Software Engineering Document Analysis

software engineering

Software life cycle and software process

1.1 Software life cycle

The stages and processes that software goes through from start to finish are the entire process of software development and maintenance.

1.1.1 The software life cycle includes the following stages:

① Requirements analysis phase: In this stage, software developers need to communicate with customers to understand their needs and expectations, and then convert these needs into software specifications to clarify the functions and performance requirements that the software needs to achieve.

②Design phase: In this phase, software developers need to convert requirements specifications into software design documents, design the structure and modules of the software, determine the algorithm and data structure of the software, etc., and also need to consider the maintainability of the software. performance, scalability and portability.

③Coding phase: In this phase, software developers need to use specific programming languages and tools to write software code according to the requirements of the software design document, and conduct testing and debugging to ensure the correctness and stability of the software.

④Testing phase: In this phase, software testers need to conduct various tests on the software, including unit testing, integration testing, system testing, etc., to discover and repair errors and defects in the software and ensure the quality of the software. and stability.

⑤Deployment phase: In this phase, software developers need to deploy the software into the actual usage environment and perform necessary configuration and installation work to ensure that the software can run and be used correctly.

⑥Maintenance phase: After the software is put into use, software developers need to maintain and update the software to fix errors and defects in the software, add new functions and performance, etc., to ensure that the software can continue to satisfy users. needs and expectations.

Software process

Software process refers to the general term for dividing software development into different stages in the software life cycle, carrying out specific tasks and activities for each stage, and the methods, technologies, tools and specifications for performing these tasks and activities. In software development, the software process is the core of software engineering, which determines the tasks and activities at each stage of the software development process and how to perform these tasks and activities.

2.1 In the software process, it usually includes the following steps:

① Requirements analysis: In the requirements analysis stage, software developers need to communicate with customers to understand their needs and expectations, and convert these needs into software specifications to clarify the functions and performance requirements that the software needs to achieve.

②Design: In the design stage, software developers need to convert requirements specifications into software design documents, design the structure and modules of the software, determine the algorithm and data structure of the software, etc., and also need to consider the maintainability and scalability of the software. and portability.

③Coding: In the coding stage, software developers need to use specific programming languages and tools to write software code according to the requirements of the software design document, and conduct testing and debugging to ensure the correctness and stability of the software.

④Testing: During the testing phase, software testers need to conduct various tests on the software, including unit testing, integration testing, system testing, etc., to discover and repair errors and defects in the software and ensure the quality and stability of the software.

⑤ Deployment: In the deployment phase, software developers need to deploy the software into the actual usage environment and perform necessary configuration and installation work to ensure that the software can run and be used correctly.

⑥Maintenance: After the software is put into use, software developers need to maintain and update the software to fix errors and defects in the software, add new functions and performance, etc., to ensure that the software can continue to meet user needs and expectations.

⑦ Retirement: Software backup and archiving, software uninstallation and cleanup, software evaluation and reporting, resource recycling and reuse are required to ensure that the software does not leave any hidden dangers or sensitive information and provides reusability for subsequent software development projects. H. The decommissioning phase is a crucial part of the software process and plays an important role in ensuring the safety and reliability of the software.

Data Flow Diagram (DFD)

(1) It is a graphical analysis tool used to describe the flow and processing of data in the system. It can help analysts clearly understand

Understand the source, destination and processing process of data in the system.

(2) The data flow diagram contains the following three basic elements:

① Entity: Represents the external object with which the system interacts. It can be a person, organization, equipment or other system, etc.

② Process: Represents the operation of processing data, which can be calculation, sorting, filtering, conversion, etc.

③Data Flow: Represents the flow of data in the system, which can be input, output, transmission, storage, etc.

Data flow diagrams can be divided into the following levels:

① Level 0 data flow diagram: Also called context data flow diagram, it is the highest level diagram in the system. It is used to describe the interaction between the system and the outside world and display external entities, data flows and systems.

② Level 1 data flow diagram: Based on the level 0 data flow diagram, it further expands the internal details of the system and describes the main processes within the system, which usually consists of 3 to 7 processes.

③Level 2 data flow diagram: Based on the level 1 data flow diagram, it further expands the internal details of the system and describes the internal processing of the level 1 process, which usually consists of 3 to 7 sub-processes.

