Active database support for STEP/EXPRESS models

The ISO STEP specifications aim to provide an effective means through which product information can be shared and exchanged between applications and enterprises. EXPRESS is a modelling language within the STEP specifications, which is used to describe product data. An EXPRESS model can be implemented on a database repository, queried upon and manipulated. However, EXPRESS models capture only the static aspects of a system. In this paper, proposed extensions to the EXPRESS language are made in order to model the dynamic behaviour of products and processes. A translator is implemented to transform such models to an active database, which has been developed on an object-oriented database, ObjectStore. The active component of the system is based on CLIPS, an expert system. Throughout the paper, a case based on a workflow process is used to demonstrate how a model can be mapped onto an active database.