SAP S/4HANA Extensibility Options For Clean Core Journey

Experts, before getting into the topic, let’s understand the motivation and purpose of the new modern extensibility options defined by the SAP for SAP S/4HANA Public, On-premise, and PCE editions.

Motivation

A cloud-first approach is becoming the new normal powered by software-as-a-service (SaaS) applications with AI/ML, digital assistants, automating routine tasks, better user experience, flexible and agile operating model. SAP is bringing innovation into the core ERP business processes with frequent product release updates. SAP is also providing freedom to go beyond standard ABAP language with a BTP side-by-side extensibility approach using BTP ABAP Cloud, Java, node.js, BYOL, etc. to build full-stack applications which will run in parallel with ERP which is challenging with the classic extension options. The extensibility option is a key capability of an ERP application that enables customers to customize their business processes with a competitive advantage in the industry and allows partners to enrich ERP with tailor-made solutions. The importance of extensibility has been confirmed by the legacy ERP flagship product SAP ECC and will remain valid for the current and future cloud ERP transformation.

SAP S/4HANA is a front-runner product providing intelligent ERP in the cloud and on-premise. The goal is to shift from the classic ABAP extensibility model to an SAP S/4HANA modern extensibility model that allows customers to consume SAP innovations, building future-proof extensions that are ready for the cloud ERP. For all, it is important to understand and know how SAP is shifting away from a monolithic architecture (SAP ECC era) to a microservices architecture that is modular, flexible, continuous deployment, and agile (SAP S/4HANA era with BTP).

There is chaos in the developer’s community, how do we connect the dots for customers that are on traditional ABAP so they can take advantage of modern innovations? What is a new extension model? What is Embedded Steampunk, BTP ABAP environment? SAP CAP (Java, node.js)?  What is Side-by-side BTP Extension? How it is different from standard ABAP?  Where can we use SAP Build Apps with ERP?  And more questions.

Contents

1. Current customer situation
2. Challenges with the classic extensibility model
3. What are the extensions?
4. Why does SAP S/4HANA need extensibility?
5. What and why about the clean core concept?
6. What is the new extensibility model?
7. SAP S/4HANA Extensibility Options
   1. Key User (In-app) Extensibility
   2. On-stack Developer Extensibility
   3. Side-by-side Extensibility
   4. Classic Extensibility
8. 3-tier extensibility model for SAP S/4HANA On-premise and PCE editions
9. How to handle Classic Custom Code Migration?
   • ABAP Cloud Use Cases – Overview and Recommendations
   • Classic RICEFW Vs Modern Extensibility With BTP
10. Decision Matrix for Extensibility Options

Current customer situation

Our business is doing fine with the classic ABAP extensions. We have spent a huge amount of effort in building the custom processes as per the business demands. Our system has become complex over time due to customizations and enhancements. Classic extensibility is extremely powerful and flexible to meet every single requirement of the business and keep them happy regardless of the system that has become over time inefficacious and substandard performance. We are facing challenges in terms of high maintenance IT cost and lack of innovation. Our goal is to become Intelligent Enterprise with digital ERP transformation. Reduce the costs, modernize to keep up with the competition, and bring value from our operational data.

Challenges with the classic extensibility model

1. High TCO for system maintenance and software upgrades.
   • Extensive planning and testing. Making sure the upgrade does not break the system.
   • Software changes lead to high adoption efforts.
   • SAP Standard code and Customization are not clearly separated, there is no interface.
   • Classic extensibility adds complexity to the SAP Core and averts from adoption of agile practices and standardized business processes.
   • Redundant data and unused custom code living within the core ERP system.
   • Example: You have used an SAP object that is not whitelisted by SAP in your extension. After an upgrade, the used SAP object has been changed or deleted. Now you will have to adjust the extension thus upgrade is delayed and the speed of innovation is decreased.
2. The slow rate of innovation as the system was modified via standard and custom codes.
3. Limitations and struggle to reach the fast-changing business needs to compete and lead.

What are the extensions?

• Software engineering principle for enhancements without impairing existing system functions.
• It can be the addition of new functionality or modification of existing functionality.
• Measure the ability to extend and the effort required to implement an extension.

Why does SAP S/4HANA ERP need extensibility?

• Extend business process for optimization, innovation, or automation
• Extend the UX of existing processes and provide controlled access for external user groups
• Extend data insights & analytics  by combining data in one central place
• Extend the ecosystem with side-by-side Software as a Service (SaaS) apps

ERP Extensibility

What and why about the clean core concept?

Let’s understand the meaning behind the Clean + Core.

