Clean Core Architecture Decision Matrix (S/4HANA & BTP)
This decision framework outlines how to architect extensions on modern SAP S/4HANA (Cloud & On-Premise) and SAP Business Technology Platform (BTP).
[Business Requirement]
│
▼
Is it simple UI branding, custom field, or basic validation?
├── YES ──► [Key User Extensibility] (Low-code/No-code, in-app)
└── NO
│
▼
Does the business logic require transactional coupling with Core ERP data?
├── NO ──► [Side-by-Side Extensibility on SAP BTP]
│ (Kyma / Cloud Foundry / CAP / Node / Java / AI Services)
│
└── YES ──► [On-Stack Developer Extensibility (ABAP Cloud)]
│
▼
Does a Released SAP API (C1 Contract) exist?
├── YES ──► Implement Tier 1 with RAP (RESTful Application Programming)
└── NO ──► Implement Tier 2 Custom Wrapper Interface
Clean Core Levels (SAP S/4HANA & BTP)
| Level | Classification | Contract / Language Version | Permitted Technologies |
|---|---|---|---|
| Level A | Clean Core | Language Version 5 (ABAP Cloud) | RAP, Released CDS Entities, Key User Tools, BTP Side-by-Side |
| Level B | Transition Core | Classic ABAP (Version 1) with Tier 2 | Encapsulated custom wrappers around non-released standard APIs |
| Level C | Legacy Debt | Classic ABAP (Version 1) | Unwrapped BAPIs, direct DB SELECTs, modifications |
| Level D | Hard Anti-Pattern | Any | Core modifications, direct DB INSERT/UPDATE/DELETE on SAP tables |
Reference: The Definitive Guide to ABAP Cloud & Clean Core Extensibility by Andrea Antonio Perrelli. Full suite & architecture diagrams: https://andreaperrelli.gumroad.com/l/sap-enterprise-architecture-suite
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