Diagram in software engineering

We usually have a special liking for graphical things. When we were a child, the Enlightenment education started from the graphical aspects. We have seen comic books, cartoons, picture-based literacy, and so on.

Because graphics can embody and visualize an abstract object, graphical expressions can clearly present ideas, things, and scientific concepts that cannot be clearly expressed or hard to express in words. This is why we prefer vivid images than obscure words.

Software Engineering is a very important course in the software development process. Only by using software engineering ideas can we develop software systems with high efficiency and high quality. Generally, software development is divided into eight parts: 1. problem definition 2. feasibility study 3. requirement Analysis 4. overall Design (Outline Design) 5. detailed Design 6. coding and unit testing 7. comprehensive Test 8. software maintenance. The following is a diagram of each process.

1.Problem definition

The problem definition stage mainly defines the problems that users need to solve based on their needs and what functions they need to implement.

2.Feasibility Study

The feasibility study stage is to check whether there is a solution to solve the problem at the minimum cost, with the maximum benefit in the shortest time. This stage mainly includes the following figures.

2.1 system flowchart

System flowchart is a traditional tool used to describe the physical model of a system. It represents the flow of data between various components of the system, rather than the control process of data processing. It is a physical data flow diagram rather than a program flow chart. The system flowchart shows the functions of the software. Even if you do not understand the software, you can easily understand it. It can be said that it is an effective tool for communication and communication between software designers and users.

2.2 Data Flow Diagram

A data flow chart is a graphical representation of the system's logical functions, the logical flow of data within the system, and the logical transformation process from the perspective of data transmission and processing, it is the main expression tool of the structured system analysis method and a graphical method used to represent the software model. If the system flow chart allows users to better understand the functions of the system, the data flow chart gives users a better understanding of the operating principles of the system.

2.3 Data Dictionary

A data dictionary is a set of data information, that is, a set of definitions of all elements in the data flow diagram mentioned above. The main function of data dictionary is to facilitate the access to the descriptive information of data that we do not know very well in the software analysis and design phase.

3. Demand Analysis

The requirement analysis stage mainly determines what the system must do. For example, the user's requirements on the system, determine all the functions of the target system, determine the hardware and software environment for the system to run, system performance requirements, error handling requirements, interface requirements, verification software requirements, and so on.

3.1 E-R Diagram

The main function of the E-R diagram is to present the user's data requirements with visual graphics

3.2 status transition diagram

The state transition diagram shows the system behavior modeling, that is, the system behavior is expressed by describing the system status and events that cause state changes, displays detailed status changes during system running to users.

3.5 IPO Diagram

An ipo diagram is short for an input, processing, and output diagram. It clearly describes the relationships between input data, processing data, and output data.

4.Overall Design

In the demand analysis stage, we have determined what the system should do, and the overall design is to figure out how to do the problem. The overall design aims to summarize how the system should be implemented, specifically, it is necessary to clarify the components of the system and the relationship between these modules.

4.1 hierarchy chart

A hierarchy chart is used to describe the hierarchy of software.

4.2 Structure Diagram

Similar to a hierarchy chart, a structure chart describes the software structure.

5.Detailed Design

The detailed design stage is based on the overall design to determine how to implement the functions required by the system in detail, and to accurately describe the system.

5.1 program flowchart

The program flow chart is an intuitive description of the program control process.

5.2 box chart

In order to have a kind of graphics tool that does not allow violation of the Structure Design spirit, nassi and shneiderman proposed a box chart, also known as a N-S chart.

5.3 Problem Analysis pad Diagram

6. coding and unit testing

The coding and unit testing phases mainly describe the detailed description of the detailed design phases for specific implementation and Module Testing.

7. Comprehensive Test

Comprehensive Testing includes testing the components and functions of the system, covering all functional points of the software system, and testing the performance and ease of use of the software based on the needs of the tested software, achieve the purpose of testing all aspects of the software.

8. Software maintenance

The software maintenance phase is the last and longest stage in the software life cycle, the main task of software maintenance is to make some or all modifications to the application based on changes in demand or hardware environment, and make full use of the source program during modification. After modification, you must enter the application change registration form and specify the differences between the new and old procedures in the application change notice.