Database modelling is classically defining the database dictionary, database structuring and functionality within one singleton paradigm. This approach has led to sophisticated financial services, to enterprise information systems and other database-backed practical solution which are easy to handle, relatively simple to change and to implement and which satisfied the needs of business in the 90ies. At the same time a number of applications have been developed that used the potential within the data for analysis, for exchange and collaboration of systems, e.g. OLTP-OLAP systems, decision support systems, scientific information systems, collaborative information systems and web information systems. These applications do not use a singleton language for data storage, data computation and data delivery. Their languages use different paradigms. We therefore need a way for specification of database applications that provide facilities for appropriate modelling depending on the needs.

This paper aims in developing a framework for modelling and implementing layered database applications. It defines a database model for each of the layers and a facility for exchange of data throughout the different layers in a coherent form.