Clean… up-to-date, transparent, unmodified, consistent, efficient, and cloud compliant.
Core… the main aspects of an ERP system are extensibility, processes, data, and integration.

The clean core is an extension methodology concept with the basic goal i.e.  Extensions should not break an upgrade and upgrades should not break an extension. Follow the rules:

1. Fit-to-Standard: Leverage SAP standard processes when possible.
2. Apply a zero-modification policy from the project’s first day.
3. Leverage the full potential of new extension options (In-App, Developer, or Side-by-Side ) which fit your needs best.​Use whitelisted and released APIs.​
4. Eliminate enhancements that are redundant to standard code and functionality, as well as “clones” of standard code.​
5. Think and act like moving SAP S/4HANA on-Premise to SAP S/4HANA Cloud by
   using capabilities of SAP BTP Extension & Integration Suites for application development and integration.

Some principles when building extensions to keep the core clean.

How to plan and adopt a clean core strategy for an SAP S/4HANA ERP transformation project?

• Greenfield project: Start with the stay clean strategy to bring system the system closer to standard processes, and keep the system up-to-date, including modern extensibility and integration options as well as data governance.
• Brownfield project: Start with the get and keep clean strategy to bring system the system closer to standard processes, including the transformation from traditional custom code to modern extensibility, integration capabilities, and duplicate data cleansing.

Understood! Tell me the benefits of it:

1. Reduce TCO (Time, Effort & Cost)
   • Faster deployment and Ready for a smooth upgrade.
   • Reduce test efforts for business users and Adoption efforts for developers.​
   • IT service providers can offer upgrade projects at a fixed price.
   • No costly maintenance for unused artifacts and data.​
2. Innovation at Market Speed.
   • Captivate innovation delivered by SAP.
   • React fast to changing business requirements.
3. Data to value.
   • Consistent data allows for reliable forecasting and predictions for confident decisions.
4. Become cloud-ready and Competitive at any point in time.
   • Moving SAP S/4HANA on-Premise to SAP S/4HANA Cloud.

Learn more, Get your organization in shape: Keep a Clean Core with SAP Business Technology Platform.

Now you have clarity clean core concept and benefits. Let’s get into the main topic.

What is the new extensibility model?

This new SAP S/4HANA Cloud extensibility model, first introduced in SAP S/4HANA Cloud public edition, is now available and recommended in all SAP S/4HANA editions, to achieve the following:

• Smoother upgrades.
• Little to no testing efforts.
• Simplified adoption and LOBs drive innovation timelines.
• Standardized and optimized business processes.
• Pave the way to the cloud.

Let’s understand the various new options/tools available to create stable extensions in the SAP S/4HANA ERP system by following the clean core principle, even when the classic extensibility model is still available for the on-premise, private editions and recommendations are NOT to adopt it.

SAP S/4HANA Extensibility Model Options

SAP S/4HANA New Extensibility Model Options

The new extensibility model in SAP S/4HANA can be divided into three parts:

1. Key User Extensibility in the SAP S/4HANA Core
2. Developer Extensibility in the SAP S/4HANA Stack
3. Side-By-Side Extensibility on the SAP Business Technology Platform

1. Key User (In-app) Extensibility

SAP Fiori extensibility apps(tools) help you to customize user interfaces, processes, email templates, or forms using a low-code/no-code(LCNC) paradigm. It empowers business experts or citizen developers (typically a user from the business department) to add extensions to SAP solutions without the need to dive deeply into the implementation details. They typically have deep knowledge of business processes and configuration with no or only limited coding or debugging skills. Some development skills are recommended for developing custom business objects and adding business logic using the cloud ABAP web editor.

The main argument for using key user extensibility is that simple extensions can be realized quicker than with developer extensibility because of the communication overhead between the business expert (responsible for the specification of the extension, and later for testing and approval) and the developer (responsible for development and developer test) is avoided.

Find other Key User Extensibility apps:

1. Go to the SAP Fiori apps reference library
2. Search for the title of the app you want to configure
3. Choose your product (S/HANA Cloud or S/4HANA)
4. Change to the tab Implementation

Key user Extensibility Pattern Architecture

Key User Extensibility Tools

2. On-stack Developer Extensibility

This option bridges the gap between the key user and side-by-side extensibility options. On-stack developer extensibility enables you to develop custom ABAP code, and partner extension developments requiring coupling with SAP S/4HANA data, transactions, or apps using a restricted ABAP version. The requirements of the extension project go beyond the scope of key user extensions.

