Information models describe the conceptual view of the information and the link to the physical representation by a multilayer structure.
Metasafe implements an "executable conceptual model": it manages the models (conceptual and external) and also the structurally equivalent instance data.
- The conceptual schema describes semantic model of a domain or even of an enterprise.
The entity-relationship model is the (de facto) standard representation of conceptual schemas and external schemas.
- External schemas describe the user views as a subset of the conceptual schema.
- The internal schema (aka logical model) describes the view exposed by the underlying DBMS (i.e. the access services offered by the DBMS). Structural differences between the conceptual model (i.e. the ER-Model) and the logical model (i.e. DBMS) require a mapping and transformation.