SAPTEC 1

Unit3

Supakorn Kungpisdansupakorn@mut.ac.th

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Business Example

In the course of implementing an SAP system, you need to establish the architecture of SAP systems and how you are going to distribute the required SAP system processes among the available hardware

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Introduction

SAP systems are used for mapping business processes or business applications.

These applications should be implemented independent of the hardware environment used (OS, DB) to the greatest extent possible.

SAP Web AS Application Server provides two runtime environments: ABAP runtime environment Java runtime environment

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Introduction (cont’d)

ABAP (Advanced Business Application Programming) is developed by SAP Use ABAP workbench for developing SAP application

Since Web AS 6.20, SAP provides Java runtime environment Integrate J2EE and called “SAP Web AS Java”

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Client and Server: Terminology Definition

Hardware-oriented view Server is a central server in

a network providing resources for client (workstation)

Software-oriented view Both client and server are

processes

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Client/Server Configuration for SAP Systems

The following processes are required for operating business application software: Presentation processes (e.g. for displaying screens) Application processes (e.g. for executing application

programs) Database processes (e.g. for managing and organizing

DB data)

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Client/Server Configuration for SAP Systems (cont’d)

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Client/Server Configuration for SAP Systems (cont’d) Single tier

Used for tests and demonstrations Incur extra cost for increased users

Two tier With distributed presentation processes, it can maintain good

performance for a significantly higher number of users Load from presentation processes is distributed to the various

front-end computers. So it does not influence the performance of the DB host

Three tier Distribute application layer to several hosts to reduce

bottlenecks More that three tier: may include web server level

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Architecture of ABAP Applications

BSP = business server page used for developing web applications on SAP Web AS Application Server

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Architecture of Java Applications

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SAP Web AS Processes

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SAP Web AS Processes (cont’d)

In ABAP environment, ABAP dispatcher manages different types of work processes

(WP) Dialog WPs fulfill all requests.

Every dispatcher requires at least two dialog WPs Spool WPs pass sequential data flow to printers

Can have more than one spool per dispatcher Update WPs execute update requests

Need at least one update per dispatcher Can have more than one per dispatcher

Background WPs execute programs that run without interacting with the user

Need at least 2 backgrounds per SAP system Enqueue WP administers the lock table in shared memory

Need only 1 enqueue per system

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SAP Work Processes

Type Use

DIA Responsible for dialog requests

UPD Responsible for update

UPD2 Exclusively responsible for less time-critical update (optional)

BGD Executes background jobs

SPO Processes output requests

ENQ Responsible for locks

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SAP Web AS Processes (cont’d)

ABAP runtime system provides additional services for internal and external communications: Message Server (MS) handles the communications between

the distributed dispatchers within the ABAP stack of an SAP system

One dispatcher per instance Enabling scalability of several parallel application servers

Gateway Server (GW) enables communications between SAP systems, or between SAP systems and external application systems

Internet Communication Manager (ICM) enables SAP systems to communicate directly with the Internet

Direct HTTP request from an SAP system to a web server and send the response back to the SAP system

Can have ICM per instance

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The instance

Instance is an administrative unit that combines SAP system components providing one or more services

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Instance in the ABAP+Java Environment

JCo = Java Connector

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Instance in the ABAP+Java Environment (cont’d)

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Types of the SAP Web AS

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Possible User Requests in the SAP System

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Dialog Processing in the SAP System

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Structure of a Work Process

Work processes execute dialog steps for applications programs

A work process has a task handler that coordinates the actions within a work process, two software processors and a database interface

SAP application programs differentiate between user interaction and processing logic

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Structure of a Work Process

The user interactions are technically realized using screens, also called dynpros (dynamic programs) Consist of screen image and underlying flow

logic. Screen flow logic is divided into PBO (process before output): is processed before

the screen image is sent and PAI (process after input): is processed after a user

interaction on the screen

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Processing flow for dialog steps

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Communication with the Database

Within ABAP, you can use SAP Open SQL to access the application data in the database, regardless of the RDBMS used.

The database interface, which is part of every WP on the SAP Web AS, translates Open SQL statements from ABAP into the corresponding SQl statements for the specific DB used (Native SQL).

This allows ABAP programs to be DB-independent.

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Communication with the Database (cont’d)

Native SQL commands can be used to directly in ABAP without local buffer and db interface

However, you can no longer maintain the platform independence of the affected programs

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Communication with the Database

The SAP Web AS Database Interface

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DB Transactions and SAP Transactions

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Fundamentals of Enqueue Processing in SAP Systems

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Requesting a Lock Entry

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Update Processing

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Update Processing (cont’d)