Software development three-tier architecture model learning

Three-tier architecture for software development:

Understanding of the three-tier architecture:
Waiter-chef-logistics staff (materials provided)
The UI presentation layer--BLL The business logic layer--dal The data access layer (what knowledge points each layer needs to learn)
UI Presentation Layer:
Displaying data and receiving user input

BLL Business Logic Layer:
Processing user input information;
or send the information to the data access layer for saving;
Or read the data from the database through the data access layer.

Dal Data Access Layer:
Save and read operations on data

Assignment of responsibilities at all levels of the three-tier architecture (do not do extra work)
Presentation Layer (UI): Only the data entered by the user is received and the results of the business logic layer processing data are displayed to the user.

Business Logic Layer (DLL): only responsible for the business processing of data, developers do not write access to the database SQL statement in the business logic layer. The business logic layer can validate the data entered by the user, cache the data read from the database, and so on.

Data access Layer (DAL): It is best to avoid any code that is related to business logic and interface design. That is, to ensure that the functions of the methods in the data access layer are only responsible for storing or reading the data.

Purpose of using the three-tier architecture:
The Software development work Division is more clear, facilitates the later maintenance and the upgrade
The advantage of the three-tier architecture is that the software development tasks can be fully decomposed to facilitate teamwork development
For example, changes to the user interface do not affect the business logic layer and the data access layer, and the interface is available

Software development three-tier architecture model learning