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2.1.1.1 Unified Dimensional Model

The Analysis Services metadata model, called a Unified Dimensional Model (UDM), provides a bridge between users and the data sources. A UDM is constructed over one or more physical data sources, and it allows end-user queries using one of a variety of client tools, such as Microsoft Office Excel.

Unified Dimensional Model

Figure 1: Unified Dimensional Model

A UDM contains information about:

  • Data source connections.

  • A schema snapshot for data that exists in a data source.

  • The user-visible concepts, such as dimensions, hierarchies, and key performance indicators.

  • Mapping between the user-visible concepts and the underlying data sources.

  • Calculations that encapsulate business logic, such as a three-month moving average.

  • Security roles and associated authorizations.

For more information about the UDM, see [MSDN-UDM].

A UDM is typically defined by IT professionals using Business Intelligence Development Studio. During the development process, UDM metadata is stored in proprietary XML-based files. Once this UDM definition is complete, it can be deployed by Business Intelligence Development Studio to an analysis server by using the SQL Server Analysis Services Protocol [MS-SSAS] where it is stored in a proprietary format. For more information about Business Intelligence Development Studio, see [MSDN-BIDS].