Requirements Engineering using Problem Frames Sample Clauses

Requirements Engineering using Problem Frames. A well-developed and structured requirements document which allows us to identify different abstraction levels is a key to successful formal modelling with a refinement-based method such as Event-B. Furthermore, the method used for requirements engineering shall provide means for handling large and complex systems by decomposing a problem into smaller parts and later recomposing these individual parts. Finally, it should support a semi- or pre- formal notation of requirements to make the step from informal requirements to a formal model manageable. We decided to use Problem Frames for this process and found the follow- ing strenghts and weaknesses: Strengths • Clear separation of requirements, environment, and system to be built • Supports elaboration and projection of the system into subproblems / different aspects • Supports a description of requirements at different levels of abstraction • Requirements are more precise than informal requirements Weaknesses • Sometimes requirements are still not as precise as needed for formal modelling • The refinement strategy in Problem Frames is not necessarily compat- ible with Event-B (see 5.3.5) • Separation of model information and requirements is not easy Still an open issue is the question how to specify non-functional require- ments like timing requirements. This should be addressed in the future.