Abstract
Model-driven Architecture (MDA) is a software architecture framework proposed by the Object Management Group OMG. MDA emphasises the importance of modelling in the architectural design of service-based software systems, Ontologies call enhance the modelling aspects here. We present ontology-based transformation and reasoning techniques for a layered, MDA-based modelling approach, Different ontological frameworks shall support domain modelling, architectural modelling and interoperability. Ontologies are beneficial due to their potential to formally define and automate transformations and to allow reasoning about models at all stages. Ontologies are suitable in particular for the Web Services platform due to their ubiquity within the Semantic Web and their application to support semantic Web services.