VDM (Virtual Data Model) forms the basis of data access in S4 HANA APIs and Analytical Applications which is represented by the CDS views. The CDS views expose the data stored in the DB tables in a format of business semantics which therefore is easy to consume.
VDM Layers and View Types-
In VDM, the VDS views can be differentiated according to their position in the VDM layer, their purpose and their intended reuse.
The VDM views are build on top of the DB tables which makes the data easy to consume. The consumption layer consists of consumption views where as the reuse view layer consists of basic and composite views.
Basic Interface Views are just above the DB tables and are the only views that access the access the DB table directly. The annotation: @VDM.viewType: #BASIC
Composite Interface Views are based on the basic interface views and may also have associations to other composite views. They don’t access the data from DB table directly but via the basic views. It can combine multiple basic interface views or other composite views. The annotation: @VDM.viewType: #COMPOSITE
Consumptions Views is the top layer view of the VDM view stack. They are based on reuse views and access the DB table indirectly through the reuse view layer. These views are designed for a specific requirement and purpose. Consumption views are the only vdm view type that can function as a analytic query. The annotation: @VDM.viewType: #CONSUMPTION