The meaning of the three-tier architecture, especially English abbreviations, needs to be remembered

The three-layer structure is: 1. Presentation layer (Usl-user Show layers): The main means of the web, or can be expressed as WinForm mode. 　　If the logical layer is quite powerful and complete, the logic layer can provide services perfectly, regardless of how the presentation layer is defined and changed. 2. Business Logic Layer (BLL): Mainly for the specific problem of operation, can also be understood as the operation of the data layer, the data business logic processing. 　　If the data layer is a building block, the logical layer is the building blocks. 3. Data access Layer (Dal-data access layers): Mainly for the original data (database or text files, such as the form of data storage) operations layer, rather than the original data, that is, the operation of the data, rather than the database, specifically for the business logic layer or presentation layer to provide data services.

The meaning of the three-tier architecture, especially English abbreviations, needs to be remembered