SAP Architecture , SAP Landscape & SAP Client

SAP Architecture

SAP is implemented using 3 Tier Architecture. It consists of three servers:
1. Application Server
2. Database Server
3. Presentation server

All the SAP programs and applications run on application server. They act as an interface between Database and Presentation servers.
Database servers are the centralized server where all the data is stored. They can only be accessed via requests to application servers.
Presentation servers are the system, typically our desktops, which are used to connect to application servers. It’s the presentation server where we run the GUI, e.g. SAP GUI, Web GUI, etc.

SAP Landscape

SAP landscape is the setup or arrangement of SAP servers. There are 3 systems in SAP landscape:
Development System (DEV client, sandbox)
Quality system (QAS client,  user training)
Production system (PROD client )

The name and numbering of systems is solely on basis of business requirements and implementation strategy.
Whatever you do on Development or Sandbox client doesn’t have any effect on other systems or clients.
All the developments, configurations and customizations are first done on development systems and organized under transport requests. They are thoroughly tested on quality systems and eventually loaded onto the production system (Live Systems).

Transport management system co-ordinates the movement of development objects, customizations and configurations.
SAP Technical consultants usually develop RICEF objects and organize them under Transport tasks and requests. Once they objects are thoroughly tested by Functional consultants on QAS systems, the transport requests are released and developments & customizations are transported across to Production system.
Production systems are live systems. They contain live user data, which is periodically loaded onto the QAS systems.

SAP Clients:

 A client is an independent unit within the R/3 system or an area in the system with data on which a user works.

We have to do client copy right after installation of the software as our first job to begin the technical phase of implementation. We have to copy from one of the standard clients available. We can use copied clients for testing, training or for starting real customization.

Clients are represented by 3 digits NNN. So it can range from 000 to 999. Out of which 3 clients are default, Standard clients: 000,001,066. So we can create at max 997 clients for our own purpose.

Client 000: master client

 Client 000 contains a simple organizational structure of a test company and includes parameters for all applications, standard settings, configurations for the control of standard transactions and examples to be used in many different profiles of the business applications. For these reasons, 000 is a special client for the R/3 system since it contains the client−independent settings. 

Client 001: customizing or development client

. This client is a copy of the 000 client including the test company. This client’s settings are client-independent if it is configured or customized. This client is reserved for the activities of preparing an R/3 system for the production environment. The customers of the SAP normally use this client as a source for copying other new clients. 

Client 066: SAP Access Client.

SAP accesses the customer systems using this client to perform early watch service.