Exposing CICS and IMS programs as APIs

The request's journey

z/OS Connect

IBM z/OS Connect is the most common way to do this. You describe the API in an OpenAPI document, map each request and response field to the copybook, and z/OS Connect calls the program through CICS, IMS, MQ or DB2. The COBOL program still receives a COMMAREA or a channel and containers exactly as before.

• One API, many programs. GET /accounts/{id} might call ACCTINQ, while POST /payments calls PAYPOST.
• Path and query values such as {id} are mapped into input fields.
• Program results become HTTP status codes — for example, a not-found flag in the output becomes 404.

Other routes

• CICS web support lets a CICS program handle HTTP requests itself, with the CICS JSON assistant generating the conversion. More control, more code.
• DB2 REST services expose a single SQL statement or stored procedure as a REST endpoint, useful for simple reads.
• MQ is common when the caller should not wait: the request is put on a queue and processed asynchronously.

$ curl -H "Authorization: Bearer eyJhbGciOi..." \
    https://api.examplebank.com/accounts/00412789
 
HTTP/1.1 200 OK
{ "accountId": "00412789", "name": "Asha Rao", "balance": 1520.75 }