There are a few reasons why you would recommend building SAP Side-by-Side Extensions to an S/4HANA system based on SAP BTP.
SAP BTP is a cloud-based platform, which means that extensions can be developed, deployed, and managed in the cloud. This makes it easy to scale and manage extensions, and it also makes it easier to collaborate with other developers.
SAP BTP provides a number of services that can be used to build extensions, such as SAP Cloud Platform Integration and SAP Cloud Platform Event Mesh. These services can help to make extensions more scalable, reliable, and secure.
SAP BTP supports a variety of programming languages, which means that developers can use the language they are most comfortable with. This can help to make the development process more efficient and productive.
In addition to these reasons, SAP BTP also allows extensions to maintain SAP user and security context and allow the use of S/4HANA eventing. This is important because it ensures that users are only able to access the data and functionality that they are authorized to access, and it also allows extensions to react to events that occur in S/4HANA.
Therefore, SAP BTP is a good choice for building SAP Side-by-Side Extensions to an S/4HANA system.
Extensions on SAP BTP can maintain SAP user and security context, which means that the extensions can use the same authentication and authorization mechanisms as the S/4HANA system and respect the user roles and permissions defined in the S/4HANA system.
Extensions on SAP BTP can use S/4HANA eventing, which means that the extensions can subscribe to business events that are triggered by the S/4HANA system and react to them accordingly. For example, an extension can listen to a sales order creation event and perform some additional logic or integration based on the event data.
Extensions on SAP BTP can leverage the SAP Cloud Platform Integration Suite and the SAP HANA Data Management Suite, which provide a comprehensive set of services and tools for different integration scenarios, such as process integration, data integration, analytics integration, user integration, and thing integration.
Extensions on SAP BTP can benefit from the cloud-native capabilities of SAP BTP, such as scalability, elasticity, availability, and security. Extensions on SAP BTP can also take advantage of the various programming languages, frameworks, and technologies supported by SAP BTP, such as Java, Node.js, Python, Go, PHP, CAP, or serverless functions.
Verified Reference: 6: https://help.sap.com/viewer/9d1db9835307451daa8c930fbd9ab264/2020.002/en-US/6f7b0c5a5e0d4f8a8b7c0e9c6b6a7f5e.html#loio6f7b0c5a5e0d4f8a8b7c0e9c6b6a7f5e__section_2
Topic 1, Case Study – Wanderlust
Introduction
Wanderlust GmbH, headquartered in Germany but with manufacturing facilities and sales globally, is a leading global manufacturer of conventional fuel driven cars. They are renowned for their best-in-class engineering, but not so much for aftermarket customer service. In recent years, Wanderlust has had limited success expanding into the market of electric vehicles. Following is Wanderlust’s geographical manufacturing and supply spread:

Wanderlust offers one compact electric Sedan (model ELAN) and one compact electric SUV (model ELUV), each with three variants – basic (LX), mid-range (VX) and high-end (ZX). Customers can also choose from a range of five metallic colors, two drive trains and two battery ranges.Overall, 50 different combinations are offered for all segments and variants put together.
Extracts from CEO Interviews – Business Environment
Constraints/Issues
o Stiff water consumption regulations and enormous penalties for violation – Lithium extraction is a heavy water intensive process and mine locations are in very arid areas like the Australian outback and Atacama Desert o Significant dependence on external suppliers of Lithium batteries due to limited number of manufacturing units, long lead times and high carbon footprint in all car manufacturing facilities except Brazil.
o Long delays in spare battery availability, leading to an avalanche of unresolved battery related customer complaints for vehicles under warranty o Limited charging infrastructure, long charging cycles (as compared to refilling fuel) and slow resolution of battery related complaints.
o Dwindling in store footfall due to pandemic (for feature-based vehicle selection prior to test drive) Wanderlust offers one compact electric Sedan (model ELAN) and one compact electric SUV (model ELUV), each with three variants – basic (LX), mid-range (VX) and high-end (ZX). Customers can also choose from a range of five metallic colors, two drive trains and two battery ranges.Overall, 50 different combinations are offered for all segments and variants put together.
Extracts from CEO Interviews – Business Environment
Constraints/Issues
o Stiff water consumption regulations and enormous penalties for violation – Lithium extraction is a heavy water intensive process and mine locations are in very arid areas like the Australian outback and Atacama Desert o Significant dependence on external suppliers of Lithium batteries due to limited number of manufacturing units, long lead times and high carbon footprint in all car manufacturing facilities except Brazil.
o Long delays in spare battery availability, leading to an avalanche of unresolved battery related customer complaints for vehicles under warranty o Limited charging infrastructure, long charging cycles (as compared to refilling fuel) and slow resolution of battery related complaints.
o Dwindling in store footfall due to pandemic (for feature-based vehicle selection prior to test drive) Extracts from CIO Interviews – IT Environment Extracts from CIO Interviews – IT Environment Strategic Priorities – IT o Ease of usage o Ease of Maintenance o Total Cost of Ownership Optimization o Time to Value Acceleration Transformation Status o Only at a conceptual stage – no planning done yet o Nascent architecture practice o Unclear on supported processes, required capabilities, applications, and transition path o Yet to identify, prioritize and sequence initiatives As-Is Architecture

