Development of requirements specifications is a key activity in the development of a system. Errors in a requirements specification
can cost orders of magnitude more to detect and fix than errors in the implementation. Model based development techniques
can help validation of requirements specifications by allowing early simulation and testing. However models are created by
interpreting written requirements, and potential representation errors continue to exist.
This paper reports on ‘AMBERS’, or Assertive Model-Based Engineering Requirement Specifications, an Airbus initiative to improve
the quality of engineering specifications by providing a common framework for requirements engineers and modelling engineers
to work in. The AMBERS framework builds on the Software Cost Reduction US-NRL method to augment textual requirements with
assertive (Parnas) function tables and creates a bridge to model-based developments by using these tables as proof objectives
that a model must comply with. This supports proof-guided simulation and testing, allowing more effective use of validation
activities.
Extending DOORS and SCADE to provide a two-way traceability between model and requirements specification, and to provide support
for automatic proof generation has allowed developing a tool support prototype for the ‘AMBERS’ approach.