Enterprise information systems: specifying the links among project data models using category theory

Major enterprise information systems are frequently specified by integrating information models which have been developed in separate divisions of the enterprise. These models, often called project data models, embody the information that needs to be modelled in the enterprise, but they can be difficult to link because when common information is stored in different divisions it is frequently stored in significantly different forms. This paper describes a new technique, based on category theory, that uses the specification of logically data independent views to link project data models. The link mechanism is powerful because the use of views permits data in radically different forms to be linked, and a new solution to the view update problem allows the linking mechanism to be embodied as code, thus allowing the linked data models to be implemented as interoperating information systems. The paper is somewhat theoretical since it describes the foundation for a new technique, but the methods described here are being tested in large consultancies including the enterprise models for a government department, an oil company, and a telecommunications carrier.