软件工程导论（第5版）考试知识点汇集（Collection of test knowledge points in Software Engineering Introduction (FifthEdition) )Chapter 1: introduction to software engineering1.1 software crisis: refers to a series of serious problems encountered in the development and maintenance of computer software.The following aspects are shown:(1) it is hard for users to be satisfied with the software developed.(2) the quality of software products is often unreliable.(3) general software is hard to maintain.(4) the efficiency of software production is very low.(5) the cost of software development is more and more big.(6) software cost and development schedule are difficult to estimate.(7) the development of software technology can not meet the needs of the popularization and deepening of computer applications.2. definition of software: software is another part of computer system which is interdependent with hardware. It is a complete set of programs, data and related documents. Software = program + data + document1.2. software engineering definition: an engineering discipline to guide the development and maintenance of computer software.4. basic principles of software engineering:1) strict management with a phased life cycle plan2) adhere to the stage review3) strict product control4) adopt modern programming techniques5) the results should be clearly reviewed6) the development team should be few and refined7) recognizing the need for continuous improvement of software engineering practices5. methodology of software engineeringThe collection of a set of technical methods used throughout the software life cycle is often called methodology.Three elements of software engineering: tools, methods and processes.Traditional methodology; object oriented methodology.1.3 software life cycleA, feasibility analysis and development plan: mainly determine the development goal and feasibility of software.B, requirements analysis: in determining the feasibility of software development, the software needs to realize each function is analyzed in detail.C, design (outline design and detailed design): according to the results of requirements analysis, the whole software system is designed, such as system framework design, database design and so on.D, encoding: converts the results of software design into code programs that can be run by the computer.E, test: after the software design is completed, we must go through rigorous testing, to find the software problems in the whole design process and correct it.F, maintenance: after the software development is completed and put into use, due to various reasons, the software can not continue to adapt to the requirements of users1.4 software process1. traditional waterfall model: is an overall development model, the physical realization of the program is concentrated in the late stage of development, the user can see his product in the end.2. rapid prototyping model: the user can give a complete and accurate description of the demands ituation, according to the group of the basic needs of users, the rapid construction of a prototype (software), and then evaluate the further refinement and adjustment of prototype, which meet the requirements of the users, developers will also make better do understand.3. incremental model: a model that incrementally develops software versions that are progressively improved.4. helix model: spiral model is an organic combination of waterfall model, prototype model and incremental model, and increases the risk analysisFeasibility study of the second chapter2.1 the purpose of the feasibility study: to determine whether the problem in the definition of the problem is worth solving, and whether the problem can be solved under the constraints.The task of feasibility study:(1) the definition of the problem is further analyzed and clarified, and the logical model of the system is derived on the basis of clarifying the problem;(2) from the system logic model, choose several main solutions to the problem, study the feasibility of each solution, and make recommendations for future actions;(3) if the problem has no feasible solution, it is suggested to stop system development; if there is a feasible solution to the problem, a better solution should be recommended and a preliminary plan for the project should be worked out.2.2 content of feasibility study process:(1) technical feasibility: whether the existing technology can realize the system, the existing technical personnel can be competent, the development of the system resources can meet;(2) economic feasibility: is the economic benefit beyond the development cost?;(3) operational feasibility: does the system operate within the user?(4) legal feasibility: whether the new system development infringes on the interests of others, the collective or the state, and whether it violates the laws of the state.Steps of feasibility study?(1) review the size and objectives of the system;(2) study the system currently in use, sum up the advantages and disadvantages of the existing system, and propose the rudiment of the new system;(3) a high-level logic model for deriving new systems;(4) recommended proposal;(5) recommended action policy;(6) writing plan task book (feasibility report);(7) submit a review.2.3 system flow diagram: use graphic symbols to describe each component of the system in black box form2.5 data dictionary: the collection of all objects and their relations in the database.Methods: the top-down decomposition of data, when decomposed to no need to further define, and each project related people are also clear the elements of its meaning, then the decomposition process is over.2.6 cost / benefit analysis cost estimation: the cost of software development is mainly manifested as humanc onsumptionCost / benefit analysis methods: first, estimate costs and benefits; then compare costs and benefits; judge whether to develop from an economic point of view. 1, the time value of money; 2, investment recovery period; 3, net income; 4,investment recovery rate.The third chapter: demand analysis3.1, the task of requirement analysisMission: define the goals of the future system accurately and determine what the system has to do to meet the needs of the users.Requirements composition: business requirements, user requirements, system requirements;3.2, the method of communication with users to obtain requirements: A, interview; B, data flow oriented top-down refinementC, simple application specification technology; D, rapid prototyping software3.3, analysis modeling and specificationComposition includes:(1) Introduction: writing purpose, background description, term definition and reference material, etc..