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SAP R/3 Extraction and BW Overview

The transaction data entering the Business Information Warehouse by means of extractors originates from very different modules. Due to past developments, very different extraction mechanisms are necessary.Before you start an SAP BW project (and also if BW is already in productive use), you will probably think about the reports you want to run and the data you need from the R/3 System.You will then have to take a look at the sources shipped with SAP Business Content to decide which ones meet your requirements and can be used by default.If you need data that cannot be supplied by the standard sources, you can: 

Create new InfoSources
Enhance the standard ones

As components of the Business Framework, OLTP applications and the Business Information Warehouse communicate via BAPIs (Business Application Programming Interfaces).The extraction mechanisms that are used to prepare the production data in each application for the Business Information Warehouse are located in an R/3 OLTP System. The purpose of this course is to explain how these extraction mechanisms in the R/3 OLTP System work.With non-SAP applications, the prerequisites for exchanging data between the application and the Business Information Warehouse can be met by separate installations from external suppliers.

 
 Extracting Transaction Data

A DataSource describes a type of infrastructure that allows information to be transported between OLTP Systems and BW. This infrastructure comprises various DDIC structures that are linked by means of transformation rules. DataSources, therefore, regula te the flow of data between the extraction source structure in the source system to the communication structure in BW, via which the respective data is supplied. DataSources can supply both transaction data (stored in InfoCubes) and master data (attributes, texts, and hierarchies - stored in separate, transparent tables). The structure of the DataSources for transaction and master data is almost identical.

DataSources describe the set of all available data for a business event, or type of business event (for example, Cost Center Accounting). For this reason, every operative SAP BW environment will contain a large number of DataSources that describe the individual operations within the applications that are to be analyzed.

Each time a DataSource is generated, the corresponding transfer and communication structures are also generated in the BW System. Transfer structures always exist in pairs - in a source system and in the associated SAP BW System. This transfer structure is used to transfer data in the format of the original application from a source system to BW, where it is forwarded to the communication structure of the InfoSource using transformation rules.The communication structure is independent of the source system and contains all of the fields in the InfoSource that it represents in BW.


Extracting Master Data

A DataSource describes a type of infrastructure that allows information to be transported between OLTP Systems and BW. This infrastructure comprises various DDIC structures that are linked by means of transformation rules. DataSources, therefore, regulate the flow of data between the extraction source structure in the source system to the communication structure in BW, via which the respective data is supplied. DataSources can supply both transaction data (stored in InfoCubes) and master data (attributes, texts, and hierarchies - stored in separate, transparent tables). The structure of the DataSources for transaction and master data is almost identical.

DataSources describe the set of all available data for a business event, or type of business event (for example, Cost Center Accounting). For this reason, every operative SAP BW environment will contain a large number of DataSources that describe the individual operations within the applications that are to be analyzed.

Each time a DataSource is generated, the corresponding transfer and communication structures are also generated in the BW System. Transfer structures always exist in pairs - in a source system and in the associated SAP BW System. This transfer structure is used to transfer data in the format of the original application from a source system to BW, where it is forwarded to the communication structure of the InfoSource using transformation rules.The communication structure is independent of the source system and contains all of the fields in the InfoSource that it represents in BW.


Info Sources in the R/3 OLTP System

Every DataSource gets its data in some form from transparent tables in the R/3 OLTP System. The database of such an extractor is therefore a transparent table.The extractor now defines by which methods data will be extracted. Extraction can now take place directly from the transparent table. It can also take place with a database overview, a function module or SAP Query. This means you can use a view to go to several different database tables. n The extractor forwards the data to the extract structure. The extractor may be able to supply data to more fields than exist in the extract structure. But it may also be the case that the extract structure has more fields than the extractor can supply to. These fields can then be supplied with data using function enhancements (see unit on Enhancing Business Content).

Data elements of the respective SAP OLTP Data Dictionary describe the individual fields of the extract structure. For SAP BW, we also need a description of InfoObjects in the SAP BW Metadata Repository.The fields in the extract structure must then be assigned InfoObjects. Not all the fields in the extract structure have to be assigned InfoObjects. However, after a Metadata upload, only the fiields that were assigned an InfoObject are made available in the template DataSource for creating the communication structure.





Effects of Subsequent Activities in SAP BW

Once a DataSource has been generated in the OLTP system, the Metadata must be uploaded to the SAP BW System. During this process, a template DataSource for selecting the fields in the communication structure is created from the InfoObjects assigned to the extract structure.The fields in the communication structure then have to be supplied with data by means of transfer rules. This can take place using a field in the template DataSource, a fixed value, or a function exit. The fields in the template DataSource that are used to populate the communication structure together define the transfer structure.The transfer structure is generated automatically when the transfer rules are activated in SAP BW and in the R/3 OLTP System.

Replicating DataSources
 
The DataSource is replicated in BW.
Fields in the OLTP extract structure that have been assigned
InfoObjects are made available in a template DataSource in BW.
Assigning InfoSources
The DataSource is assigned to an InfoSource.
Maintaining the Communication Structure
The communication structure is generated from the selected fields in the template InfoSource in BW.
Creating Transfer Rules
The transfer structure is generated from the selected
InfoObjects in the template DataSource in BW and in the R/3 OLTP System.

Business Content Extractors

SAP provides extractors for almost all applications.These extractors are programmed on a fixed basis and shipped with Business Content. However, some Business Conent extractors do use the technology of the cross-application generic extrractors.Business Content is developed and enhanced with every new BW Release.




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