Supporting Reuse in Event B Development: Modularisation Approach

Recently, Space Systems Finland has undertaken formal Event B development of a part of the on-board software for the BepiColombo space mission. As a result, lack of modularisation mechanisms in Event B has been identified as a serious obstacle to scalability. One of the main benefits of modularisation is that it allows us to decompose system models into components that can be independently developed. It also helps to manage complexity of models that in the industrial setting are usually very large and difficult to comprehend. On the other hand, modularisation enables reuse of formally developed components in the formal product line development. In this paper we propose a conservative extension of Event B formalism to support modularisation. We demonstrate how our approach can support reuse in the formal development in the space domain.