Towards the Harmonisation of UML and SDL

UML and SDL are languages for the development of software systems that have different origins, and have evolved separately for many years. Recently, it can be observed that OMG and ITU, the standardisation bodies responsible for UML and SDL, respectively, are making efforts to harmonise these languages. So far, harmonisation takes place mainly on a conceptual level, by extending and aligning the set of language concepts. In this paper, we argue that harmonisation of languages can be approached both from a syntactic and semantic perspective. We show how a common basis can be derived from the analysis of the UML meta-model and the SDL abstract grammar. For this purpose, conceptually sound and well-founded mappings from meta-models to abstract grammars and vice versa are defined and applied. The long term objective is the syntactic and semantic integration of UML and SDL. The key to achieving this objective is a common language core, which can then be extended in different ways to cover further, more specific language concepts, and is sufficiently flexible to support future language add-ins.