Real-time structured analysis and object-oriented design: a pragmatic approach for flight simulation

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Real-time structured analysis and object-oriented design: a pragmatic approach for flight simulation

Weaver, C.

Object-oriented design (OOD) has received much attention, more so than that given to object-oriented analysis (OOA). Techniques for OOA are still emerging and lack strong CASE tool support. In order to improve upon this situation, this paper presents work taking a 'traditional' structured analysis and demonstrates the mapping of this into an object-oriented design. Structured analysis is well-known, proven and easily understood by staff with average engineering skills. The strategy employed is not based on information modelling since this is the least well practised of the viewpoints in structured analysis. The use of structured analysis achieves the rigour in understanding and presenting the system requirements, whilst object-oriented design results in clearer, more maintainable code that reflects the real-world structure of the problem. An example is given, using the problem of simulating a turbofan engine. The approach is pragmatic, in that the prime benefit of object-orientation is seen as minimising the impact of change by controlling scope and visibility. This was done by grouping to minimise interfaces between objects in the analysis and organizing the software architecture to maximise information hiding. Reuse, in the form of inheritance, was unavailable in Ada, the chosen implementation language. This proved to be a problem as the example application could have been more neatly expressed using this technique. However, with CASE tool support for the requirements analysis phase, it was possible to generate large portions of the resultant code.