Wanderlust has a separate organization and setup for their Automobile and Aftermarket businesses o Wanderlust is reluctant to consider cloud for Core applications due to data privacy concerns, but are open for Collaboration applications o Automobile business started off in Europe and grew through acquisitions in Asia and Americas o Automobile business runs on three continental SAP ECC instances with inherited, disparate processes, which need to move to S/4HANA o Automobile business is also looking to harmonize their processes across the continents, adopt a seamless, transparent global supply chain for batteries and consolidate the continental instances into a global single instance, data regulations permitting o Automotive business uses a highly complex custom developed dealer management solution on ECC, which needs to be replaced o Automotive business uses SAP APO, which is nearing end of lifecycle and needs to be replaced by IBP (DP & SNP) & S/4HANA (PP-DS) o Automotive business uses several bespoke non-SAP applications, which are considered irreplaceable, except for the Marketing and Sourcing applications, which are expensive to maintain, seldom used and henceneed to be replaced o Aftermarket business processes are largely uniform and handled through a single ECC instance which also should move to S/4HANA o Aftermarket business uses SAP SCM which is nearing end of lifecycle and needs to be replaced by S/4HANA AATP (gATP) and eSPP (SPP) Extracts from Interview with Enterprise Architect Enterprise Architecture Dimensions & Maturity o Wanderlust’s Key EA Dimensions, their overall purpose and current maturity level

Top three priorities given the current maturity level, are as follows
o Stakeholder Involvement is the topmost priority, to create a Stakeholder Map that’ll identify all key EA stakeholders within Wanderlust o Business-IT Alignment is also a top priority, to anchor every IT initiative to a Business Strategy Map, consisting of clearly defined strategic business objectives, tangible goals and measurable value drivers o Architecture Development is the next priority, beginning with development of business architectures, followed by application architectures and finally opportunities & solutions planning Enterprise Architecture Practice Structure (Current)

Enterprise Architecture Principles
o Wanderlust’s Enterprise Architecture Principles are a collection of crisp and precise one liners pertaining to business, application, information, integration, technology and security aspects of transformation o Some of the EA Principles in the repository are

These EA Principles serve as high level directional statements and long term guard rails to the above six aspects of transformation programs & projects o They should ideally correlate (many to many) with the Strategic Objectives, defined in the Business-IT alignment EA Dimension – this is yet to be done though

https://community.sap.com/t5/technology-blogs-by-sap/integration-solution-advisory-methodology-isa-m-define-integration/ba-p/13397214

