Requirements and design
l In principle, requirements should state what the system should do and the design should describe how it does this l In practice, requirements and design are inseparable • A system architecture may be designed to structure the requirements • The system may inter-operate with other systems that generate design requirements • The use of a specific design may be a domain requirement
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 5 Slide 37
Problems with NL specification
l Ambiguity • The readers and writers of the requirement must interpret the same words in the same way. NL is naturally ambiguous so this is very difficult l Over-flexibility • The same thing may be said in a number of different ways in the specification l Lack of modularisation • NL structures are inadequate to structure system requirements