SAP's Clean Core strategy mandates the use of stable, released, and decoupled interfaces to ensure the system remains upgrade-safe and maintainable. OData and SOAP are the primary types of modern, synchronous APIs that SAP officially releases and recommends for building such integrations. These APIs are documented and discoverable on the SAP Business Accelerator Hub. They are designed to be upgrade-stable and are based on open standards (REST for OData, XML for SOAP), aligning perfectly with the principles of a clean, modern architecture.

B. IDoc: IDoc is a classic asynchronous integration technology. While still supported, SAP's modern integration strategy for Clean Core prioritizes modern, released APIs over these legacy methods for new developments.

D. RFC: Remote Function Call (RFC) is a classic, tightly coupled, and proprietary SAP protocol. Its use is explicitly discouraged in a Clean Core approach in favor of loosely coupled, standardized APIs.

1. SAP Official Documentation - Extensibility Guide for SAP S/4HANA Cloud: The guide outlines the extensibility patterns for maintaining a Clean Core. It emphasizes the use of released SAP APIs for side-by-side extensions. The guide states

"SAP S/4HANA Cloud offers a wide range of local and remote APIs that are based on standard protocols

such as OData and SOAP."

Source: SAP Help Portal

Extensibility Guide for SAP S/4HANA Cloud

Section: "Released SAP APIs". (A specific URL is dynamic

but this can be found by searching the title on help.sap.com).

2. SAP Whitepaper - Clean Core for SAP S/4HANA: This whitepaper details the principles of Clean Core

highlighting the importance of using public

stable APIs for integrations. It contrasts modern APIs (like OData and SOAP) with classic technologies.

Source: SAP Community Whitepaper

"An Introduction to Clean Core for SAP S/4HANA

" Page 5

Section: "Pillar 2: Integration." It advocates for using APIs from the SAP Business Accelerator Hub

which primarily features OData and SOAP services.

3. SAP Business Accelerator Hub: This is the central catalog for all SAP APIs. A review of the available APIs for SAP S/4HANA Cloud and On-Premise shows that the vast majority of recommended and released interfaces are OData and SOAP services

confirming their status as the preferred choice for Clean Core integrations.

Source: SAP Business Accelerator Hub

https://api.sap.com/. Filter by Product "SAP S/4HANA" to view the catalog of recommended APIs.