Support for calling REST services from Natural via an API with a defined interface

A capability should be provided via the Natural API Server to allow REST services to be called from Natural modules. Similar to EntireX and RPC, this should be possible via CALLNAT using a defined PDA. The interface object should be generated from the OpenAPI/Swagger description of the REST service, enabling the service to be called via CALLNAT. As a limitation that would be acceptable for us, the mapping of REST parameters and responses could be restricted to the structures available in Natural, for example three-dimensional arrays, analogous to the existing Software AG IDL Grammar (Software AG IDL Grammar).

System-side provision of a CALLNAT with a dedicated interface would simplify the application programs considerably. When using REQUEST DOCUMENT, the following effort is currently required, which could be avoided by using a defined PDA:

• Building the request structure using COMPRESS and format transformations

• Calling the REST API via REQUEST DOCUMENT

• Reading the response with PARSE XML/JSON in a loop and checking the relevance of each element in a DECIDE structure

• Mapping the relevant field contents from XML/JSON to the corresponding Natural variables

• Potential format transformations to Natural formats such as N, P, I, D, and L

• General error handling