How This Course Fits into the SAP S/4HANA Development Landscape

The technologies in this course are not separate topics.

They fit together as part of SAP's modern approach to building and extending business applications around SAP S/4HANA.

The simplest way to think about it is:

SAP S/4HANA
=
SAP's standard business processes and business data

ABAP Cloud
=
the modern ABAP development model used to build
upgrade-stable applications and extensions

CDS + RAP
=
the main building blocks for modeling data
and transactional business objects

OData + Fiori
=
ways to expose and consume those business objects

---

1. The big picture

SAP S/4HANA already contains business objects and processes such as:

Business Partner
Sales Order
Purchase Order
Material / Product
Journal Entry
Billing Document
Production Order

As an ABAP developer, you normally do not rebuild these from scratch.

Instead, you may:

extend an SAP process
build a new custom business object
create a new application
integrate S/4HANA with another system

A modern SAP extension should use supported, released interfaces rather than depend directly on internal SAP implementation details.

That is one of the main ideas behind:

ABAP Cloud
Clean Core
released APIs
RAP

---

2. How the technologies from this course connect

A typical custom RAP application looks like this:

                User / External System
                         │
                         ▼
                  Fiori / API Client
                         │
                         ▼
                     OData V4
                         │
                         ▼
              RAP Business Service
                         │
                         ▼
             RAP Business Object
              ├─ actions
              ├─ validations
              ├─ determinations
              ├─ authorization
              └─ feature control
                         │
                         ▼
                       CDS
                         │
                         ▼
              Persistence / SAP API
                         │
                         ▼
                    SAP HANA

Each course topic has a place in that picture.

Course concept	What it does
ABAP	Implements application and business logic
ABAP SQL	Reads and writes data you are allowed to access
CDS	Models business data and relationships
RAP	Adds transactional business-object behavior
EML	Lets ABAP code consume RAP Business Objects
Validation	Prevents invalid business state
Determination	Calculates or defaults data automatically
Action	Represents a named business operation such as Approve or Cancel
Authorization	Controls what a user is allowed to do
OData	Exposes the business service to other consumers
Fiori	Provides the user interface
SAP HANA	Stores the underlying data

The important idea is:

CDS describes the business data. RAP controls how that business data may be changed.

---

3. Where SAP S/4HANA fits

In the course, you create your own objects such as:

ZRESV_###
ZR_RESERVATION_###

That is useful because you control the complete example.

In a real S/4HANA project, there are two common situations.

Situation A — your application owns the data

For example, your company needs a completely new internal Risk Review object.

You may create:

Custom Persistence
       ↓
Custom CDS
       ↓
Custom RAP BO
       ↓
OData Service
       ↓
Fiori App

This is very similar to the Reservation application built in the course.

Situation B — S/4HANA already owns the data

For example:

Sales Order
Purchase Order
Business Partner
Material

You should normally work through an SAP-released API, CDS entity, RAP interface, or extension point.

Conceptually:

Your Extension
      ↓
Released SAP Interface
      ↓
S/4HANA Business Object
      ↓
SAP-managed data

You should not think:

"I found the SAP database table,
so I will update it directly."

The SAP business object may contain important:

validations
status logic
authorization
document flow
accounting logic
events
side effects

that a direct table modification would bypass.

---

4. On-stack vs side-by-side development

This is one of the most important distinctions to understand.

On-stack developer extensibility

Your ABAP Cloud extension runs inside the S/4HANA ABAP environment.

┌──────────────────────────────┐
│         SAP S/4HANA          │
│                              │
│ Standard SAP Business Logic  │
│            │                 │
│     Released SAP APIs        │
│            │                 │
│     Custom ABAP Cloud        │
│     CDS / RAP Extension      │
└──────────────────────────────┘

This is useful when the extension belongs closely to the S/4HANA process.

Side-by-side extensibility

Your application runs separately on SAP BTP.

