Chapter 9 Working with Object-Oriented Models

Mapping objects in an OOM

Developers tend to use object-oriented programming languages like Java, to develop business objects and components. These objects can be stored in a database. A problem arises when the user tries to store objects in a relational database because object modeling describes a system through objects that have identity, behavior and encapsulated state whereas relational modeling describes a system by its data.

Furthermore, object codes in an OOM for a given object language are often different than codes used in a relational database. This requires that you modify object codes after generating an OOM into a PDM or a PDM into an OOM to be compliant with the object language.

You can use object mapping to bypass this impedance-mismatch.

Object mapping is the ability to establish a correspondence between objects belonging to heterogeneous models and diagrams. In an OOM, you can link classes to tables in a PDM, this process is called object to relational mapping (O/R mapping).

O/R mapping allows to manage the persistence of objects in a relational database.