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1, to explain the concept of a software life cycle and provide an example to explain its various stages, including production and delivery (not limited to the waterfall model life cycle);
Typically, a software product made from, implementation, operation and maintenance to decommissioning process called stop using the software life cycle. In other words, consider the concept of software products from the beginning to the software product can not use the whole period until the fall of the software life cycle.
The waterfall model is a classic of the software life cycle model, also known as predictive lifecycle, complete plan-driven life cycle. In this model, the project life cycle at the earliest possible time, to determine the scope of the project and delivery time and cost required for this range. In this model, when the project started, the project team focused on the overall scope of the definition of products and projects, and the development of products (and related deliverables) delivery schedules, followed through the various stages to the implementation plan. You should carefully manage project scope changes. If there is new scope, you need to plan and officially confirmed. For constantly changing project, the waterfall model worthless.
Below a secondary trading platform as an example, the software life cycle of six main stages:
1, feasibility studies and planning. To be developed to determine the target software system development and general requirements, given its possible solutions terms of functionality, performance, reliability, and interfaces to develop implementation plans to complete the development tasks.
Target secondary trading platform is to provide a can for the platform user transactions, user perform basic operations and management of personal information registration, login, etc. on this platform; can of commodities to view, search, auctions and other transaction functions; user transactions involving payment , you need to make payment interface, available to users through the micro-channel, Alipay and other financial software transactions.
2, analysis needs. Recognizing the needs of the proposed development of software to analyze and give detailed definition that accurately determine the function of the software system. Writing software specifications and preliminary user manual submission review.
According to user needs, develop a detailed reporting requirements, this step is very important in the waterfall model, it takes as much time to collect user requirements, can also refer to other features of the platform has been achieved.
3 software design. System designers and programmers should be understood that repeated on the basis of software requirements, the structure of the software distribution is given, the division of modules, functions, and processes.
This step needs to be built database software - using the ER diagram, a flowchart of software, data flow diagrams, class diagrams, do a complete report on demand logic design.
4, software. The software is designed to convert computer program code can be accepted. Complete coding source code, writing user manuals, operating manuals and other user-oriented document, write a unit test plan.
This part be achieved coding, that is based on what logic design, implement platform used to build a specific programming language, and be able to run normally.
5, software testing. On the basis of the design of the test cases, test various components of the software. Writing test analysis report.
If the previous work is the design, creation, then this step to do is destroy, in addition to the normal use of the data beyond functional testing, but also for stress testing, boundary testing, the maximum number of users as the platform can bear illegal users to view background data. Find out as much as possible defects in the software, and then repair, then test. To use a combination of white box and the black-box testing. Use as many test sample.
6, operation and maintenance. The software is delivered in operation, and continue to maintain in operational use, and may make the necessary expansion and deletion according to the needs of the newly proposed. Maintenance phase is also the most phases of the software life cycle takes
When all the work is done, the secondary trading platform will be able to put into use, or if the loophole is not suitable for people accustomed to the operation to be revised in the course, which is what we usually see updates and other operations.
2, check the software disaster-related information to the software disaster from start to finish ordering.
Software disaster is due to software bugs caused catastrophic failure --BUG--, resulting in economic harm, political harm, social harm and even endanger the masses, difficult to repair serious harm to social life.
The definition of software defects: Look inside the product, defects are problems errors, problems and other software product development or maintenance of existing in the process; from the outside products, the failure or defect is contrary to the system need to achieve a certain function.
Defect Origin: 1 Defect Defect Defect Defect demand because of a problem caused due to the frame 2. 3. Since the problems caused by design defects caused due to encoding 4. 5. because of a problem caused due to test 6. defects due to problems caused by the integration of
Level defects: 1 minute 2. General 3. 4. deadly serious
Sorting software catastrophic event occurred in recent years:
1. Mariner (Mariner) fatal BUG (1962)
2. Hartford stadium collapse event (1978)
3. CIA to send natural gas to the Soviet Union (1982)
4. Almost lead to World War III (1983)
The medical instrument death case (1985)
6. Wall Street crash (1987)
7. AT & T phone off the network (1990)
8. Patriots live up to the soldier (1991)
9. Pentium long division defect (1993)
10. Ariane rocket explosion (1996)
11. Skynet brought the end of the world (1997)
12. Mars Climate Orbiter crashed (1998)
13. Disaster Research (1999)
14. British passport missing (1999)
15 years of the War Y2K (1999)
16. Bomb (Dot-Bomb) crash (2000)
17. Love Bug (2000)
18. For the treatment of cancer death (2000)
19. EDS abandoned support for children (2004)
20. FBI trilogy End (2005)