C / S is also called Client / Server or Client / Server Mode. Servers typically use high-performance PCs, workstations, or small machines, and use large database systems such as Oracle, Sybase, Informix, or SQL Server. The client needs to install a dedicated client software. B / S is an abbreviation of Brower / Server, just install a browser, such as Netscape Navigator or Internet Explorer, such as Netscape Navigator, or Internet Explorer, and a database such as Oracle, Sybase, Informix, or SQL Server. The browser interacts with the database with the database. The advantage of C / S is to give full play to the processing power of the client PC, and many work can be submitted to the server after the client is processed. The corresponding advantage is that the client response speed is fast. Disadvantages have the following: only applicable to LAN. With the rapid development of the Internet, mobile office and distributed office is increasingly popular, this requires our system to have scalability. This approach to remote access requires specialized technologies, while dedicated design to handle distributed data. The client needs to install a dedicated client software. First, the workload of the installation is involved, and after any computer problem, such as viruses, hardware damage, need to be installed or maintained. Especially there are many segments or specialty stores, not the problem of workload, but the problem of the distance. Also, when the system software is upgraded, each client needs to be reinstalled, and its maintenance and upgrade cost is very high. The operating system for the client generally has limited restrictions. It may be adapted to Win98, but cannot be used for Win2000 or Windows XP. Or do not apply to Microsoft's new operating systems, etc., more don't say Linux, UNIX, etc. The biggest advantage of B / S is to operate anywhere without installing any specialized software. As long as there is a computer that can be internetrated, the client is zero maintenance. The system's extension is very easy, as long as you can access the Internet, you can use the system administrator to assign a username and password. You can use it. Even online applications, after the company's internal security certification (such as CA certificate), the system can automatically assign an account to the user to enter the system. What is the N layer structure? What is the advantage? A: The four layers of the N layer architecture refers to the presentation tier (representing the layer, the interface directly in front of the user), the Web Server Tier, Application Server Tier (Application Server) and Data Tier (Data Layer) The N layer structure is relative to the two layers. Traditional C / S calculation is based on two-level mode. In this mode, all forms of form logic and business logic have resident in the client side, while Server is a database server, responsible for processing and maintenance of various data. Therefore, Server becomes "thin", called "Thin Server". In contrast, this mode requires a huge application in the client, which is called "Fat Client". This structure has the following main problems: First, the reliability of the system has decreased. A client / server system is a mixture of various hardware and software that is independently developed, manufactured and managed, and its inherent reliability is not as good as a single, central management of large-scale machines or small machines, it is difficult to immediately Get technical support and help. Second, the maintenance cost is high.
