Side-by-Side Extensibility Patterns for SAP S/4HANA

Keep this: job aid

Side-by-side extension design checklist

• Try key user tools first; go on-stack with ABAP Cloud when logic must run inside the SAP transaction.
• Go side-by-side for external users, new apps, cross-system processes and independent lifecycles.
• Name the pattern for each part: UI, process, event-driven, data or integration.
• List every API and event; confirm each is released for your edition and activated in CMD, CMQ and CMP.
• Keep downloaded API specifications and event references in source control.
• Decide the identity toward SAP S/4HANA: narrow technical user or principal propagation.
• One destination per subaccount, paired with its SAP S/4HANA stage; private systems through the Cloud Connector.
• Least privilege: narrow communication-user roles and Cloud Connector path allowlists, in test too.
• Tests per pattern: mocked service tests, contract tests, integration in test, few end-to-end flows.
• Event extensions: test duplicates, out-of-order delivery and subscriber outages.