In SAP R/3 architecture, what are presentation, application, and database servers, and what role does each layer play?

Introduction / Context:
SAP R/3 uses a three tier architecture with clearly defined roles for presentation, application, and database servers. This question digs a little deeper into what each server type actually does. For business technology interviews, being able to explain these roles clearly is important.

Given Data / Assumptions:

• We are discussing SAP R/3 or similar three tier SAP systems.
• The tiers are named presentation, application, and database.
• Each tier has a distinct function in handling user interaction, business logic, and data.

Concept / Approach:
The presentation server runs the SAP GUI or other front end components that users see and interact with. It sends user input to the application server and displays output. The application server hosts the SAP runtime, executes ABAP and other business logic, manages sessions, and coordinates database access. The database server is responsible for storing and retrieving persistent data in relational tables and ensuring data integrity through transactions, locking, and logging. Separating these layers enables scalability and flexibility.

Step-by-Step Solution:
Step 1: Identify the function of the presentation server as handling user interface and interaction.Step 2: Identify the function of the application server as executing programs, processing business rules, and coordinating work.Step 3: Identify the function of the database server as storing, retrieving, and protecting persistent business data.Step 4: Compare the options and find the one that correctly assigns these roles to the three server types.Step 5: Option A accurately reflects the standard SAP explanation and is therefore correct.

Verification / Alternative check:
SAP training materials list these functions explicitly when introducing the three tier architecture. Diagrams show users connecting to the presentation layer, which communicates with the application layer, which in turn sends structured queries to the database layer. No reputable source claims that all three servers are identical or that the database server is responsible for the user interface.

Why Other Options Are Wrong:
Option B reverses responsibilities and incorrectly states that the presentation server stores data and the database server displays the interface. Option C denies the functional separation that is fundamental to the architecture. Option D simply lists unrelated devices and is clearly incorrect.

Common Pitfalls:
Some learners confuse the location of business logic, thinking it might be split across client and server. In SAP R/3, core logic is on the application server, while the GUI focuses mainly on presentation. Others underestimate the importance of the database server in maintaining transactional consistency and performance. A clear understanding of each layer helps when discussing performance tuning, security, and system scaling.

Final Answer:
The presentation server provides the SAP graphical user interface to users, the application server executes business logic and ABAP programs, and the database server stores and retrieves all persistent business data.