Report Models and the Model Designer

As previously mentioned, the first step in creating end- user reports is the creation of the report model. The model is written in a declarative language called Semantic Definition Model Language (SDML). The Semantic Definition Model Language is based on the Unified Modeling Language (UML), and it contains many of the same paradigms . It is similar to the RDL in that it is an XML-based communications language. The report model abstracts the RDBMS into business objects the end user would recognize.

To be effective for the end user, the model author must include some key pieces of information about the database. This type of information includes the following:

• A map of table names and column names into business objects

• Information about the relationships between tables that would otherwise be stored in primary keys or foreign keys

• Hierarchical information or logical groupings about your objects

• Permissions for users to see objects

From Report Builder, the model aids the user in selecting what information she wants to see, and, consequently, building the query for the data source of the resulting report.

To build these models, model developers must use a tool called Model Designer. Like Report Designer, it is built in to Visual Studio/Business Intelligence Development Studio. The template project type is called "Report Model Project." Models can be generated against SQL Server or Analysis Services

Note

Model Designer and, subsequently, Report Builder can only build reports against SQL Server or Analysis Services. To build reports for other data sources, such as Oracle, you can employ linked servers or the unified data model (UDM). Both provide a thin abstraction layer.

Developers can generate models in two ways. The first way to generate models is based on a set of preexisting rules. This is the way the wizard and the autogenerate functionality work. The other way is to connect using a data source, and start designing the model by hand.

You will take a look at both methods later in this chapter.