Tier-2 Extensions
Develop future-proof in the 3-tier extensibility model. Learn how to cleanly encapsulate legacy code and make your ERP extensions cloud-ready.
What is Tier-2 ABAP Cloud extensibility and how does it work?
In the SAP ABAP Cloud extensibility model, Tier-2 (Cloud API Enablement) acts as the bridge for legacy custom code that cannot run directly in Tier-1 (Developer Extensibility) because it uses unreleased SAP APIs or direct table access. Tier-2 encapsulates these legacy dependencies using wrapper classes and custom CDS views, releasing them with a stable, local API. This allows Tier-1 cloud-native RAP applications to consume legacy business logic safely without breaking the Clean Core.
The ABAP Cloud 3-Tier Extensibility Model
To ensure the upgradeability of S/4HANA systems, SAP introduced the 3-tier extensibility model. This divides all ABAP developments into three separate layers:
Tier 1: Cloud-Native ABAP
The pure cloud standard. Uses exclusively released language elements (ABAP Cloud) and SAP APIs. This code is absolutely upgrade-safe and runs directly in public cloud environments.
Tier 2: Cloud Readiness Wrapper
The encapsulation layer. If required SAP features are missing in Tier-1, a custom API is built in Tier-2 to encapsulate the legacy access and provide a clean Tier-1 interface.
Tier 3: Legacy ABAP
The classical development layer. Allows modifications and the usage of obsolete tables (e.g., VBAK). Tier-3 is the typical upgrade blocker and should be gradually decommissioned.
Sensible Usage of Tier-2 Extensions
The goal of Clean-Core.io is to migrate your legacy ABAP code as much as possible to Tier-1 or BTP CAP (Side-by-Side). Where this is not immediately possible due to missing standard APIs, our platform automatically generates the appropriate Tier-2 wrapper.
Through this automated encapsulation, your main application code remains clean and future-proof. Once SAP releases an official API for the encapsulated function at a later stage, the Tier-2 wrapper can be easily replaced by the standard API without breaking business logic.
Benefits at a Glance
- Structured legacy decommissioning
- Future-proof API encapsulation
- Minimizes Tier-3 dependencies
- Upgrade-ready system architecture
Frequently Asked Questions (FAQ)
What distinguishes Tier-1 from Tier-2 ABAP Cloud code?
Tier-1 (cloud-native ABAP) uses exclusively released SAP APIs and CDS views. Tier-2 (Cloud Readiness) serves as a wrapper layer to cleanly encapsulate unreleased SAP objects and make them accessible to Tier-1 via released interfaces, keeping Tier-1 clean.
When are Tier-2 extensions mandatory?
Tier-2 is necessary when legacy system tables or customer-specific custom (Z) tables must be integrated without official SAP APIs. Instead of polluting Tier-1 code with these legacy structures, an encapsulation layer is inserted in between.