one , Waterfall model ：
1, thought ： From the production time according to the process to simplify the problem
The function realization and production are separated to facilitate division of labor and cooperation
2, characteristic ：
The sequence and dependence between stages are very strong
qa , Deliver qualified documents at each stage , And audit the documents
The idea of postponement
3, advantage ：
The foundation of software method is established
Water dependence , Facilitate division of labor and cooperation
Postpone physical implementation , Easy to modify document , With quality assurance
4, shortcoming ： Target system meets users late , The later the problem is discovered , The higher the cost of modification , Low success rate , In general 25%
5, Scope of application ：
It is suitable for systems with clear system requirements
All kinds of application software development can be used
two , Rapid prototyping model
1. advantage ：
Overcome the shortcomings of waterfall model , Better meet the needs of users and reduce the risk of project development due to unclear software requirements .
It is suitable for the development of software system which can't define the requirement in advance .
2. shortcoming ：
It is not suitable for the development of large-scale system （ Suitable for the development of small , Flexible system ）.
The premise is to have a demonstrative product prototype , Therefore, to a certain extent, it may limit the innovation of developers .
three , Evolution model
Because in the initial stage of project development, people's understanding of software requirements is often not clear enough , Therefore, it is difficult to achieve a successful software development, rework is inevitable , The first time was just in experimental development , Explore the feasibility in the first time , Understand the software requirements , On this basis, the second time （ Limited development ） Make a satisfied product
four , incremental model
1. thought ： Starting from the part , First, build an incomplete system and test it , Further improve the system
2. advantage ： Developers and users are always involved in the process of development , If you have any questions, you can modify them at any time , Meet customer needs
3. Scope of application ： It is suitable for the development of knowledge software system
4. characteristic ： The overall structure is not as clear as waterfall
The document of software is not as strict as waterfall
Long cycle , High cost
Meet users quickly , High development efficiency
five , Spiral model
Rotate along the helix , Four quadrants express four aspects respectively
Designated plan ： Define software goals , Select the implementation plan , Clarify the constraints of project development
risk analysis ： Analysis of options , Consider how to identify and eliminate risks
Implementation project ： Implement software development
Customer evaluation ： Evaluate development work , Proposed amendments
six , Fountain model
characteristic ： iteration
repeat . evolution , No gap
seven , Transformation type ：
Have strict mathematical theory and formal technical support , But it is still in the research and experimental stage , Not practical
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