ORM Levels

The ORM Levels are:

• Pure relational.
• Light objects mapping(jdbc).
• Medium object mapping.
• Full object mapping(composition,inheritance,polymorphismm,persistence by reachability)

Light Object Mapping:

The entities are represented as classes that are mapped manually to the relational tables. The code is hidden from the business logic using specific design patterns. This approach is successful for applications with a less number of entities, or applications with common, metadata-driven data models. This approach is most known to all.

Medium Object Mapping:

The application is designed around an object model. The SQL code is generated at build time. And the associations between objects are supported by the persistence mechanism, and queries are specified using an object-oriented expression language.

Full Object Mapping:

Full object mapping supports sophisticated object modeling: composition, inheritance, polymorphism and persistence. The persistence layer implements transparent persistence; persistent classes do not inherit any special base class or have to implement a special interface. Efficient fetching strategies and caching strategies are implemented transparently to the application.