Data flow diagrams have the following advantages:

①Easy to understand and use: Data flow diagram uses a graphical method to clearly describe the flow and processing of data in the system, making it easy for people to understand and use.

② Facilitate analysis and optimization: Data flow diagrams can help analysts deeply understand the functions and processes of the system, discover problems and bottlenecks, and thus optimize and improve the system.

③Easy to communicate and communicate: Data flow diagram is a universal graphical analysis tool that can provide different people with a common perspective and language to facilitate communication and communication.

④Easy to maintain and update: The data flow diagram can clearly describe the data flow and processing process in the system, facilitating subsequent maintenance and updates.

However, data flow diagrams also have the following disadvantages:

①Complexity: Data flow diagrams can become very complex, especially in large software systems. This can make understanding and maintaining data flow diagrams more difficult.

②Abstraction level: The data flow diagram has a high level of abstraction and may not be intuitive enough. This may cause some users to have difficulty understanding the meaning of the data flow diagram.

③Lack of details: Data flow diagrams usually only show the high-level processes in the system and ignore specific details. This may cause difficulties for developers when implementing the process.

④Not applicable to some systems: Data flow diagram may not be applicable to some systems, such as concurrent systems or real-time systems. The special nature of these systems may make the design of data flow diagrams difficult or infeasible.

Object-oriented requirements analysis

The object-oriented requirements analysis method is a requirements analysis method based on object-oriented thinking. It represents the entities, attributes, behaviors and relationships between them in the problem domain as concepts such as objects, properties, methods and messages, thereby better Understand and describe the problem domain.
Specifically, the object-oriented requirements analysis method includes the following steps:

①Conceptual modeling: Conceptual modeling is the process of identifying and describing entities, attributes, and relationships in the problem domain. This can be done by using graphical tools such as UML class diagrams or ER diagrams to build conceptual models. The conceptual model should include all entities in the problem domain, their relationships and attributes.

② Functional modeling: Functional modeling is to identify and describe the functions that the system needs to complete based on the conceptual model. This can be done by using graphical tools such as use case diagrams or activity diagrams to model the functionality. The functional model should include all functional requirements of the system and the relationships between them.

③ Behavior modeling: Behavior modeling is to identify and describe the behavior of the system based on the functional model. This can be done by using graphical tools such as state charts or sequence diagrams to model behavior. The behavioral model should include all states of the system, transitions between states, and the behavior of all objects in the system.

④Interface modeling: Interface modeling is to identify and describe the user interface of the system based on the functional model and behavioral model. This can be done by using graphical tools such as interface prototypes or UI flow charts to build interface models. The interface mockup should include the design and layout of all user interfaces.

⑤Verification and validation: Verification and validation is the process of verifying and confirming the system requirements. This can be done by using prototyping systems, simulators or testing tools, etc. The result of verification and validation should be confirmation of all requirements and feasibility analysis of the system.

Through the above steps, the object-oriented requirements analysis method can help developers better understand and describe the problem domain, and transform these requirements into achievable software systems. In addition, object-oriented requirements analysis methods can also make software systems easier to maintain and expand to meet changing needs.

White box testing method

White box testing is a software testing method that is based on understanding the internal logic of the system, designing and executing test cases to verify whether the system performs as expected. The white-box testing method is also called structural testing or logic-driven testing. It can help developers discover and repair potential problems in a timely manner during the development process, and improve the quality and reliability of software.
The main steps of the white box testing method are as follows:

① Review of program code: The first step of the white box testing method is to review the program code and understand the internal logic and data structure of the system. This includes reviewing source code, documentation, comments, and other relevant information to better understand the structure and functionality of the system.

② Design test cases: Based on the review results of the program code, design test cases to check whether the system meets the expected functional and performance requirements. Test cases should cover all code paths, including those under normal circumstances and those under abnormal circumstances.

③Execute test cases: Execute tests according to test case design and record test results and problems. During the testing process, it is necessary to carefully observe the behavior of the system, including input, output, state changes, etc., in order to better understand the operating status of the system.

④ Analyze test results: Analyze test results and determine the cause of the problem. If the test results are not as expected, you need to take a closer look at the code and test cases to determine the cause of the problem. If the test results are as expected, the test cases and code can be further optimized and improved.

