UML-use case diagram

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• (1) from the perspective of general users
• (2) From the operator's perspective
• (3) from the Administrator's perspective

 
    Drawing a use case diagram is the first step from the software requirement to the final implementation. Its correctness directly affects the user's satisfaction with the final product. In fact, we can also say that use cases are what the participants want the system to do. The use case diagram is a graphical description of the incident. Use Case charts have three functions: (1) Obtaining requirements (2) Guiding tests (3) Guiding other work.
 

The use case diagram is the functional module of the Software. Designers wear and interpret the use case diagram based on the customer's needs. The use case is visible outside the system.
 

 
I can't find the feeling when I draw an example image. I am always confused about the contained relationship, but what is the difference between the extension and the relationship they want to express. Master said, you should not be too entangled in the relationship between use cases. First, you must understand what the use case is, and its top priority is to serve the customer, the developer communicates with the customer through the use case diagram, so that the customer can clearly and comprehensively understand the functions implemented by the new system.
 

 
In my opinion, the use case diagram focuses on the embodiment of the system functions. From this perspective, I drew examples for the three users of the system.
 

(1) from the perspective of general users

(2) From the operator's perspective

(3) from the Administrator's perspective

 

Next, let me explain my understanding of the use case diagram's inclusion and expansion. I also checked a lot of information on the Internet. No matter how I checked it, I 'd better explain it myself. During the painting process, you will gradually discover the differences and relationships between them. Both inclusion and extension indicate the relationship between the two use cases. Their differences include some use cases interpreting a use case. The general use case is a verb, while other use cases are his object. In my opinion, the extended relationship is always like an additional feature, which can make our system more flexible and tight. These are all your own ideas. Please correct them if you say something wrong.

Note that you should not forget to explain each use case when writing a use case diagram. You can explain the functions of the use case in a few short sentences, this helps you understand the use case diagram.