SAP Architecture overview
SAP’s architecture overview ties together the pieces that make an SAP system work: the three-tier client-server model, the application-server work processes, instances, and the integration layer. This page is the map; the detailed architecture lessons drill into each part.
SAP runs as three tiers, SAP GUI or Fiori on top, application servers whose work processes run the ABAP logic under a dispatcher, and one database, HANA for S/4HANA. A system is one or more instances sharing that database, divided into clients as isolated tenants. RFC, BAPI, IDoc and ALE connect other systems; DEV, QAS and PRD carry change.
- Watch out: Blurring the three tiers.
The three tiers
- Presentation: SAP GUI or Fiori in the browser.
- Application: app servers running work processes that execute business logic.
- Database: one database (HANA for S/4HANA) holding all data.
The application server up close
The application tier is where SAP’s logic runs, as ABAP (and some Java) in work processes coordinated by a dispatcher. Different work-process types handle interactive dialog steps, background jobs, database updates, locking and printing, so one system serves users and batch work together.
Systems, instances and clients
A system is made of one or more instances (units of work processes and memory) sharing a database, and is divided into clients (isolated data tenants). This structure supports scaling (add instances) and isolation (separate clients for config, test and data).
Integration and the landscape
Around the core sit the gateway and mechanisms (RFC, BAPI, IDoc, ALE) for talking to other systems, and the landscape (DEV/QAS/PRD with transports) for safe change. Together these define how SAP runs, scales and connects.
Common pitfalls
- Blurring the three tiers.
- Confusing system, instance and client.
- Ignoring the integration layer that connects SAP to everything else.