The Presentation layer provides a way to present customized views of a business model to users. Presentation Catalogs in the Presentation layer (called Subject Area in Oracle Answers) are seen as business models by Oracle BI Presentation Services users. They appear as catalogs to client tools that use the Oracle BI Server as an ODBC data source. The following topics describe the Process of creating the Presentation layer.
NOTE: In offline editing, remember to save your repository from time to time. You can save a repository in offline mode even though the business models may be inconsistent.
There are several ways to create a Presentation Catalog in the Presentation layer. The recommended method is to drag and drop a business model from the Business Model and Mapping layer to the Presentation layer, and then modify the Presentation layer based on what you want users to see. You can move columns between presentation tables, remove columns that do not need to be seen by the users, or even present all of the data in a single presentation table. You can create presentation tables to organize and categorize measures in a way that makes sense to your users.
One important reason to use a custom Presentation layer is to make the schema as easy to use and understand as possible. Therefore, users should not be able to view columns that have no meaning to them. The following columns are examples of columns that you might want to remove from the Presentation layer:
- Key columns that have no business meaning.
- Columns that users do not need to view (for example, codes, when text descriptions exist).
- Columns that users are not authorized to see.
NOTE: You can also restrict access to tables or columns in the security layer. For more information, refer to Security in Oracle BI.
By default, presentation columns have the same name as the corresponding logical column in the Business Model and Mapping layer. However, you can specify a different name to be shown to users by changing the name in the Presentation Column dialog box. Whenever you change the name of a presentation column, an alias is automatically created for the old name, so compatibility to the old name remains.
For each presentation catalog in the Presentation layer, decide whether to export any logical keys as key columns to tools that access it in the Presentation Catalog dialog box. Exporting logical keys is irrelevant to users of Oracle BI Presentation Services, but it may be advantageous for some query and reporting tools. If you decide to export logical keys, be sure the logical key columns exist in the table folders. In this situation, your business model should use logical key/foreign key joins.
When you select the option Export logical keys in the Presentation Catalog dialog box, any columns in the Presentation layer that are key columns in the Business Model and Mapping layer are listed as key columns to any ODBC client. This is the default selection. In most situations, this option should be selected.