Data source layer forwarding three-tier structure

Data Source Layer

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The data source layer (Tier, also called the Data Service layer, the database layer) is used to control the flow of your program, such as what the program shows at a certain stage. These all need logic to control. I hope that with a simple example, you will be able to understand the advantages of using the Noahweb logic layer to control the process. The logical layer represents a computer running a DBMS, such as a SQL Server database. See client layer, middle tier.

The three-tier network structure refers to the process of dividing data into three parts: the first is the client layer (user interface layer), provides the user and the system friendly access, the second layer is the Application service layer (also called the middle layer), the specialized division business logic realizes; The third layer is the data source layer (data service layer, database system), responsible for the storage of data information, Access and its optimizations. Because the business logic is extracted to the application service layer, greatly reduced the burden on the client, so also become a thin client (Thin client) structure, the three-tier structure in the traditional two-tier structure based on the addition of application services layer, the application logic alone to deal with, so that the user interface and application logic on different platforms, The communication protocol between the two is defined by the system itself. With this structure design, the application logic is shared by all users, which is the biggest difference between the two-tier architecture application software and the three-tier application software. Three-tier structure will represent the part and the business logic part according to the customer layer and the Application service layer separation, the client and the Application service layer, the Application service layer and the database service layer communication, the heterogeneous platform data exchange and so on can be realized through the middleware or the related program. When the business logic of the database or application service layer changes, the client does not need to change, and vice versa, greatly improves the reusability of the system module, shortens the development cycle and reduces the maintenance cost. With Java applet as the client, the three-layer network structure with Java servlet as the middle tier has been widely used in the current real-time network information platform, and its structure and general three-layer structure are as shown in Figure 1:

The data source layer defines, maintains, accesses, and modifies data, while managing and satisfying data requests in the middle tier. Separating data source services from other application components enables data structures and access mechanisms to be maintained, modified, and, if necessary, reconstructed without affecting application components at the customer layer and middle tier.

The data binding and RDS technology, combined with the three-tier structure, will be the focus of the next round of dynamic Web technology application development with its unique commercial value. Because of the use of the client's data buffering mechanism, it will give full play to the potential of the thin client, so as to effectively meet the client's complex application needs, significantly reduce the number of network connections, greatly improve the use of browsers to access the Web site background data application effect.

A data source server can be implemented in a specific database management system (DBMS) or a collection of different parts of a federated database belonging to multiple platforms and hosts. For example, your DBMS can be a microsoftsqlserver database and use MICROSOFTODBC and OLE DB technology to handle data from different sources from the client. This eliminates the need for a corresponding customer driver for each data source, and also means that remote Data services can be easily modified to fit any network and database configuration.