• Eclipse-based IDE (ABAP Development Tools) with a debugger, troubleshooting, and testing tool support
• A cloud-optimized subset of ABAP language i.e. ABAP Cloud syntax.
• ABAP RESTful Application Programming model (RAP) to build upgrade-safe extensions inside your core ERP system.
• Only use released APIs and the stricter syntax check of ABAP Cloud. (Note that to fully utilize this you need to be on a recent version of S/4HANA >= 2022 though it’s still possible to follow this system with older releases.)

In contrast to side-by-side extensions, on-stack developer, and key user extensions are developed and run on the same software stack as the underlying SAP S/4HANA system. This allows extensions to direct access SAP S/4HANA logic and data via SAP extension points(BAdis), local public CDS views, SAP-released APIs, or SQL queries.

Developer Extensibility Pattern Architecture

ABAP for Cloud Development

Developer Adaptation Project

Adaptation projects are currently only supported on the S/4 HANA on-premise ABAP system or the Cloud Foundry environment, for the S/4HANA cloud it may be supported in the future, refer to the product roadmap for more details. SAP S/4HANA cloud extensibility explorer.

3. Side-by-side Extensibility

Extensions running on the separated (side-by-side) SAP Business Technology Platform (SAP BTP) for all other loosely-coupled extension scenarios integrating with the extended SAP S/4HANA system. This model is the preferred option for developing loosely coupled but seamlessly integrated extensions to SAP S/4HANA data, transactions, or apps.

Develop custom code side-by-side extension and SaaS solutions using ABAP RESTful Application Programming Model (RAP) and SAP Cloud Application Programming Model using Java, or Node.js. Use no-code/low-code applications like SAP Build Apps, Process Automation, and Build Workzone to build custom applications, process automation, and workflow management. One main difference compared to the on-stack extensibility model is that accessing business objects of SAP S/4HANA Cloud is only possible using remote APIs which are published in the SAP API Hub.

Side-by-side Extensibility Pattern Architecture

3.1 PRO-CODE

ABAP RESTful Application Programming Model (RAP)

New ABAP programming model for efficiently building cloud-ready enterprise apps and upgrade-stable extensions on SAP BTP ABAP environment, SAP S/4HANA Cloud, SAP S/4HANA Cloud ABAP environment, and SAP S/4HANA 1909 and higher.

• RAP is a powerful framework consisting of a set of concepts, tools, and languages.
• A strategic long-term solution for the ABAP developments.
• Help developers to build innovative, cloud-ready, enterprise applications of different domains, such as transactional and analytical applications.
• RAP offers a standardized development flow based on Core Data Services (CDS), the ABAP language, and business services in the modern, Eclipse-based ABAP Development Tools (ADT).
• RAP is available on
  • SAP BTP ABAP Environment (Steampunk), provides the ABAP platform as a service (PaaS) on SAP BTP. ABAP-minded customers and partners can reuse their ABAP skillset to build new cloud solutions, or to transform already existing on-premise ABAP assets to the cloud.
  • SAP S/4HANA ABAP Environment (Embedded Steampunk)

High-level RAP Programming Model

SAP Cloud Application Programming Model(CAP)

An open and opinionated framework of languages, libraries, and tools for building enterprise-grade services and applications. The CAP framework features a mix of broadly adopted open-source and SAP technologies

• CDS is the backbone of the SAP Cloud Application Programming Model (CAP) to build data models, defining the UI layer with those definitions (annotations)  and service definitions on a conceptual level.
• CAP-based projects benefit from a primary focus on the domain rather than delving into overly technical disciplines.
• SAP programming model is compatible with any development environment, but recommend using the SAP Business Application Studio.

High-level CAP Programming Model

SAP CAP Vs RAP model, which one to choose? The choice of the programming language for your extension – ABAP, Java, or JavaScript is decisive.

3.2 LOW-CODE

SAP Build Apps

Evolution of SAP AppGyver is a professional application development solution designed for anyone to quickly create apps without code regardless of role or skill level.

• Build Full-Stack Enterprise-Apps in Minutes – Absolutely Zero Coding Required
• Drag-and-drop the user interface and Create any logic without code.
• With SAP Build Apps everyone can become a full-stack cloud developer.
• Easily add your own data integrations or get started with some of ours.
• Users can design both mobile and web applications with a pixel-perfect design using the drag-and-drop functionality and a rich component library.

Note: SAP Build Apps is still evolving and due to limitations on the availability of different hyper scalers, other low code and pro code solutions become equally important.

