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Unit3
Supakorn Kungpisdan
[email protected]
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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)
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 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
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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
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Type
Use
DIA
Responsible for dialog requests
UPD
Responsible for update
UPD2
Exclusively responsible for less timecritical 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
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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 DBindependent.
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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)
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