Tier 1, Tier 2, and Tier 3 Extensibility Guidelines for Enterprise SAP

The 3-tier extensibility model is the foundational engineering strategy for achieving a Clean Core in enterprise SAP landscapes.

Tier 1: Cloud-Ready Core (ABAP Cloud)

• Language Version: 5 (ABAP Cloud)
• APIs: Strictly Released Public APIs (Contract C1)
• Persistence: Released CDS Views & RAP Business Objects
• Target Systems: SAP S/4HANA Public Cloud, Private Cloud, On-Premise (Developer Extensibility), and SAP BTP ABAP Environment.

Tier 2: Cloud API Enablement (The Quarantine Wrapper)

• Purpose: Bridge the gap when standard SAP has not yet released a C1 API for required functionality.
• Language Version: Classic ABAP (Language Version 1), but encapsulated behind a clean interface.
• Contract: Custom C1 Release Contract applied to the wrapper interface.
• Lifecycle: Temporary bridge. When SAP releases an official API in a future feature pack, you refactor only the Tier 2 wrapper—Tier 1 applications remain 100% untouched.

Tier 3: Classic Extensibility (Legacy Debt)

• Purpose: Maintain existing custom code without immediate rewrite.
• Scope: Quarantined away from modern applications.
• Target: Gradual refactoring or decommissioning during upgrade phases.

Suite & Blueprints: https://andreaperrelli.gumroad.com/l/sap-enterprise-architecture-suite