Discussing the SAP Three-Tier Client Server Architecture

Objective

After completing this lesson, you will be able to describe SAP’s three-tiered client/server architecture and supported platforms.

Three-tier Client/Server Architecture

Introduction

In the previous lesson, you learned about SAP's long history of developing ERP software solutions, culminating with the most current release of its flagship product SAP S/4HANA.

In this lesson, you will explore the system architecture that supports SAP S/4HANA and define an SAP system.

SAP's Three-tiered Architecture

Most SAP applications run in a three-tiered client/server environment. Instead of using a single execution process, the application consists of multiple processes, running across multiple computers (hosts). These processes cooperate across a network to perform the necessary processing for the application.

Each tier has its own function to perform, and typically runs on separate hosts. This architecture provides multiple benefits, including flexibility, high performance, extensibility, and ease of development.

Diagram that provides an outline of Three-tier Client/Server Architecture

When SAP moved from Business Suite, its old ERP solution to SAP S/4HANA, it kept the three-tiered architecture. However, many components of that architecture continue to evolve.

SAP systems support a wide variety of hardware vendors and configurations. The hardware that a specific system will run on depends on the particular customer situation. The customer has a choice of the following:

  • Cloud or on-premise systems
  • Numerous hardware vendors
  • Different machine types and capacities
  • Various supported operating systems

Components of Three-tiered Architecture for SAP S/4HANA

SAP's three-tiered architecture for SAP S/4HANA consists of the following:

  1. The database (data storage) layer
  2. The application layer
  3. The presentation layer

Watch the following video to learn more about the system architecture for SAP ABAP applications like S/4HANA.

The Database, Application, and Presentation Layers

Overview

The following image highlights the database layer in red, showing its place in the three-tier client/server architecture.

The database layer is highlighted in red, showing its place in the three-tier architecture

The Database Layer provides data storage and additional application functionality. Data is stored in a series of tables in a relational database.

When you install an SAP application, the installation program will create all tables, indexes, views, and so on, used by the application. SAP applications use SQL to access the data.

Additionally, the database engine provides additional analytic and application processing capability. This processing is utilized for data-intensive operations.

Evolution

Historically, SAP supported a variety of relational databases, but currently, all future development is focused on SAP HANA.

For example, SAP Business Suite supported several database management systems, including SAP HANA, SAP ASE, Oracle, MS SQL Server, and IBM DB2. However, to do this, it used ANSI SQL, which limited the ability of SAP ABAP to take advantage of many database-specific features. Thus, Business Suite used the database only for data storage.

SAP S/4HANA runs only on SAP HANA. It uses SQLScript, SAP S/4HANA's proprietary dialect of SQL, to access the database. This enables SAP S/4HANA to use the complete set of HANA features, functions, and engines.

Hardware

The database layer runs on one or more server hosts. These hosts tend to be larger and have more resources than the application layer hosts. While the application layer and the database layer can run on the same hosts, this is typically only done for smaller customers. For larger systems, it is more effective and lower cost to run the two layers on separate hosts.

The Application Layer

The following image highlights the application layer in red, showing its place in the three-tier client/server architecture.

The application layer is highlighted in red, showing its place in the three-tier architecture

In SAP S/4HANA, the application layer is delivered by ABAP platform. ABAP platform is SAP's technical platform, which is used for developing and running business applications in the SAP environment. ABAP, short for Advanced Business Application Programming, is a proprietary programming language developed by SAP and used to develop SAP applications.

SAP delivers applications using a component model, grouping related programs and objects together along functional lines. As a result, the application logic on this tier is typically focused on routine functional processing, interaction with the presentation layer, interaction with the database layer, and security. Application components are typically deployed on multiple application server instances, which allow for easy scaling of the application.

We will discuss the SAP instance in more detail in a later lesson.

Evolution

Over time, the capabilities of the application layer have evolved as technology and functional requirements have evolved. While ABAP has been the primary platform for developing SAP applications, the advent of the Internet necessitated new innovations in programming in order to leverage the World Wide Web. In response to this need, SAP introduced WebDynpro.

