软件开发设计外文翻译文献毕业论文.doc

外文资料原文 Software Development Concepts and Design Methodologies During the 1960s, mainframes and higher level programming languages were applied to many problems including human resource systems, reservation systems, and manufacturing systems. Computers and software were seen as the cure all for many business issues were sometimes applied blindly. Systems sometimes failed to solve the problem for which they were designed for many reasons including: ?Inability to sufficiently understand complex problems ?Not sufficiently taking into account end-user needs, the organizational environment, and performance tradeoffs ?Inability to accurately estimate development time and operational costs ?Lack of framework for consistent and regular customer communications At this time, the concept of structured programming, top-down design, stepwise refinement，and modularity emerged. Structured programming is still the most dominant approach to software engineering and is still evolving. These failures led to the concept of software engineering based upon the idea that an engineering-like discipline could be applied to software design and development. Software design is a process where the software designer applies techniques and principles to produce a conceptual model that describes and defines a solution to a problem. In the beginning, this design process has not been well structured and the model does not always accurately represent the problem of software development. However, design methodologies have been evolving to accommodate changes in technology coupled with our increased understanding of development processes. Whereas early design methods addressed specific aspects of the development process, current methods attempt to address the entire scope of software development. Software design methods are often classified in reference to the period in which they were introduced and the problems at that time. Driven by coding and testing problems, tools and methods were developed.