Explanation
According to the SAP Enterprise Architect framework, which is based on the TOGAF ADM, the next steps are:
Reviewing Business, Application/Data, and Technology Architecture artifacts with stakeholders and signing off on first versions. This step involves validating and verifying the architecture designs with the relevant stakeholders, such as business owners, users, developers, and vendors. The goal is to ensure that the architecture designs meet the requirements and expectations of the project, and to obtain formal approval for the first versions of the artifacts.
Using Transition Architectures to build the Architecture Roadmap. This step involves defining and prioritizing the Transition Architectures, which are intermediate states between the Baseline Architecture (the current situation) and the Target Architecture (the desired future state). The Transition Architectures describe how to move from one state to another in a feasible and manageable way, taking into account the constraints and dependencies of the project. The Architecture Roadmap is a document that outlines the sequence and timing of the Transition Architectures, as well as the deliverables, resources, and risks associated with each one.
Creating first drafts of the required work packages and the Project/Rollout plan. This step involves identifying and defining the work packages, which are units of work that can be assigned to a project team or a vendor for implementation. The work packages specify the scope, objectives, dependencies, assumptions, and acceptance criteria of each unit of work. The Project/Rollout plan is a document that describes how to execute and monitor the work packages, as well as how to manage the change management, quality assurance, and governance aspects of the project.
The other options (B and C) are not correct for the next steps required after the architecture designs have been created, because they either skip or misrepresent some of the steps in the SAP Enterprise Architect framework.
For example:
Option B is not correct because it does not include reviewing and signing off on the first versions of the architecture artifacts with stakeholders, which is an important step to ensure alignment and agreement on the architecture designs. It also does not mention using Transition Architectures to build the Architecture Roadmap, which is a key step to define and prioritize the intermediate states between the Baseline and Target Architectures.
Option C is not correct because it does not follow the SAP Enterprise Architect framework at all. It suggests establishing change management processes for the management of the architecture artifacts, which is something that should be done earlier in the framework, not after creating the architecture designs. It also suggests handing over the artifacts to the implementation partner and rolling out the project, which is a premature and risky move that does not take into account the need for defining Transition Architectures, work packages, and Project/Rollout plan.
For more information on the SAP Enterprise Architect framework and its phases, you can refer to SAP Enterprise Architect | SAP Learning or SAP Certified Professional – SAP Enterprise Architect.

Explanation
The SAP Reference Business Architecture content provides a set of artifacts that can be used to describe the business architecture of an organization. These artifacts include:
Business Capability Model: This model describes the capabilities that an organization needs to have in order to achieve its business goals.
Business Process Model: This model describes the processes that an organization uses to deliver its products and services.
Business Data Model: This model describes the data that an organization uses to support its business processes.
Business Role Model: This model describes the roles that people play in an organization.
Product Map: This map shows how the different products and services that an organization offers are related to each other.
The SAP Reference Business Architecture content is a valuable resource for organizations that are looking to improve their business architecture. It provides a common language and set of concepts that can be used to describe the business architecture of an organization.
However, it is important to note that the SAP Reference Business Architecture content is just a starting point.
Organizations will need to tailor the content to their specific needs.

SAP provides several artifacts as part of the SAP Reference Solution Architecture content to guide and streamline solution design and implementation. The artifacts provided are aimed at delivering comprehensive architectural documentation to cover various aspects of the solution architecture. Option B includes the Solution Context Diagram, which provides a high-level view of the system’s environment and boundaries. The Solution Component Diagram gives an overview of the components and their interactions within the system. The Solution Application Use-Case Diagram describes how different users will interact with the application. The Solution Value Flow Diagram illustrates the value that flows through the system and between stakeholders.
Reference:
SAP documentation on Solution Architecture best practices.
Resources detailing the SAP Reference Architecture framework.

Explanation
The clean-core strategy is a SAP initiative to keep the core of SAP applications as clean as possible by moving customizations and extensions to the side-by-side layer. This allows SAP to more easily deliver new releases of applications without having to worry about breaking custom code.
The following are the benefits of following the clean-core strategy:
Stability: Extensions that are developed in accordance with the clean-core strategy are less likely to break when the underlying application is upgraded.
Maintainability: Extensions that are developed in the side-by-side layer are easier to maintain than extensions that are embedded in the core application.
Flexibility: The clean-core strategy allows for more flexibility in how extensions are developed.
Therefore, the clean-core strategy is a good way to ensure that future extensions to the Digital Core of the enterprise guarantee stable and reliable operations.
The clean-core strategy is a SAP initiative to keep the core of SAP S/4HANA as clean as possible by moving customizations and extensions to the side-by-side layer. This allows SAP to more easily deliver new releases of S/4HANA without having to worry about breaking custom code. The clean-core strategy ensures that extensions do not break an upgrade, and upgrades do not break an extension. This means that extensions are compatible with the latest version of SAP S/4HANA and do not require any changes or adaptations when a new release is applied. To achieve this, extensions must access SAP business objects only through well defined, upgrade-stable interfaces, such as public APIs, OData services, or events. These interfaces are documented and maintained by SAP and guarantee backward compatibility and stability across releases.
Verified References: 1: https://www.sap.com/products/rise/clean-core.html | 2:
https://blogs.sap.com/2023/02/22/s-4hana-clean-core-with-and-btp/

