SAP Clean Core

Comparing the Clean Core approach with the traditional approach in SAP development reveals a fundamental shift in strategy, particularly driven by the move to cloud-based ERP systems like SAP S/4HANA. While the traditional approach focused on deeply embedding customizations within the core system, Clean Core advocates for keeping the core as standard as possible and externalizing custom logic. Here’s a comparison of these two approaches:

1. Customization and Extensibility
   ●​ Clean Core: Employs a differentiated extension concept using various scenarios:
   ○​ In-App Extensibility (Key User Extensibility): Allows power users to create custom fields, business objects, analytical queries, or UI adaptations directly in Fiori using low-code/no-code principles.
   ○​ On-Stack Extensibility with ABAP Cloud: For more complex extensions within the SAP stack using the ABAP RESTful Application Programming Model (RAP) and released APIs in a dedicated, modification-free, cloud-compliant environment. ABAP Cloud enforces clean core by design.
   ○​ Side-by-Side Extensibility on SAP Business Technology Platform (BTP): Offers the greatest flexibility for complex, cross-module, or mobile applications developed and operated independently of the core system. Technologies like SAP Build Apps, SAP Build Code, CAP, or SAP Integration Suite enable loosely coupled extensions that function independently of the core.
   ○​ The Clean Core Level Concept (Levels A, B, C, D) provides a more granular assessment of custom extensions, classifying them from cleanest (Level A, fully compliant with stable SAP interfaces) to not clean (Level D, severe violations like modifications or non-recommended objects).

   ●​ Traditional Approach: Relied on direct manipulation of core SAP objects, using classic ABAP, implicit enhancements, or modifying SAP standard screens. These customizations were often tightly coupled with the core system.

2. Technical Debt
   ●​ Clean Core: Minimizes technical debt by limiting custom code and heavy customizations, making the core system cleaner and more manageable. Legacy code is isolated or retired.

   ●​ Traditional Approach: Results in high technical debt due to unmanaged, deeply embedded, and scattered changes, as well as the usage of non-recommended SAP objects or technologies.

3. Flexibility and Agility
   ●​ Clean Core: Achieves higher agility and flexibility, enabling faster response to changing business needs and quicker rollout of new features and innovations (including AI, ML, automation). It ensures extensions are done with long-term stability, scalability, and innovation-readiness in mind.

   ●​ Traditional Approach: Heavy custom code limits flexibility, slows down upgrades, and makes it harder to leverage the latest SAP innovations. Development practices can become a lagging factor instead of a leading edge for innovation.

4. Development Practices and Mindset
   ●​ Clean Core: Requires a shift in mindset from traditional on-premise approaches to cloud-centric models. It empowers teams with knowledge of SAP’s recommended programming models like RAP and CAP, encouraging a cloud-centric approach. Developers use modern tools and strictly defined APIs.

   ●​ Traditional Approach: Developers were accustomed to greater freedom in modifying SAP objects directly. The traditional “WRICEF” (Workflows, Reports, Interfaces, Conversions, Enhancements, Forms) model was common.

5. Challenges and Disadvantages
   ●​ Clean Core: Requires acquiring new knowledge and skills (e.g., ABAP Cloud, BTP, API-based development). It demands a cultural shift and can face resistance from stakeholders accustomed to older methods. Some simple adjustments in a non-Clean Core system might become more complex in a Clean Core system. There can be initial time and cost overhead for setup and training.

   ●​ Traditional Approach: While offering immediate flexibility in making direct changes, it posed long-term problems. Challenges included managing an increasing volume of custom code, difficulty in tracking dependencies, and the eventual impact on upgrades and system performance.