SAP BW is based on integrated metadata concept with metadata being managed by metadata services. SAP's BW has following layers
Extraction, Loading and Transformation (ELT) services layer.
Storage services layer, with services for storing and archiving information.
Analysis and access services layer, which provides access to the information stored in SAP BW.
Presentation services layer, which offers different options for presenting information to end users.
Administration services.
Metadata services
