基于信息系统的原则，系统架构模型可分为三层：用户界面层，业务层，数据访

Based on the principles of information systems, the system architecture model can be divided into three layers: user interface layer, business layer, and data access layer, as shown in Figure 4-6. <br>1. Data access layer: It is mainly the operation layer for the original data (database or text file and other forms of storing data), not the original data, that is to say, it is the operation of the data, not the database, specifically the business logic The layer or presentation layer provides data services. <br>2. Business logic layer: It is mainly for the operation of specific problems. It can also be understood as the operation of the data layer and the processing of data business logic. If the data layer is building blocks, then the logic layer is the construction of these building blocks. <br>3. Presentation layer: It mainly represents WEB mode, and can also be represented as WINFORM mode. If the logic layer is quite powerful and complete, no matter how the presentation layer is defined and changed, the logic layer will provide perfect services.

Based on the principles of information systems, the system architecture model can be divided into three layers: user interface layer, business layer, data access layer, as shown in Figure 4-6.<br>1, data access layer: mainly for the original data (database or text file, such as the form of data storage) of the operation layer, not refers to the original data, that is, the operation of the data, not the database, specifically for the business logic layer or performance layer to provide data services.<br>2, business logic layer: mainly for specific problems of the operation, can also be understood as the operation of the data layer, data business logic processing, if the data layer is a building block, then the logical layer is the construction of these building blocks.<br>3, the presentation layer: mainly represents the WEB way, can also be represented as WINFORM way, if the logical layer is quite powerful and perfect, no matter how the performance layer is defined and changed, the logical layer is perfect to provide services.

Based on the principle of information system, the system architecture model can be divided into three layers: user interface layer, business layer, data access layer, as shown in Figure 4-6.<br>1. Data access layer: it is mainly the operation layer of the original data (the form of storing data such as database or text file), rather than the original data. That is, it is the operation of data, not the database, and provides data services for the business logic layer or performance layer.<br>2. Business logic layer: it is mainly for specific problems, and it can also understand the operation of paired data layer. It can process data business logic. If data layer is building block, then logic layer is the construction of these blocks.<br>3. Presentation layer: it mainly represents web mode, or WinForm mode. If the logic layer is quite powerful and perfect, the logic layer provides services perfectly no matter how the presentation layer is defined and changed.<br>