ABAP Programs in AS ABAP – Study Notes
Overview
ABAP programs are executed on the Application Server ABAP (AS ABAP) of an ABAP system. The AS ABAP represents the application layer.
Key Concepts
System ID
AS ABAP is identified by a system ID
This ID is also the name of the entire ABAP system
Users log on to AS ABAP using a user name
Main Components of AS ABAP
1. AS Instance (Application Server Instance)
ABAP program execution takes place in AS Instances
One or more AS Instances can be instantiated for an AS ABAP
Multiple AS Instances are usually distributed across several host computers
AS Instances communicate using a message server (exactly one per AS ABAP)
2. Work Processes
Each AS Instance uses work processes to execute ABAP programs.
Types of Work Processes:
Type Purpose
Dialog Interactive user requests
Enqueue Lock management
Background Batch processing
Spool Output management
Update Database updates
Key Characteristics:
Each work process is logged on to the standard database as a database user
Uses a standard connection
User is assigned the ABAP database schema
System programs, system tables, application programs, and application tables are stored in the ABAP database schema
3. Communication Components
Connect AS Instances with:
Presentation layer of the ABAP system
Other systems (another AS ABAP or external systems)
Communication Components:
Component Purpose
ICM (Internet Communication Manager) Browser-based UIs (SAPUI5, Web Dynpro), Internet
RFC Interface Link to other systems
Dispatcher Link to SAP GUI
Protocols Used:
HTTP, HTTPS
TCP
SAP RFC protocol
ABAP Program Execution Model
ABAP program execution is organized in sessions, which can access different memory areas.
Related Topics:
[Sessions and Memory Areas]
[User Sessions]
[Programs in the Internal Session]
Architecture Summary
┌─────────────────────────────────────────────────────────┐
│ ABAP System │
│ ┌───────────────────────────────────────────────────┐ │
│ │ AS ABAP (Application Layer) │ │
│ │ ┌─────────────┐ ┌─────────────┐ │ │
│ │ │ AS Instance │ │ AS Instance │ (Multiple) │ │
│ │ │ ┌─────────┐ │ │ ┌─────────┐ │ │ │
│ │ │ │Work │ │ │ │Work │ │ │ │
│ │ │ │Processes│ │ │ │Processes│ │ │ │
│ │ │ └─────────┘ │ │ └─────────┘ │ │ │
│ │ └─────────────┘ └─────────────┘ │ │
│ │ ↑ Message Server ↑ │ │
│ └───────────────────────────────────────────────────┘ │
│ ┌───────────────────────────────────────────────────┐ │
│ │ Database Layer (ABAP Database Schema) │ │
│ └───────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────┘
Key Takeaways
AS ABAP is the application layer where ABAP programs run
AS Instances contain work processes that execute ABAP code
Work processes are specialized: dialog, enqueue, background, spool, update
Communication components (ICM, RFC, Dispatcher) connect the server to users and other systems
Program execution is organized in sessions with access to different memory areas
Content Source: https://help.sap.com/
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