(2) outlining the main functions, constraints, or special needs.(3) data flow graph and data dictionary.(4) user interface, hardware interface and software interface.(5) performance requirements, attributes, etc..(6) other requirements, such as database, operation and fault handling, etc..1) analytical modelingModelIt is a kind of abstraction to understand things and make things, and it is an unambiguous description of thingsConsisting of a set of graphical symbols and rules for organizing these symbols.Modeling methodData model entity relation diagram; function model data flow diagram; behavior model state transition diagram2) specification of software requirementsUsually use natural language + model, complete, accurate and specific description of system data requirements, functional requirements, performance requirements, reliability and availability requirements, error handling requirements, interface requirements, constraints, and reverse demand which may be in the future.3.4, entity relation diagram (E-R diagram)The fifth chapter: overall design5.1 design processSystem design phase: determine the specific implementation of the system; structure design phase: determine the structure of softwareThe main task of the overall design is to complete the design of software structure, determine the relationship between modules and modules of the system.5.2 design principleThe 1. module: the program is divided into independent naming and independent access module, each module to complete a sub function of the modules are integrated together to form a whole, complete function and meet the requirements of users.2. abstraction: the essential nature of abstract transactions, without considering their details for the moment.3. step by step refinement;4. information hiding and localization;5. module independence;5.3 heuristic rules: 1. improve software structure to improve module independenceThe 2. module is moderate in scale 3. proper control of depth, width, fan out and fan in4. The scope of the module should be within the control domain5, reduce the complexity of the interface6, single out, single entry, avoid content coupling7, module function can be predictedThe sixth chapter: detailed design6.1 structure program designClassical definitionThe 3 basic control structures are connected only by sequence, selection and loop, and each block has single entrance and single exit characteristicsComprehensive definitionProgramming method of using GOTOs tatement as few as possible. It is best to use GOTOs tatements only when errors are detected, and should always use forward GOTO statementsThe main task of detailed design?Write the "detailed design instructions" of the software. The work that thesoftware personnel should complete:(1) determine the algorithm for each module, select a suitable tool to express the process of the algorithm, and write the detailed process description of the module(2) determine the data structure used by each module(3) determine the details of the module structure, including the interface to the system and the user interface, the interface to other modules within the system, and the details of the module input data, output data and local data(4) design a set of test cases for each module, so that the module code(i.e. program) is scheduled for testing in the encoding phaseProgram control structure: any program logic can be represented by three basic structures: sequence, selection and loop, and two extension structures, selection and loop.6.2 man-machine interface designPrinciple: 1. system response time; 2. user assistance facility3. error information processing;4. command interactionHuman computer interface design guideGeneral interactive guideGuide to information displayData entry Guide6.3 tools for process design1. program flow chart2. box diagram (N-S diagram)3. PAD diagram - problem analysis diagram4. decision table6.4 data oriented design methods1. Jackson diagram2. improved Jackson graph3.Jackson methodThe seventh chapter: Implementation7.1 codingDefinition: translating software design results into programs written in some programming languageSelect the general guidelines for programming languages:?System user requirementsA compiler that can be usedAvailable software toolsEngineering scale?Programmer's knowledge?Requirements for software portability?The application domain of softwareThe task of coding: using the selected programming language, translating the process description of the module into the source code written in language (source code).Coding style guidelines.(1) source code: including appropriate identifiers, appropriate annotations, reasonable layout and clarity of the program list;(2) data: data structure or data type that the order of standardization; the name of the variable as far as possible;on complex data structures to illustrate the implementation method of the data structure in the program design in the notes.