ETL service comprises of two
parts: Staging engine and Storage Service. Staging engine manages staging
process for all data received from several source systems. It interfaces
with the AWB scheduler and monitor for scheduling and monitoring data load
processes. However, Storage Service manages and provides access to data
targets in SAP BW and the aggregates that are stored in relational and
multidimensional database management systems.
It is true, however, that the
extraction technology provided as an integral part of SAP BW is restricted
to database management systems supported by mySAP technology and that it
does not allow extracting data from other database systems like IBM IMS and
Sybase. It also does not support proprietary file formats such as dBase file
formats, Microsoft Access file formats, Microsoft Excel file formats, and
others. On the other hand, the ETL services layer of SAP BW provides all the
functionality required to load data from non-SAP systems in exactly the same
way as it does for data from SAP systems. SAP BW does not in fact
distinguish between different types of source systems after data has arrived
in the staging area. The ETL services layer provides open interfaces for
loading non-SAP data.
Extraction at
Service Levels
SAP BW can be integrated with
other SAP components based on application programming interface (API)
service. It provides a framework to enable comprehensive data replication
based on data extractors that encapsulate the application logic. Data
Extractor fills the extract structure of data source with a data from data
source and offers sophisticated handling of changes. In addition to
supporting extractors, the service APIs also enable online access via
RemoteCube technology and flexible staging for hierarchies. On the other
hand SAP provides an open interface called Staging Business Application
Programming Interface (BAPI) to extract data from non-SAP sources. BAPI
serves the purpose of connecting third- party ETL tools to SAP BW and
provides access to SAP BW objects which facilitates use of customer
extraction routines. Data can be extracted at the database level by using:
DB connect, flat files and XML. DB connect facilitates extraction directly
from DBMS. In this the metadata files are loaded by replicating metadata
tables and views into the metadatory repository of SAP BW. Data can also be
uploaded from flat files by creating routines for extraction of data and XML
files can be extracted through XML via Administrator Workbench in SAP BW.
NOTE: SAP BW
provides three ways to extract data at the database or file level: DB
Connect, flat file transfer, and XML. SAP BW provides flexible capabilities
for extracting data directly from RDBMS tables using DB Connect.
