A generic framework for transforming EXPRESS information models

The ability to share information on an enterprise-wide basis is a key requirement for large manufacturing and processing industries such as automotive, aerospace and oil processing companies. The Standard for the Exchange of Product Model data (STEP-ISO 10303) addresses this through formats and programming interfaces derived directly from domain-related information models written in the EXPRESS information modelling language. However, these formats and programming interfaces are predetermined, and not always well suited to current information processing technologies. In this paper, a framework for manipulating EXPRESS models is described. The goal is to retain the STEP concept of the direct mapping of an information model to an implementation, but to do so in a way that enables alternative implementation strategies to be adopted. This system, called STEPWISE, allows the user to specify manipulations and model transformations in order to convert models from one form into another. This might, for example, involve conversion from a conceptual model to an implementation-level data model, creating a subset of a model, or even adding concepts to a low-level model that represents a legacy data format. The transformations are carried out on the models in such a way that the integrity of the referencing and the constraints can be maintained as far as possible. Various examples of model manipulation are described in order to illustrate the issues that must be considered when manipulating sophisticated conceptual models.