┌──────────────────────┐
│     SAP S/4HANA      │
│                      │
│ Standard Processes   │
└──────────┬───────────┘
           │
     Released API
       or Event
           │
           ▼
┌──────────────────────┐
│       SAP BTP        │
│                      │
│ ABAP Cloud App       │
│ CDS / RAP            │
│ Custom Persistence   │
└──────────────────────┘

The two systems have separate lifecycles.

They communicate through supported integration contracts.

---

5. Where your BTP Trial fits

The SAP BTP ABAP Trial used in this course is not an S/4HANA system.

It is its own ABAP environment.

When you create:

ZRESV_###

you are creating a table in your BTP ABAP environment.

You are not adding a table to S/4HANA.

What Trial gives you is the ability to learn the same important development model:

ABAP Cloud
CDS
RAP
EML
OData
ADT

So the skills transfer.

The difference in a real S/4HANA project is mainly:

where your code runs

and

how it reaches SAP business data

---

6. Two real-world examples

Example 1 — custom quality review inside S/4HANA

A manufacturer needs a small custom quality-review application connected closely to an existing manufacturing process.

A possible architecture is:

S/4HANA Manufacturing Data
           │
           ▼
   Released SAP Interface
           │
           ▼
   Custom ABAP Cloud Code
           │
           ▼
      Custom RAP BO
           │
           ▼
       OData V4
           │
           ▼
       Fiori App

Here, the extension runs on the S/4HANA stack.

The techniques from this course apply directly:

CDS
RAP
validations
actions
authorization
OData
Fiori

---

Example 2 — supplier application on SAP BTP

A company wants a supplier-facing application that uses Purchase Order information from S/4HANA but also stores its own:

supplier comments
review status
external documents
approval information

A possible architecture is:

SAP S/4HANA
Purchase Order
      │
      ▼
Released API / Event
      │
      ▼
SAP BTP ABAP Environment
      │
      ├─ Custom Persistence
      ├─ CDS
      ├─ RAP
      └─ Business Logic
      │
      ▼
OData / Application

In this case:

S/4HANA owns the Purchase Order

BTP owns the extension-specific data

That separation is important.

---

7. Where Clean Core fits

Clean Core does not mean:

no custom code

It means custom development should avoid unnecessary dependencies on SAP internals.

A simplified comparison is:

Tightly coupled approach

Custom Code
    ↓
Internal SAP Table / Internal Object

versus:

Clean Core-oriented approach

Custom Extension
      ↓
Released SAP API / Extension Point
      ↓
SAP S/4HANA

Released contracts make it easier for SAP to change internal implementation without breaking customer extensions.

That is why modern SAP development places so much emphasis on:

released APIs
ABAP Cloud
RAP
extension points
side-by-side applications

---

8. How your course progression maps to a real application

The course gradually builds this architecture:

Database / Persistence
        ↓
       CDS
        ↓
RAP Business Object
        ↓
Behavior
  ├─ CRUD
  ├─ validations
  ├─ determinations
  ├─ actions
  ├─ authorization
  └─ draft
        ↓
Projection
        ↓
Service Definition
        ↓
Service Binding
        ↓
OData V4
        ↓
Fiori / API Consumer

In a real S/4HANA project, the bottom of the diagram may change.

If you own the data:

RAP
 ↓
your custom persistence

If SAP owns the data:

your extension
 ↓
released SAP interface
 ↓
S/4HANA business object

That is the connection between the training environment and real SAP development.

---

9. The main idea to remember

You do not need to memorize every SAP product and layer.

Remember this:

SAP S/4HANA
=
the core ERP business system

ABAP Cloud
=
the modern ABAP development model

CDS
=
the business data model

RAP
=
the transactional business-object model

EML
=
ABAP-to-RAP consumption

OData
=
service exposure

Fiori
=
the user experience

SAP BTP
=
a platform where side-by-side extensions
and integrations can run

And the most important architectural rule is:

Work through stable business contracts rather than coupling custom code directly to SAP's internal implementation.

That is how the technologies taught in this course fit together in the SAP S/4HANA development landscape.