SAP Build Process Automation

• Users can create forms, manage decision logic, and build, adapt, and organize process flows with drag-and-drop simplicity.
• Automate repetitive manual tasks – such as copy-and-paste operations, data extraction, data entry, and data creation – using no-code and low-code capabilities or the built-in automation recorder.
• Built-in AI capabilities enable intelligent document processing –like extracting data from structured or unstructured documents to transfer it to your enterprise systems for processing – without needing data scientist support.
• Simplifies process and task automation so business users can unleash their process expertise without writing code.
• Adapt, improve, and innovate business processes with no-code workflow management and robotic process automation capabilities.

SAP Build Work Zone

• Users can create beautiful, custom business sites for themselves, colleagues, suppliers, customers, partners, etc., without writing any code.
• Business sites created with SAP Build Work Zone provide central access to relevant applications, processes, and information.
• Maximize productivity by enabling guided experiences and knowledge sharing.

4. Classic Extensibility (Not available in SAP S/4HANA public edition)

This is the traditional way of the SAP ECC or S/4HANA on-prem enhancement for RICEFW ABAP custom object development like user-exits, customer-exits, classic BAdis, implicit/explicit enhancements, BTE, module-pool, etc using transaction code SE38, SE80, SE11 (SAP GUI, Eclipse ADT).

Basically using non-released objects from S/4HANA and an ABAP standard version (non-restricted). No restriction on the extension, it even allows you to modify the standard SAP code itself. Hence, upgrade effort increases and agility/innovation speed decreases.

Classic Extensibility Pattern Architecture

In S/4HANA On-Premise –The classical extensibility option is available but not recommended.

Available extensibility options for SAP S/4HANA editions

Key user, developer, and side-by-side extensibility are available for public and on-premise editions while the classic extensibility model is available only for an on-premise edition.

3-tier extensibility model for SAP S/4HANA On-premise and PCE editions

Refer official guide Chapter 5: EXTENDING A NEW SAP S/4HANA CLOUD PRIVATE EDITION OR SAP S/4HANA ON-PREMISE SYSTEM

3-tier extensibility model

How to handle Classic Custom Code migration?

1. Analyze the classic ABAP custom code with the Custom Code Migration App to estimate the impact. Custom Code Analysis for SAP S/4HANA with SAP Fiori App Custom Code Migration
2. Detect and Retire unused classic ABAP custom code. In the analysis, it is found that roughly 60% (sometimes even more) of the code is not used productively in a typical ERP system. Removing obsolete code significantly reduces the effort for custom code adaptation. At the same time, this is certainly a first step toward a clean digital core.

Learn more: ABAP Testing and Analysis

ABAP Cloud Use Cases – Overview and Recommendations

Refer official guide: ABAP Cloud – Technical Use Cases and Recommended Technologies

Classic RICEFW Vs Modern Extensibility With BTP

Decision Matrix for Extensibility Options

Refer official guide Chapter 3: WHEN TO USE WHICH CLOUD EXTENSIBILITY OPTION

*X – Not applicable for S/4HANA Public Cloud

The clean core is a journey to be agile, reliable, and more efficient. You can not just switch it on overnight. 😉

Questions?, Please use the blog comment feature or reach out to me on Linkedin.

Summary

• SAP S/4HANA provides a new extensibility model that clearly separates standard and custom developments.
• The classic extensibility option is not available for SAP S/4HANA public edition.
• A clean core strategy is important for customers to consider while extending an ERP application and be ready to consume product updates and innovations.
• Key-user extension is a great tool for business users without the need for IT support.
• Side-by-Side is an extensibility model that provides freedom to choose ABAP, Java, Node.js, etc., and build a full-stack application that will run in parallel with core ERP processes.
• An embedded ABAP environment offers values for both greenfield and brownfield projects.
• Retire unused code, Custom code migration and developments with modern cloud ABAP is a go-forward strategy to become cloud competent, modularized, and agile for business needs.

References:

1. SAP Business Technology Platform ABAP Environment – Solution Overview
2. Extend SAP S/4HANA in the cloud and on premise with ABAP based extensions
3. Developing on ABAP Platform – Extensibility
4. SAP Extensibility Explorer for SAP S/4HANA Cloud
5. Custom Extensions in SAP S/4HANA Implementations – A Practical Guide for Senior IT Leadership

Credits: This blog has been put together by combining the incredible efforts, suggestions, and feedback from the ABAP platform PM team (Olga Dolinskaja), CoE expert (Subit Benny), and Solution advisory expert (Ruhi Naaz Quadari) when deciding on the extensibility of S/4HANA using the Clean Core concepts.