软件工程：Computer-Based System Engineering.pptVIP

Chapter 2 Computer-Based System Engineering Systems Engineering Designing, implementing, deploying and operating systems which include hardware, software and people Objectives To explain why system software is affected by broader system engineering issues To introduce the concept of emergent system properties such as reliability and security To explain why the systems environment must be considered in the system design process To explain system engineering and system procurement processes Topics covered Emergent system properties Systems and their environment System modelling The system engineering process System procurement What is a system? A purposeful collection of inter-related components working together towards some common objective. A system may include software, mechanical, electrical and electronic hardware and be operated by people. System components are dependent on other system components The properties and behaviour of system components are inextricably inter-mingled Problems of systems engineering Large systems are usually designed to solve wicked problems Systems engineering requires a great deal of co-ordination across disciplines Almost infinite possibilities for design trade-offs across components Mutual distrust and lack of understanding across engineering disciplines Systems must be designed to last many years in a changing environment Software and systems engineering The proportion of software in systems is increasing. Software-driven general purpose electronics is replacing special-purpose systems Problems of systems engineering are similar to problems of software engineering Software is (unfortunately) seen as a problem in systems engineering. Many large system projects have been delayed because of software problems Emergent properties Properties of the system as a whole rather than properties that can be derived from the properties of components of a system Emergent properties are a consequence of the relationships between system c