1.3 BWAn SAP Data Warehousing Solution

1.3 BW—An SAP Data Warehousing Solution

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 :

   • BEx Analyzer

   • 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 :

   • Administering the BW system

   • Storing data

   • 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:

   • Administrator Workbench, including BW Scheduler and BW Monitor

   • Metadata Repository and Metadata Manager

   • Staging Engine

   • PSA (Persistent Staging Area)

   • ODS (Operational Data Store) Objects

   • InfoCubes

   • Data Manager

   • OLAP Processor

   • BDS (Business Document Services)

   • User Roles

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 BW Scheduler, 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.

Table 1.5 indicates where each of these components is discussed in this book. As noted in the Preface, this book does not discuss third-party reporting tools and BAPI.

Table 1.5. CHAPTERS DETAILING BW COMPONENTS