(3) the statement structure is simple: don't save space will write multiple statements on the same line; to avoid the complicated conditions and non condition test; avoid using nested loops and nested conditions; brackets use is to make logical expressions and arithmetic operations in order to clear and intuitive expression.Efficiency: (4) considering the time memory efficiency, input / output running efficiency; in dealing with the relationship between program correctness, clarity and efficiency between the first for the program right after the fast; first for clear and fast; in order to keep the program simple fast; write clearly is not clear "efficiency" sacrifice.7.2 software testing foundationThe goal of software testing is to find out and eliminate the bugs in the software as much as possible, and finally give a high quality softwaresystem to the usersSoftware testing criteria(1) all tests should be traceable to user requirements(2) the test plan should be worked out before the test beginsOnce the requirements model is completed, the test plan can be startedAfter building the design model, you can start designing detailed test scenarios(3) Pareto principle: 80% of the errors found in the test are likely to be caused by 20% of the modules in the program. The problem is how to find these suspicious modules and test them thoroughly(4) start from "small scale" test, and gradually carry out "large-scale" test First, focus on testing a single program module, then focus on testing the integration module cluster, and finally find errors in the entire system(5) test cases should be composed of two parts: input data and expected output results, taking into account both reasonable input and unreasonable input data(6) exhaustive testing is impossibleExhaustive testing is a test that checks all the possible execution paths of a program(7) in order to achieve the best test results, independent third parties should be engaged in the test workSoftware testing methodStatic testing: the basic feature is to analyze, check and review the software, not actually running the software being tested.Dynamic testing: by running software to check the dynamic behavior of the software and the correctness of the resultsSoftware testing steps: 1. module test, 2. subsystem test, 3. system test4. acceptance test5. parallel operation7.3 unit testUnit test emphasis: module interface; local data structure; important execution path; boundary condition; error handling channel7.4 white box testing technologyFirst, logical coverageLogical coverage is the design of test cases based on the logical structure of the program.Statement coverageDecision coverageConditional coverageDecision condition coverageConditional combination coverPath coverage7.5 black box testing technology1. Equivalence class divisionDivide the input domain of the program (all possible input data) into several data classes2. Boundary value analysis3. Error guessing: it is a special case that lists possible errors and errors in the program, and chooses the test plan according to them7.6 debuggingDebugging is the process of eliminating errors after testing errorsThe first step: determine the location of the error (95% workload);The second step: correct mistakes.Debugging approach debugging strategy1. brute force method: print the contents of the memory, looking for the wrong clues, is the lowest efficiency of the program debugging method.2. backtracking: starting from the discovery of the problem segment, manually tracing back to the analysis of the program code, until the error is found.3. reasons exclusion methodIt includes: searching, induction and deduction7.7 software reliability: 1, basic concepts1 reliability (Reliability): the probability of a successful operation of a program within a given time interval according to the specifications.2 availability (Usability): the probability of successful operation of a program at a given time point and in accordance with the specifications.3 correctness (Correctness): the function of the program is correct.The eighth chapter: maintenance8.1 definition of software maintenanceThe process of modifying software in order to correct errors or meet new requirements after the software has been delivered.8.2 characteristics1. comparison between structured maintenance and unstructured maintenance2. The cost of maintenance3, maintenance issues8.3 processIn essence, the software definition and development process is modified and compressed1. Establish maintenance organization2. Maintenance Report3. Maintenance of event streams4. Records of preservation and maintenance5. Evaluate maintenance activities8.4 software maintainabilityMaintenance personnel understand, correct, change and improve the difficulty of the software.1. The factors that determine software maintainability2, documentation - the determinant of maintainability is more important than code.3, reviewThe ninth chapter is an introduction to object oriented methodology9.1 overview9.2 basic concepts of object oriented objectObjects can either be concrete physical entities, or can beartificial concepts, or anything that has definite boundaries and meanings.Object definitionDefinition 1: an object is a set of operations with the same state.Definition 2: an object is an abstraction of something in the problem domain, which reflects the system's ability to store information about it or interact with itDefinition 3: objects: =<ID, MS, DS, MI>Name, operation set, data set, message name collection (i.e. external interface) accepted by objectsCharacteristic ：Data centric, no data independent operations;The object is active: the object is active and not passively waiting to be processed, and the external can only be operated by message request;3. Encapsulation: external operation,It is not necessary to know the data structure and algorithm inside the object;(4) parallelism: different objects independently process their own data, and only communicate with each other by passing messages;Module independence is good: strong cohesion, coupling loose。
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