需求分析和系统设计_摘需求分析和系统设计_摘要.pptVIP

Topics The nature of software development System planning Systems for three management levels Software development lifecycle The essence of software development Only one out of three software projects complete on-time and on-budget (The Standish Group report, 2003) The essence of software development: defined by the issues inherent in the software itself -software is a product of a creative act (not a result of a repetitive act of manufacturing) difficulties not amenable to breakthroughs or ‘silver bullets’ - define software development invariants consequence of the inherent software complexity, complexity, conformity, conformity, changeability, and changeability, and invisibility The accidents of software development ‘Accidental difficulties’ due to software production practices - amenable to human intervention attributed mostly to the fact that an information system is a social system must not be adding to the complexity and to the potential lack of supportability of the software product supportability = understandability + maintainability +scalability (extensibility) Related to: Stakeholders Process Modeling language and tools Will be discussed soon Software development invariants Software in inherently complex ? function of interdependencies between components of which the software product is composed ? complexity in the wires ? Data intensive applications (enterprise information systems) are particularly complex Software must conform to: ? hardware/software platform on which it is built ? pre-existing information systems Software must be built to accommodate change Software is buried deeply in “invisible” programming statements, binary library code, and surrounding system software Stakeholders People who have a stake in a software project: Customers (users and system owners) Developers (analysts, designers, programmers, etc.) Information systems are social systems -developed by people (developers) for people (customers) The main causes of software fa