Software Engineering Chapter 2(2)

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 14

Software Engineering, 7th edition的英文课件作者Ian Sommerville

The system engineering process●

Usually follows a‘waterfall’ model because of the need for parallel development of different parts of the system Little scope for iteration between phases because hardware changes are very expensive. Software may have to compensate for hardware problems.

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Inevitably involves engineers from different disciplines who must work together Much scope for misunderstanding here. Different disciplines use a different vocabulary and much negotiation is required. Engineers may have personal agendas to fulfil.

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 15

Software Engineering, 7th edition的英文课件作者Ian Sommerville

The systems engineering process

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 16

Software Engineering, 7th edition的英文课件作者Ian Sommerville

Inter-disciplinary involvement

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 17

Software Engineering, 7th edition的英文课件作者Ian Sommerville

System requirements definition●

Three types of requirement defined at this stage Abstract functional requirements. System functions are defined in an abstract way; System properties. Non-functional requirements for the system in general are defined; Undesirable characteristics. Unacceptable system behaviour is specified.

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Should also define overall organisational objectives for the system.

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 18

Software Engineering, 7th edition的英文课件作者Ian Sommerville

System objectives●

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Should define why a system is being procured for a particular environment. Functional objectives To provide a fire and intruder alarm system for the building which will provide internal and external warning of fire or unauthorized intrusion. To ensure that the normal functioning of work carried out in the building is not seriously disrupted by events such as fire and unauthorized intrusion.

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Organisational objectives

©Ian Sommerville 2004

Software Engineering, 7th edition. Chapter 2

Slide 19