Modeling of Natural Language Requirements based on States and Modes

The relationship between states (status of a system) and modes (capabilities of a system) used to describe system requirements is often poorly defined. The unclear relationship could make systems of interest out of control because of the out of boundaries of the systems caused by the newly added modes. Formally modeling requirements can clarify the relationship between states and modes, making the system safe.To this end, the MoSt language (a Domain Specific Language implemented on the Xtext framework) is proposed to modeling requirements based on states and modes. In this article, the relationship between states and modes is firstly provided. The metamodel and grammar of the language are then proposed. Finally, a validator is implemented to realise static checks of the MoSt model. The grammar and the validator are integrated into a publicly available Eclipse-based tool. A case study on requirements for designing cars has been conducted to illustrate the feasibility of the MoSt language. In this case study, we injected 9 errors. The results show that all the errors were detected in the static analysis.