What is the Presentation Layer?

The presentation layer provides users with customized, secure, role-based views of a business model.

Role-based views provide object security and also provide a way to hide some of the complexity of the business model.

In the presentation layer, you can set an implicit fact column. The primary function of the presentation layer is to provide custom names, dictionary entries, organization, and security for different groups of users.

Presentation layer views are called subject areas. Subject areas contain presentation tables, columns, hierarchies, and levels. You can create a subject area that's identical to your business model, or you can create role-based subject areas that show a single subject or that supports a specific business role. Subject areas aren't abstract views. You should create subject areas that organize your content in a way that benefits your users.

You can use a JDBC connection to query subject areas externally. When you access subject areas in this way, the subject areas are displayed as catalogs.

Even though the Logical SQL requests from visualizations, analyses, and other clients query the presentation tables and columns, the logic for entities, relationships, and joins is in the logical layer.

There is no automatic way to synchronize all changes between the logical layer and the presentation layer. For example, if you add logical columns to an existing logical table, or edit existing columns, you must manually update the corresponding presentation layer table and columns.

In some cases, if there are many changes to a logical table or even to an entire business model, it's easiest to delete the corresponding presentation table or subject area, and then and drag and drop the updated logical objects to the presentation layer. For this reason, it's best to wait until the logical layer is relatively stable before adding customizations in the presentation layer.