The basic idea of 1 is to introduce the theories and methods of software engineering and system engineering into the research and development of computer system, and analyze and design the system from top to bottom in a structured and modular way according to the principle of user first. Specifically, it divides the whole information system development process into six independent stages, including system analysis, program design, system testing, operation and maintenance, and system evaluation. These six stages constitute the life cycle of the information system.
2 Advantages and disadvantages
The outstanding advantage of life cycle method is that it emphasizes the integrity and overall situation of system development process, and considers specific analysis and design problems on the premise of overall optimization, that is, the top-down view. It divides software development and maintenance into several stages from the perspective of time, and each stage has its own relatively independent tasks and goals. It reduces the complexity of system development and improves the operability. In addition, the results of this stage are strictly examined and approved at each stage, and the problems are timely fed back and corrected, which ensures the quality of the software, especially improves the maintainability of the software. Practice has proved that the life cycle method greatly improves the success rate of software development.
However, the development cycle of life cycle method is long, because the development sequence is linear, it is impossible to carry out the work in each stage at the same time, and the mistakes made in the previous stage will inevitably be carried into the later stage, and the more mistakes made in the previous stage, the greater the impact on the later work, and the greater the workload spent on correcting mistakes. Moreover, in the case of frequent changes in functions, it is difficult to adapt to the changing needs and does not support repeated development.