touch a mainframe like IBM z System. These environments deliver business-critical applications and data to the enterprise and are a prolific contributor of needed services. In an API-driven world, the challenge for organizations is to monetize the value of their corporate data and enrich the user experience with third-party APIs.

This developer code pattern shows you how to enable z System and other platforms as API powerhouses. It demonstrates how to build RESTful APIs in order to offer more personalized, concierge-style services based on mainframe data. Using IBM z/OS Connect, Enterprise Edition, you will make your mainframe fully conversant with REST APIs and put your environment at the center of the API economy.



  1. The user logs into the z/OS Connect, Enterprise Edition (EE) API Editor to create an API project and a basic API that uses RESTful principles. The API will connect through a service to the COBOL application in CICS, IMS, or other application.
  2. The user associates the API to a service or z/OS asset using a service archive file. In z/OS Connect EE, a service archive file, or .sar file, represents the underlying z/OS asset. z/OS Connect EE provides tooling to generate .sar files for compatible subsystems (for example, CICS, IMS, DB2, and MQ).
  3. The user maps the API parameters to fields in the associated service and removes any irrelevant values from the response so that the API returns only relevant fields.
  4. The user packages and deploys the API from the API Editor to the z/OS Connect EE server. When the API is deployed successfully, it can be tested using the built-in Swagger UI.


Find the detailed steps for this pattern in the README. This code pattern uses two separate scenarios to show you how to use z/OS Connect EE to create, deploy, and test RESTful APIs that expose z/OS subsystems:

  • Scenario One: Expose a CICS COBOL program as a RESTful API
  • Scenario Two: Expose an IMS application as a RESTful API

The steps are the same for each scenario:

  1. Create the API Project.
  2. Create the API.
  3. Associate a service with the API.
  4. Map the request.
  5. Map the response.
  6. Deploy the API.
  7. Test the API.
Animesh Singh