⑤ Fix the problem: Fix the problem according to the test results, and retest to confirm that the problem has been solved.

(3) The advantage of the white box testing method is that it can discover potential problems and errors and improve the quality and reliability of the software. It can also help developers better understand the internal logic and data structures of the system for better code writing and debugging. However, the white-box testing method requires an in-depth understanding of the structure and logic of the program code, requires high developer skills, and the testing cost is relatively high.

Black box testing method

(1) Black box testing is a software testing method that does not consider the internal logic of the system and only focuses on the input and output of the system to verify whether the system performs as expected. The black box testing method is also called functional testing or data-driven testing. It can help testers conduct testing without knowing the specific implementation of the system, discover system defects and problems, and ensure that the system's functions and performance meet expected requirements.

(2) The main steps of the black box testing method are as follows:

① Determine test requirements: Determine the purpose, scope and test requirements of the test. This includes determining the inputs, expected outputs, and test conditions of the test to better design and execute test cases.

② Design test cases: According to the test requirements, design test cases to verify whether the system performs as expected. Test cases should cover all possible input situations and boundary conditions to catch potential problems and errors.

④ Analyze test results: Analyze test results and determine the cause of the problem. If the test results are not as expected, you need to take a closer look at the test cases and test conditions to determine the cause of the problem. If the test results are as expected, the test cases can be further optimized and improved.

⑤ Fix the problem: Fix the problem according to the test results, and retest to confirm that the problem has been solved.

The advantage of the black box testing method is that it can test the function and performance of the system without knowing the implementation details of the system. The skill requirements of the testers are relatively low, and the testing cost is also low. However, the black box testing method may not be able to capture problems and errors within the system. The design of test cases needs to carefully consider the input and output of the system, otherwise it may be full of loopholes. Therefore, black box testing methods need to be used in conjunction with other testing methods to obtain more comprehensive test coverage and higher test quality.

Software project management

Software project management refers to planning, organizing, directing, controlling and evaluating various activities in the software development process to achieve software project goals and requirements.
Software project management process and content include the following aspects:

①Project initiation stage: Determine the project goals, scope, requirements, resources, schedule and risks, etc., formulate the project plan and organizational structure, and clarify the project execution process and quality standards.

② Requirements analysis stage: collect, analyze and clarify user requirements, prepare requirements specifications, formulate requirements change management plans, and ensure that project requirements meet user requirements and expectations.

③Design stage: Carry out system design, module design and interface design according to the demand specifications, prepare design documents and test plans, and ensure that the system design meets the demand specifications and quality standards.

④ Coding and testing stage: Carry out software coding and testing activities according to the design documents and test plans to ensure that the code quality and functions of the software meet the requirements of the design documents and test plans.

⑤Integration and acceptance stage: Integrate and system test each module and conduct system acceptance to ensure that the functions, performance and quality of the software system meet user requirements and expectations.

⑥Project closure stage: Complete project delivery, closing and summary work, including project acceptance, document archiving, knowledge management and experience summary, etc.

The collective content of software project management includes the following aspects:

①Project plan management: Develop project plan, including project progress

degree, cost, quality, scope, resource and risk management plans, etc. to ensure that the project is executed according to plan.

②Quality management: Develop quality standards and test plans, test and evaluate the functions, performance, reliability and security of the software system to ensure that the quality of the software system meets user requirements and expectations.

③Change management: Develop a change management plan to manage and control requirements, design, code and testing to ensure that changes to software systems comply with quality standards and safety requirements.

④Risk management: Identify, evaluate and control project risks, formulate risk management plans, and ensure that project risks are effectively managed and controlled.

⑤Human resources management: Develop a human resources management plan, including project organizational structure, personnel recruitment, training and assessment, etc., to ensure that the human resources of the project team are effectively managed and utilized.

⑥ Communication management: Develop a communication management plan to ensure smooth communication within and outside the project organization, and timely and accurate information transmission and feedback.

⑦ Procurement management: Develop a procurement management plan to manage and control purchased software and hardware to ensure that the quality and cost of project procurement meet requirements and expectations.

(4) The software project management process and content is a complex system engineering that requires comprehensive and systematic consideration of all aspects of factors to ensure that the software project is achieved according to the planned and required goals and expectations.

Software Engineering Document Analysis

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