The SAP Business Warehouse has different layers that are responsible for reliable data acquisition and information processing along with robust analytical capabilities. Based on the functions and applications in the solution, the different layers in SAP BW
The extraction layer is the collection of data from source systems. It aims to guarantee the integrity of data while eliminating reporting burdens on the source systems. Data can be extracted from an array of different sources. SAP NetWeaver BW offers predefined, customizable extractors for application data from the entire SAP Suite. You can also design extractors for customized SAP applications. Most extractors for SAP application transaction data are delta-enabled, which means that transactions can be written to a delta queue at the time of posting. They are then extracted from this delta queue into SAP BW.Direct extraction from databases based on table or view definitions using DB Connect and UD Connect extraction interfaces. DB Connect (Database Connection) permits the extraction from and direct access to data lying in tables or views of database management systems. This feature is available only for some specific databases. UD Connect (Universal Data Connect) permits the extraction from and direct access to both relational and multidimensional data. Web services allow you to push data to the SAP BW system with external control. Flat file interface enables extraction from flat files in ASCII and CSV format. Staging BAPIs (Staging Business Application Programming Interfaces) are open interfaces from which third-party tools can extract data from older systems. The data transfer can be triggered by a request from the SAP BW system or by a third-party tool. Data is acquired from SAP BW using a pull mode, through objects called InfoPackages. Parameters for the data acquisition can be set in the InfoPackage.
Extracted data is received and temporarily stored in the staging layer of SAP NetWeaver BW. The data staging layer stores source data from different operational sources. When data is inside of the staging layer all needed transformations can then occur without interfering with the operations in the source systems. Data is also preprocessed for cleansing before calculation and/or aggregation based on business requirements. This layer is mostly represented by the persistent staging area (PSA), where data is stored in SAP BW after it’s extracted. The technical structure of a PSA depends on the structure of the DataSource.
The transformation layer of SAP BW facilitates the consolidation, cleaning, and integration of data into the warehouse. Data gets converted from the source format into the desired destination data format. Data transformation can involve data mapping and formulas.
The actual process of pushing data through the transformation layer into the data targets. A data transformation process (DTP) transforms the data based on the parameters defined between the DataSource and the data target.
Reporting and Analysis layer
Within the reporting and analysis layer, reports and dashboards are created to display data in a format where analysis can be done. The components that represent the reporting and analysis layer are grouped together in the SAP business explorer (BEx) and more recently within Business Objects.