Besides the early host-terminal structure, what are the database system architectures and which are distributed?

The architecture of software system has experienced the host terminal mode, client/server (C/S) mode, browser/server (B/S) mode and multi-layer distributed structure.

Host/terminal structure:

Early computer systems were mostly stand-alone systems, and many users accessed them through networked terminals, so there was no concept of network. The so-called host time-sharing system. The connected terminal has no transaction processing ability, but only inputs and displays information. All transaction processing functions are completely carried out on the host computer. So the load of the host is very heavy, and the transaction processing ability of the whole system depends entirely on the host. At present, the host/terminal mode is gradually being eliminated.

Two-tier structure-client/server architecture;

The early C/S structure is a typical two-layer structure. According to their different functions, the application is divided into two parts: one part is used to process the database, which is called the server part; The other part is used to process applications and request services, which is called the client part. The client part is responsible for performing foreground functions, such as managing user interface, data processing and reporting requests, while the server part performs background services, such as managing peripheral devices, controlling database operations, accepting and responding to client requests, etc.

The working principle of C/S structure is that the user requests data from the client through the application, and the client submits the user data to the server through the network. The database management system of the server performs data processing tasks, and then transmits the processed data to the client. Finally, the client finishes processing its data and submits the processing result to the server.

Browser/server structure (B/S structure):

B/S is essentially a C/S structure, which is the development of the traditional two-tier C/S structure on the Web. Compared with the C/S structure, the B/S structure separates the application module of the client from the display function, puts the application module on the Web server, and the client only needs to install the browser, so that the business processing part of the system is unified on the Web server, and the client only plays the role of interacting with the user.

The working principle of B/S structure is that the Web server accepts the browser's Web request and processes the web page request, and at the same time, the data request is converted into a form acceptable to the database server through the database interface (such as SQL), which will only be sent to the database server, and the database server performs corresponding database operations (such as query, statistics, modification, etc.) according to the data request.