First, resume
Code link: https: //github.com/fayanddream/resume.git
Second, the discussion
1. Explain the concept of a software life cycle and to provide an example to explain its various stages, including production and delivery (not limited to the waterfall model life cycle).
answer:
Software life cycle is to produce software until retirement or stop using the life cycle. There are problems within the definition of the software life cycle, feasibility analysis, general description, system design, coding, debugging and testing, inspection and operation, maintenance upgrades to disposal phases.
Incremental model is to follow the incremental approach to software development. Software product is as a set of incremental components, each needs analysis, design, implementation, integration, testing and delivery of a member, until the full realization of all the components.
To analyze a business site, for example:
Needs analysis: first need to investigate the needs of the enterprise, e-commerce sites clearly what needs to be done, to what extent, and through access to information, field observations and other methods, will summarize the needs of the site for the functional requirements and performance requirements. Functional Requirements: store publish product information, organize online merchandise, manage orders and so on; consumers buy, online payment, logistics and finally through the deal. Performance requirements: To run the system stable, strong adaptability, portability.
Design: The system is based on requirements of the system design phase the specification, a physical model of the new system design, system partitioning mainly to complete work and database design. This project can be divided into modules landed the account, browse merchandise modules, shopping cart module, order management module, backstage management module. Database design can create four basic table: Product information table, user table, the Orders table, administrator table.
Implementation: From start to realize, incremental model began to be distinguished from the waterfall model. In a particular development, based on division of the design phase of the system, the completion of the core modules of the code page.
Integration: After completion of the development of an incremental member, the member needs to be integrated into the system.
Test: When the new member is integrated into an existing member, i.e., the product formed in the system has changed the re-validation occurs.
Incremental delivery: prioritize development in accordance with the function increments members, one by one to achieve and delivered. Not only help users spend system as soon as possible, better able to adapt to the new software environment.
2. Check software disaster-related information, software to sort of disaster from start to finish.
A: The software severity of the disaster can be summarized as the following four levels:
(1) small (Minor): some minor problems, if any individual typos, irregular text layout, etc., almost no effect on the function, the software product can still be used.
(2) Average (Major): For less severe errors, such as the loss of secondary function module, a message is not accurate enough, the difference between the user interface and long operation time.
(3) severe (Critical): Critical error, refers to the functional module or that are not implemented, the main function of partial loss, the loss of all secondary function, or a fatal error statement.
(4) fatal (Fatal): fatal error, causing the system to crash, crash, or cause loss of data, the main function completely lost and so on.
Software Disaster example:
In 1962, Mariner rocket fatal bug. In 1962, the space probe carrying the Mariner 1 rocket to the Venus. After takeoff deviates from a predetermined route, mission control to destroy the rocket after takeoff 293s, because programmers put a handwritten copy of the formula for the wrong computer code.
In 1987, Hartford stadium collapsed due to the assumption steel roof support program error analysis only withstand the force of pure pressure, after a support collapsed, causing a chain reaction.
In 1983, the Soviet missile warning system error reports were five United States launched missile attack, which nearly led to World War III.
In 2003 the US "Patriot" missiles a few days a series of problems, causing concern for the problems of people aiming system software.
2003 occurred in most parts of the United States and Canada in the history of the largest power outage was caused by an error of power monitoring and control system.
2009 STORM "recall" all the software, caused six provinces off Wang Shi. South six provinces disconnection event, DNSpod server was hacked, resulting in massive STORM user service request can not be resolved, resulting in a chain reaction.
2010, Toyota said, for there is a fault on the black box of software for reading the reader, may result in data recording module records appear inaccurate, misleading the driver to determine vehicle speed when the accident occurred.