SAP Emarsys Customer Engagement is a cloud-based solution that helps businesses to create, manage, and deliver personalized marketing campaigns across multiple channels. It includes features for lead management, marketing campaign management, and recommendation management.
The Lead Business Process Module of the Lead to Cash E2E Process is responsible for managing leads and converting them into customers. SAP Emarsys Customer Engagement can be used to automate the lead management process, track lead progress, and identify opportunities for cross selling and upselling.
The other three options, SAP Sales Cloud version 2, SAP Omnichannel Promotion Pricing, and SAP Customer Data Cloud, are not as well-suited for the Lead Business Process Module of the Lead to Cash E2E Process.
SAP Sales Cloud version 2 is a cloud-based solution that helps businesses to manage sales opportunities and close deals. It does not have the same features for lead management and marketing campaign management as SAP Emarsys Customer Engagement.
SAP Omnichannel Promotion Pricing is a cloud-based solution that helps businesses to manage pricing and promotions across multiple channels. It does not have the same features for lead management and marketing campaign management as SAP Emarsys Customer Engagement.
SAP Customer Data Cloud is a cloud-based solution that helps businesses to collect, store, and analyze customer data. It does not have the same features for lead management and marketing campaign management as SAP Emarsys Customer Engagement.
Therefore, the best course of action is to use SAP Emarsys Customer Engagement to manage the Lead Business Process Module of the Lead to Cash E2E Process.

In the SAP Enterprise Architecture Framework, the opportunities & solution phase includes developing artifacts that help in visualizing the progression from current operations to the future state. The Business Architecture Roadmap outlines how business strategies will evolve, linking business goals with architectural changes. The Implementation Roadmap provides a detailed plan for the deployment of SAP solutions, including time frames and stages of implementation. The Migration Plan offers a comprehensive strategy for moving from legacy systems to modern SAP solutions, detailing the necessary steps for data migration and system transition.
Reference = These artifacts are described within the framework and guidelines for enterprise architecture development provided by SAP, focusing on ensuring that the solutions proposed are feasible, properly planned, and aligned with the business strategies and objectives.

Explanation
SAP Cloud Application Programming (CAP) is a programming model that allows ABAP developers to build extensions to SAP applications that follow the clean-core strategy. CAP provides a number of features that make it easy to build extensions that are stable, maintainable, and flexible.
Here are some of the features of CAP that make it a good choice for building extensions that follow the clean-core strategy:
Side-by-side extensibility: CAP extensions are deployed in the side-by-side layer, which means that they do not modify the core application. This makes CAP extensions more stable and maintainable than extensions that are embedded in the core application.
Open interfaces: CAP extensions expose their functionality through open interfaces. This makes it easy to integrate CAP extensions with other applications and services.
Cloud-based: CAP extensions are deployed in the cloud. This makes it easy to develop, deploy, and manage CAP extensions.
Therefore, SAP Cloud Application Programming (CAP) is a good choice for ABAP developers who want to build extensions to SAP applications that follow the clean-core strategy.
The other two options, SAP Classic Extensibility model and RESTful Application Programming (RAP), are not as good of a choice for building extensions that follow the clean-core strategy.
SAP Classic Extensibility model: The SAP Classic Extensibility model allows developers to modify the core application. This makes SAP Classic Extensibility extensions less stable and maintainable than CAP extensions.
RESTful Application Programming (RAP): RAP is a programming model that is used to build RESTful APIs. RESTful APIs are not a good fit for building extensions to SAP applications because they do not provide the same level of integration as CAP extensions.

