Object role modeling

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The designer of a database builds a formal model of the application area or universe of discourse (UoD). The model requires a good understanding of the UoD and a means of specifying this understanding in a clear, unambiguous way. Object-Role Modeling (ORM) simplifies the design process by using natural language, as well as intuitive diagrams which can be populated with examples, and by examining the information in terms of simple or elementary facts. By expressing the model in terms of natural concepts, like objects and roles, it provides a conceptual approach to modeling. Its attribute-free approach promotes semantic stability.

ORM evolved from the Natural language Information Analysis Method (NIAM, also known as aN Information Analysis Method) and Binary Relationship Modeling, which were developed in Europe in the mid-1970s. Dr. Terry Halpin provided the first formalization of Object-Role Modeling.

ORM's rich graphic notation is capable of capturing many business rules that are typically unsupported as graphic primitives in other popular data modeling notations.

Various software tools exist to enter ORM schemas, and generate relational database schemas. These include Microsoft Visio for Enterprise Architects, CaseTalk, Infagon, and NORMA.

NORMA (Neumont ORM Architect), an open source plug-in to Microsoft Visual Studio 2005, supports ORM 2 (second generation ORM), and maps ORM schemas to a variety of implementation targets, including relational DBMSs, object-oriented code, and XML schema. As of April 2006, NORMA (accessible at the SourceForge link [1] below) is in a prototype stage, but is evolving to a full production version.

A graphical NIAM design tool which included the ability to generate database-creation scripts for Oracle, DB2 and DBQ was developed in the early 1990's in Paris. It was originally named Genesys and was marketed successfully in France and later Canada. It could also handle ER diagram design. It was ported to SCO Unix, SunOs, DEC 3151's and Windows 3.0 platforms, and was later migrated to succeeding Microsoft operating systems, utilising XVT for cross operating system graphical portability.

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The Dutch successor of NIAM is continuously researched and developed and is called FCO-IM. The case tool of choice implementing this is called Casetalk. FCO-IM has some advantages for it considers only facts.