SAP R/3 ARCHITECTURE FAQ
1. What guarantees the integration of all application modules?
The R/3 basis system guarantees the integration of all application modules. The R/3 basis s/w provides the run time environment for the R/3 applications ensures optimal integration, defines a stable architectural frame for system enhancements, and contains the administration tools for the entire system.
One of the main tasks of the basis system is to guarantee the portability of the complete system.
2. What are the central interfaces of the R/3 system?
Operating system Interface.
3. Which interface controls what is shown on the p.c.?
4. Which interface converts SQL requirements in the SAP development system to those of the database?
5. What is SAP dispatcher?
SAP dispatcher is the control agent that manages the resources for the R/3 applications.
6. What are the functions of dispatcher?
Equal distribution of transaction load to the work processes.
Management of buffer areas in main memory.
Integration of the presentation levels.
Organization of communication activities.
7. What is a work process?
A work process is where individual dialog steps are actually processed and the work is done. Each work process handles one type of request.
8. Name various work processes of R/3 system?
Dialog or Online (processes only one request at a time).
Background (Started at a specific time)
Update (primary or secondary)
Enque (Lock mechanism).
Spool (generated online or during back ground processing for printing).
9. Explain about the two services that are used to deal with communication.
Message Service: Used by the application servers to exchange short internal messages, all system communications.
Gateway Service: Enables communication between R/3 and external applications using CPI-C protocol.
10. Which work process triggers database changes?
Update work process.
11. Define service (within R/3)?
A service is a process or group of processes that perform a specific system function and often provide an application-programming interface for other processes to call.
12. What are the roll and page areas?
Roll and page areas are SAP R/3 buffers used to store user contexts (process requests). The SAP dispatcher assigns process requests to work processes as they are queued in the roll and page areas.
Paging area holds data from the application programs.
Roll area holds data from previous dialog steps and data that characterize the user.
13. What are the different layers in R/3 system?
14. What are the phases of background processing?
15. What components of the R/e system initiate the start of background jobs at the specified time?
The batch scheduler initiates the start of background job. The dispatcher then sends this request to an available background work process for processing.
16. Define Instance.
An instance is an administrative unit in which components of an R/3 systems providing one or more services are grouped together. The services offered by an instance are started and stopped at random. All components are parameterized using a joint instance profile. A central R/3 system consists of a single instance in which all-necessary SAP services are offered. Each instance uses separate buffer areas.
17. From hardware perspective, every information system can be divided into three task areas Presentation, Application Logic and Data Storage.
The R/3 Basis software is highly suitable for use in multi-level client/server architectures.
18. What are R/3 Basis configurations?
A central system with centrally installed presentation software.
Two-level client/server system with rolled out presentation software.
Two-level client/server system. Presentation and Application run on the same computer.
Three-level client/server system. Presentation, Application and database each run on separate computers.
19. What is a Service in SAP terminology?
A service refers to something offered by a s/w component.
20. What is Server in SAP terminology?
A component can consist of one process or a group and is then called the server for the respective service.
21. What is a client in SAP terminology?
A S/W component that uses the service (offered by a s/w component) is called a Client. At the same time these clients may also be servers for other services.
22.What is a SAP system?
The union of all s/w components that are assigned to the same databases is called as a SAP system.
23. What is the means of communications between R/3 and external applications?
The means of communication between R/2,R/3 and external applications is via the CPI-C handler or SAP Gateway, using the CPI-C Protocol.
24. What is the protocol used by SAP Gateway process?
The SAP Gateway process communicates with the clients based on the TCP/IP Protocol.
25. Expand CPI-C.
Common Program Interface Communication.
26. What is a Spool request?
Spool requests are generated during dialog or background processing and placed in the spool database with information about the printer and print format. The actual data is places in the Tem Se (Temporary Sequential objects).
27. What are different types of Log records?
V1 and V2. V1 must be processed before V2. But, we can have more than one V2 logs.
28. What are the types of Update requests?
An update request can be divided into one primary (V1) and several Secondary update components (V2). Time-critical operations are placed in V1 component and those whose timing is less critical are placed in V2 components. If a V1 update fails, V2 components will not be processed.
29. Dialog work processes perform only one dialog step and then available for the next request.
30. Explain what is a transaction in SAP terminology.
In SAP terminology, a transaction is series of logically connected dialog steps.
31. Explain how SAP GUI handles output screen for the user.
The SAP front-end s/w can either run on the same computer or on different computers provided for that purpose. User terminal input is accepted by the SAP terminal program SAP GUI, converted to SAP proprietary format and sent to the SAP dispatcher. The dispatcher coordinates the information exchange between the SAP GUIs and the work processes. The dispatcher first places the processing request in request queues, which it then processes. The dispatcher dispatches the requests one after another, to the available work process. The actual processing takes place in the work process. When processing is complete, the result of a work process is returned via the dispatcher to the SAP GUI. The SAP GUI interprets the received data and generates the output screen for the user.