O RM i n Dynamic L anguages

A major component of most enterprise applications is the code that transfers objects in and out of a relational database. The easiest solution is often to use an ORM (object-relational mapping) framework, which allows the developer to declaratively define the mapping between the object model and database schema and express database-access operations in terms of objects. This high-level approach significantly reduces the amount of database-access code that needs to be written and boosts developer productivity.

Several ORM frameworks are in use today. For example, the Hibernate, ¹ TopLink, ² and OpenJPA³ frameworks are popular with Java developers, and NHibernate⁴ is used by many .NET developers. Two newer ORM frameworks that have recently received a lot of attention from enterprise developers are Active Record⁵ for Ruby⁶ and GORM (Grails Object Relational Mapping) ⁷ for Groovy. ⁸ These new frameworks differ from traditional ORM frameworks in that they are written in dynamic languages that allow new program elements to be created at runtime. Active Record and GORM use these dynamic capabilities in ways that can significantly simplify an application.