BW is an end-to-end data warehousing solution that uses preexisting SAP technologies.
BW is built on the Basis 3-tier architecture and coded in the ABAP (Advanced Business
Application Programming) language. It uses ALE (Application Link Enabling) and BAPI
(Business Application Programming Interface) to link BW with SAP systems and non-
SAP systems.
1.3.1 BW Architecture
Figure 1.3 shows the BW architecture at the highest level. This architecture has three
layers:
1. The top layer is the reporting environment. It can be BW Business Explorer
(BEx) or a third-party reporting tool. BEx consists of two components:
o BEx Analyzer
o BEx Browser
BEx Analyzer is Microsoft Excel with a BW add-in. Thanks to its easy-to-use
graphical interface, it allows users to create queries without coding SQL
statements. BEx Browser works much like an information center, allowing users
to organize and access all kinds of information. Third-party reporting tools
connect with BW OLAP Processor through ODBO (OLE DB for OLAP).
2. The middle layer, BW Server, carries out three tasks:
o Administering the BW system
o Storing data
o Retrieving data according to users' requests
We will detail BW Server's components next.
3. The bottom layer consists of source systems, which can be R/3 systems, BW
systems, flat files, and other systems. If the source systems are SAP systems, an
SAP component called Plug-In must be installed in the source systems. The Plug-
In contains extractors. An extractor is a set of ABAP programs, database tables,
and other objects that BW uses to extract data from the SAP systems. BW
connects with SAP systems (R/3 or BW) and flat files via ALE; it connects with
non-SAP systems via BAPI.
The middle-layer BW Server consists of the following components:
o Administrator Workbench, including BW Scheduler and BW Monitor
o Metadata Repository and Metadata Manager
o Staging Engine
o PSA (Persistent Staging Area)
o ODS (Operational Data Store) Objects
o InfoCubes
o Data Manager
o OLAP Processor
o BDS (Business Document Services)
o User Roles
Figure 1.3. BW ARCHITECTURE
Administrator Workbench maintains meta-data and all BW objects. It has two
components:
• BW Scheduler for scheduling jobs to load data
• BW Monitor for monitoring the status of data loads
This book mainly focuses on Administrator Workbench.
Metadata Repository contains information about the data warehouse. Meta-data
comprise data about data. Metadata Repository contains two types of meta-data:
business-related (for example, definitions and descriptions used for reporting) and
technical (for example, structure and mapping rules used for data extraction and
transformation). We use Metadata Manager to maintain Metadata Repository.
Staging Engine implements data mapping and transformation.
Triggered by BWScheduler, it sends requests to a source system for data loading.
The source system then selects and transfers data into BW.
PSA (Persistent Staging Area) stores data in the original format while being imported
from the source system. PSA allows for quality check before the data are loaded into their
destinations, such as ODS Objects or InfoCubes.
ODS (Operational Data Store) Objects allow us to build a multilayer structure for
operational data reporting. They are not based on the star schema and are used primarily
for detail reporting, rather than for dimensional analysis.
InfoCubes are the fact tables and their associated dimension tables in a star schema.
Data Manager maintains data in ODS Objects and InfoCubes and tells the OLAP
Processor what data are available for reporting.
OLAP Processor is the analytical processing engine. It retrieves data from the database,
and it analyzes and presents those data according to users' requests.
BDS (Business Document Services) stores documents. The documents can appear in
various formats, such as Microsoft Word, Excel, PowerPoint, PDF, and HTML. BEx
Analyzer saves query results, or MS Excel files, as workbooks in the BDS.
User Roles are a concept used in SAP authorization management. BW organizes BDS
documents according to User Roles. Only users assigned to a particular User Role can
access the documents associated with that User Role.
