Summary of UML diagram of Data Center reconstruction system

Overview

Finally, I have finished drawing the restructured UML version of the data room charging system. In this process, I have learned a lot from the technical and ideological aspects.

 

Technology

For Layer 3, we can regard it as layer 5, which is based on the application of specific development projects. We know that a solution can be composed of multiple projects, and a project is equivalent to a component. When developing a project, we create five projects, namely the U layer, b, d, model, and common layers, so that each group can develop different projects at the same time and assemble them together.

The class in the model memory is mainly used as a parameter or attribute, so that the transfer between the layer and the layer changes from a single data type to an object, this will be very helpful for future changes, because they only have one template and you can control it. There are only attributes in the class in the model, and there is no method. The attributes in a class are mainly set of record types in the database table. Of course, there are not the same records as the tables in the database, depending on the situation, the class name in the model needs to be well defined.

In the U layer, the interface class is used to beautify the interface, and then a function is completed using the method in the D Layer class.

The method in the D-layer class is to deal with the database directly. Generally, a table corresponds to a D-layer class. In this case, you can only communicate with one table at a time, if you need to deal with multiple tables at a time, you can create a class at Layer d to execute the stored procedure, so that you can return fields in multiple tables at a time.

The common layer is used to store the string required by layer D, which is a constant. The string is a separate SQL statement, a stored procedure, a table name, or a database connection string, with the common layer, the D Layer won't be able to see SQL statements or stored procedures. In fact, this function has the same function as the model layer, which facilitates easy program modification when the database structure changes, this is because you only need to modify the SQL statements at the common layer once. If you do not need the common layer and the same SQL statements are used more frequently, You need to modify each statement at the time of modification, it is prone to errors.

Layer B is a logical combination of methods in layer D classes to complete a function. It can be said that a specific use case requires a class or method in layer B. Of course, sometimes layer B does not need layer D.

The time sequence diagram describes the sequence of calling methods between classes in the use case diagram.

 

Thoughts

At the beginning, it was very difficult to draw a UML diagram. I kept thinking about the classes and methods in the classes. This is confusing for me, because when I think about some classes and haven't completed all the classes, I began to think about the methods in the classes that I thought, then these two lines are in my mind, so that I didn't figure out the last one, and I felt quite depressed.

After being depressed for a while, I began to write it slowly. First I wrote the classes and methods in my mind, and then I found classes and methods through the time sequence diagram, this process enables me to constantly modify and improve my classes and methods so that I can complete this learning stage. After this stage is completed, I think back to the whole process. I have benefited a lot from the reflection on the above experiences.

If you have many clues when you want to solve the problem, but you do not have a main line, I suggest you write down all the clues, because your clues may be the relationship between different angles and levels, think about it later, think about it later, think about it, think about it, and don't let it go. In this way, they will get tighter and tighter, the more complex you are, the less you can think of them. This idea is not self-conscious for us, and it is very difficult for us to avoid them at once. Therefore, when we encounter such problems, please write them down, read them, write them down, and think again.

 

Summary

Although the UML diagram of the personal rebuild version of the data room charging system is finished, it is not very good and will be modified later.