Explanation
In a hybrid scenario, where business capabilities require services which partners have implemented in SAP BTP and an on-premise SAP S/4HANA system, the following SAP components and services are required to integrate such BTP partner services with the on-premise system:
SAP Cloud Connector: The SAP Cloud Connector is a software component that allows you to connect your on-premise SAP systems to SAP BTP. The Cloud Connector provides a secure connection between your on-premise system and SAP BTP, and it also makes your on-premise system available to applications and services in SAP BTP.
SAP BTP Destination Service: The SAP BTP Destination Service is a service that provides a single point of entry for accessing on-premise systems from SAP BTP. The Destination Service makes it easy to manage and secure connections to on-premise systems, and it also provides a way to federate data from different on-premise systems.
In order to integrate BTP partner services with an on-premise SAP S/4HANA system, you will need to install the SAP Cloud Connector on your on-premise system and register the Cloud Connector with SAP BTP. You will also need to create a destination in the SAP BTP Destination Service for your on-premise system. Once you have done this, you will be able to access the on-premise system from applications and services in SAP BTP.
It is important to note that you can also use other SAP components to integrate on-premise systems with SAP BTP. However, the SAP Cloud Connector and the SAP BTP Destination Service are the most commonly used components for this purpose.
To integrate BTP partner services with an on-premise SAP S/4HANA system, you need to use the SAP Cloud Connector, which is a reverse proxy that establishes a secure connection between your on-premise system and your SAP BTP subaccount5. The Cloud Connector acts as a bridge between your on-premise network and a trusted subaccount on SAP BTP6. It allows you to access resources in your on-premise network from applications running on SAP BTP without exposing your internal landscape to the internet7.
To simplify the configuration and consumption of the Cloud Connector connection, you can use the SAP BTP Destination Service, which is a service that allows you to define and manage destinations for accessing remote systems from applications running on SAP BTP8. A destination is a set of properties that contains information such as the URL, authentication method, proxy type, and additional parameters of a remote system9. By using the Destination Service, you can centrally manage and securely store the connection details of your on-premise system and consume them from your BTP partner services.
Verified References: 5:
https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/e6c7616abb5710148cfcf3e75d96
| 6:
https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/8d3b28a7c1644a1c9d1ee165ec0
| 7:
https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/e54cc8fbbb571014a4d9e7f02f9f
| 8:
https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/3cb7b81115c44cf594e0e363129
| 9:
https://help.sap.com/viewer/cca91383641e40ffbe03bdc78f00f681/Cloud/en-US/e54f70d327154aa0a4ba36ce7ac4

Explanation
The customer’s architecture guideline calls for following a “cloud-first” approach, but this does not mean that all solutions must be deployed in the cloud. In some cases, private cloud or on-premise options may be necessary to meet the customer’s data protection requirements.
For example, if the customer’s subsidiary in China requires that data be stored within China, then a private cloud solution in China may be the best option. Similarly, if the customer’s other subsidiaries have different data protection requirements, then a hybrid solution that combines cloud and on-premise deployments may be necessary.
The Enterprise Architect must carefully consider the customer’s specific requirements and constraints before making a decision about the deployment environment.
Here are some of the factors that the Enterprise Architect should consider:
The customer’s data protection requirements: The Enterprise Architect must understand the customer’s specific data protection requirements and ensure that any solution meets those requirements.
The availability of cloud-based solutions that meet the customer’s requirements: Not all cloud-based solutions meet the same data protection requirements. The Enterprise Architect must ensure that the cloud-based solutions that are being considered meet the customer’s requirements.
The cost of different deployment options: The Enterprise Architect must consider the cost of different deployment options, including cloud, private cloud, and on-premise.
The scalability and performance requirements of the solution: The Enterprise Architect must ensure that the solution meets the customer’s scalability and performance requirements, regardless of the deployment environment.
By carefully considering all of these factors, the Enterprise Architect can make a decision about the deployment environment that meets the customer’s specific requirements and constraints.

Considering Wanderlust’s product range and business model, which targets individual customers and offers a wide range of electric car combinations, the Lead to Cash-B2C with Make to Stock variant would be suitable for orders that can be met from existing stock. Similarly, the Lead to Cash-B2C with Make to Order variant would fit the business model when an individual customer orders a combination not available in stock, necessitating production scheduling. Both variants cater to the business-to-consumer (B2C) model and account for the direct sales approach to individual customers.
Reference = These variants would be documented in SAP’s Business Process Architecture content, which includes various Lead to Cash process scenarios, adjusted for different business contexts.

For ABAP developers looking to build SAP extensions that adhere to the clean-core strategy, the recommended programming model is the RESTful Application Programming (RAP) model. RAP is designed specifically for developing SAP Fiori applications and services with a focus on maintaining a clean and stable core while allowing for extensions.
RESTful Application Programming (RAP) offers a modern ABAP programming model that supports development both in the cloud and on-premise. It is centered around services that are exposed through RESTful APIs, making it ideal for creating clean, decoupled extensions that do not interfere with the core S/4HANA system. This approach supports the clean-core strategy by enabling developers to create extensions that communicate with the core system via stable, well-defined APIs without modifying the core system itself.
Option A, SAP Cloud Application Programming (CAP), although a robust model for cloud-native application development, is not specific to ABAP and does not inherently align with the ABAP developer environment. Option B, the SAP Classic Extensibility model, often involves direct modifications to the core system, which contradicts the principles of the clean-core strategy.
:
SAP documentation on RESTful Application Programming Model.
SAP community articles and guides on developing with RAP.