SAP WebDynpro is a user interface technology developed by SAP for building business web applications in the ABAP and Java programming languages. It allows developers to create web-based applications with a rich and interactive user interface and integrates seamlessly with SAP systems and data. It is widely used for developing custom web applications within the SAP environment.

Today, mobility is critical for many businesses. With SAP S/4HANA, SAP introduced SAP Fiori and incorporated OData Services for development of new SAP applications. SAP OData (Open Data Protocol) is a standardized protocol for building and consuming certain APIs. SAP applications use OData to enable integration and communication between different systems and services.

OData provides a uniform way to expose and interact with data through HTTP-based services, making it easier to create, consume, and manage data-driven applications. With SAP Fiori, SAP was able to standardize the user experience and make SAP functionality seamless across any device, laptop, tablet, and desktop.

Hardware

ABAP platform, along with the application components, may be deployed on multiple hosts. Each host provides the requisite hardware resources (CPU, memory, connectivity, and so on) to support one or more instances of the application server logic. The number of hosts that can be supported is practically unlimited, and a large number of hosts can reduce the cost of providing signification amounts of CPU, memory, and other hardware resources. Currently, SAP supports on-premise, cloud, and hybrid deployments of SAP S/4HANA.

The Presentation Layer

The following image highlights the presentation layer in red, showing its place in the three-tier client/server architecture.

The presentation layer is highlighted in red, showing its place in the three-tier architecture

The presentation layer provides the user interface (the front-end client) that is accessed by the end-user. The presentation layer is typically represented by a thin-client, in that the client contains no application logic or data storage capability. It simply facilitates accessing the application functionality at the application layer.

SAP supports several user interfaces, including SAP GUI, SAP Business Client, and SAP Fiori. Depending upon the interface, the front-end may run on one or more end-user platforms such as a laptop, desktop, tablet, or mobile phone.

Evolution

Prior to SAP S/4HANA, the primary front-end client consisted of a desktop application called the SAP GUI. SAP GUI is the universal client for performing application functions, administration, monitoring, and development in an SAP ABAP application. The SAP GUI renders dynpro screens that have been developed for ABAP programs.

There are multiple flavors of the SAP GUI:

  • Windows - a desktop component designed for the Windows operating system
  • Java - a desktop component that supports multiple operating systems
  • HTML - a web browser component that supports any HTML5-compatible web browser

To support SAP applications developed using SAP WebDynpro, such as SAP GRC Access Control, SAP delivers the SAP Business Client. The SAP Business Client is an application capable of rendering browser-based screens using HTML.

Additionally, the Business Client can also render standard SAP GUI dynpro based screens within a web browser through the SAP GUI for HTML. For the first time, end users using the SAP Business Client could have a single point of entry for different SAP business applications.

With the release of SAP S/4HANA, SAP introduced SAP Fiori, a new tile-based user interface utilizing HTML5 and running on a web browser. SAP Fiori is now the primary presentation layer interface designed to provide a role-based, adaptive, and coherent user experience for SAP Applications. Similar to the SAP Business Client, the SAP Fiori Launchpad has the capability to render screens created using different tools.

New applications developed for S/4HANA are created and designed as native SAP Fiori applications and cannot be accessed through the SAP GUI or SAP Business Client. However, standard ABAP application and WebDynpro application screens can be rendered by the Fiori Launchpad, which gives SAP users a single point of entry for all SAP applications.

Each of these user interfaces will be discussed in more detail in a later lesson.

Hardware

The client typically runs on an individual machine, specific to the end user. This may be anything from a desktop computer to a tablet to a hand-held device. A variety of operating systems are supported, such as Windows, UNIX, or MacOS.

If the presentation layer is running on a supported web browser, then almost any hardware and operating system combination is available.

Summary

You are now able to describe SAP's three-tiered client/server architecture.

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