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IBMi(AS/400) Reverse API Cobol Client Deployment

This guide provides step-by-step instructions for compiling and deploying an OpenLegacy-generated COBOL program with HTTP API support on IBM i using the HTTPAPI library.

Prerequisites

Make sure you have the following:

  • IBM i (iSeries/AS400) OS version 7.1 or newer
  • ILE COBOL compiler
  • HTTPAPI library installed and in your library list - Follow the link above. Download and follow the installation instructions HTTPAPI
  • OLREVAPI RPGLE service program (compiled)
  • OLAPICPY.CPY copybook file from OpenLegacy
  • The COBOL program source generated by OpenLegacy
  • The minimal permissions needed are *USE authority on each library and required source, *ADD and *OBJMGT authority on the target library for creating or updating objects, and *USE authority on all referenced modules and service programs.

Step 1: Configure API Parameters

Edit the OLAPICPY.CPY copybook to specify your server URL and any required API key.

Set the API Endpoint

Locate or add URL:

05 OLREVAPI-URL PIC X(512) VALUE

Multi-line URL: To break a long URL into multiple lines, continue with a hyphen in column 7 of each following line:

            05 OLREVAPI-URL PIC X(512) VALUE 'https://'
       -      'your-api-url.amazonaws.com'
       -      '/apps/your-api-uri'.

Use Environment Variables

To set the URL at runtime via an environment variable:

            05 OLREVAPI-URL PIC X(512) VALUE "ENVVAR:YOUR_ENV".

Set the API Key

If your API requires an x-api-key:

            05 OLREVAPI-API-KEY PIC X(32) VALUE 'your-api-key'.

Copy the updated OLAPICPY.CPY to your source physical file member (e.g., MYLIB/QCBLLESRC).

Step 2: Update the COBOL Program

Copy your COBOL source to the correct member in your source physical file.*

Step 3: Create the COBOL Module

Add the Library where you copied the copybook from Step 1

ADDLIBLE MYLIB

Run the following command to compile your COBOL module:

CRTCBLMOD MODULE(MYLIB/COBOL_CLIENT)
SRCFILE(MYLIB/QCBLLESRC) SRCMBR(COBOL_CLIENT)
OUTPUT(*PRINT) DBGVIEW(*ALL)
PGMINFO(*PCML *MODULE)

Replace MYLIB and COBOL_CLIENT with your actual library and program names.

📘

Explanation: This command compiles your COBOL source member into an ILE module on IBM i. The module is an intermediate compiled object, which you will later bind with other required modules and service programs. Setting DBGVIEW(*ALL) enables comprehensive debugging information for troubleshooting. PGMINFO(*PCML *MODULE) includes metadata useful for interoperability and debugging.

Step 4: Add the HTTPAPI Library

Before linking, add HTTPAPI to your library list:

ADDLIBLE LIBHTTP
📘

Explanation: The IBM i system uses a library list to locate required objects during compilation and binding. Adding the HTTPAPI library makes its service programs (such as HTTPAPIR4) available for linking, ensuring your program can call HTTP functions at runtime.

Step 5: Link and Create the Program

Finish by creating the program and binding the necessary modules and service programs:

CRTPGM PGM(MYLIB/COBOL_CLIENT)
MODULE(MYLIB/COBOL_CLIENT SERVICE_LIB/OLREVAPI)
BNDSRVPGM((HTTPAPIR4 *IMMED))

Replace MYLIB and COBOL_CLIENT with your actual library and program names. Replace SERVICE_LIB as appropriate for your system.

📘

Explanation: This step links your COBOL module (MYLIB/COBOL_CLIENT) and the OLREVAPI service program (SERVICE_LIB/OLREVAPI) into an executable ILE program. The BNDSRVPGM((HTTPAPIR4 *IMMED)) directive immediately binds the HTTPAPI runtime service, enabling REST/HTTP calls from your COBOL logic. Confirm all libraries and object names are correct before running this command.



Updated about 12 hours ago