SAP Architecture Overview

Architecture describes how the parts of an SAP system are organized and how they talk to each other. Think of it like the blueprint of a building. Before workers lay a single brick, architects draw plans showing where every room, corridor, and pipe will go. SAP architecture is the same concept — it shows how data flows, where it gets stored, and which layer handles which job.

Understanding SAP's architecture helps you make better integration decisions. When you know where data lives and how layers communicate, you can build faster, more reliable connections.

The Three-Tier Architecture

SAP uses a classic three-tier architecture. Each tier has a specific role:

┌──────────────────────────────────────┐
│        TIER 1: Presentation Layer    │
│   (Web browser, SAP GUI, Fiori app)  │
│        What the user sees            │
└──────────────────┬───────────────────┘
                   │ User request goes down
┌──────────────────▼───────────────────┐
│        TIER 2: Application Layer     │
│   (SAP Application Server - ABAP)    │
│        Where business logic runs     │
└──────────────────┬───────────────────┘
                   │ Processed data goes down
┌──────────────────▼───────────────────┐
│        TIER 3: Database Layer        │
│   (SAP HANA, Oracle, SQL Server)     │
│        Where all data is stored      │
└──────────────────────────────────────┘

Tier 1 – Presentation Layer

This is everything the user interacts with. It could be the traditional SAP GUI desktop client, a browser-based SAP Fiori application, or a mobile app. The presentation layer never touches the database directly. It only talks to the application layer.

Tier 2 – Application Layer

This is the brain of the system. It receives requests from users, applies business rules, calculates results, and sends instructions to the database. The application layer in a classic SAP system runs on the SAP NetWeaver Application Server (often called AS ABAP). In modern SAP S/4HANA, parts of this logic have moved into the database layer itself.

Tier 3 – Database Layer

This layer stores all data permanently. In modern SAP systems, the database is almost always SAP HANA — SAP's own in-memory database that processes data at very high speeds. Older SAP systems may use Oracle, Microsoft SQL Server, or IBM DB2.

What Is SAP NetWeaver

SAP NetWeaver is a technology platform that runs underneath SAP applications. Think of it as the foundation under a house. The house (SAP ERP, SAP CRM, etc.) sits on top of NetWeaver. NetWeaver provides services that all SAP applications share, such as:

• User authentication and access control
• Web service publishing
• Integration with other systems using Web Services
• ABAP and Java runtime environments

Many integration points in SAP — especially older ones — go through NetWeaver. When you see terms like SAP PI (Process Integration) or SAP PO (Process Orchestration), those are NetWeaver-based integration products.

SAP Landscape: Dev, QA, and Production

Every SAP installation typically has three separate environments:

[Developer writes code] → [DEV System] → [QA System] → [PROD System]
                             (Sandbox)     (Testing)     (Live Business)

• DEV (Development) – Where developers write and test new configurations. Changes here do not affect real business data.
• QA (Quality Assurance) – A copy of the production system. Business users test changes here and confirm everything works before go-live.
• PROD (Production) – The live system. Real employees use it daily. Changes only go here after passing QA.

This three-system landscape protects the business. A mistake in DEV is harmless. The same mistake in PROD could stop an entire warehouse operation.

The SAP HANA In-Memory Database

Traditional databases store data on hard disks. Reading from a disk takes milliseconds. SAP HANA stores data in RAM (memory), which is thousands of times faster. This speed matters most for reporting and analytics where SAP reads millions of rows instantly.

A helpful analogy: Imagine finding a word in a 1,000-page printed book versus using the search feature in a digital document. The printed book is the hard disk database. The digital search is SAP HANA.

Client Concept in SAP

Inside one SAP system, multiple independent companies can exist as separate clients. Each client has its own data, settings, and users. They share the same software installation but never see each other's data.

For example, a company group with three subsidiaries can run all three inside one SAP system. Finance Team A sees only Client 100 data. Finance Team B sees only Client 200 data. The IT team manages one system instead of three.

Transport System

SAP uses a Transport Management System (TMS) to move configurations from DEV to QA to PROD. Instead of copying files manually, developers package changes into a transport request. TMS moves that package through the landscape in a controlled, traceable way.

This matters for integration because every integration flow you build must go through the same transport process before it goes live in production.

How This Applies to Integration

When you build an integration between SAP and an external system like Salesforce, your integration flow runs on the SAP Integration Suite — which sits outside the three-tier stack as a separate cloud service. The integration flow calls SAP's application layer through APIs or IDocs. The application layer does its processing, saves data in the database, and returns a response to the integration flow.

[Salesforce] → [SAP Integration Suite] → [SAP App Layer] → [SAP HANA DB]
                  (Cloud middleware)         (Business logic)   (Data storage)

Knowing this path helps you debug problems. If data is not reaching SAP, you check each step: Did it leave Salesforce? Did the integration suite receive it? Did the application layer accept it? Did the database save it?