什么是主从架构

电脑网路架构，众多客户端（远端处理程序）请求并接受中央伺服器（主电脑）的服务。客户端电脑提供界面让电脑使用者请求伺服器提供服务，并显示伺服器送回的结果。伺服器等待从客户端来的请求，随即加以回应。理想上，伺服器提供标准化的透明界面给客户端，客户端不需要知道提供服务的系统详细资料（亦即硬体和软体）。现今的客户端通常安置在工作站或个人电脑上，伺服器则位於网路的另一处，通常是在功能更强大的机器上。这种计算模式在客户端和伺服器经常任务的区隔清楚时才特别有效率。例如医院的资料处理，客户端电脑可能是执行应用程式输入病人资讯，而伺服器是执行另外的程式管理这些资讯永久储存的资料库。众多客户端可以同时同步存取伺服器的资讯，客户端电脑也能执行其他工作，例如发送电子邮件。因为客户端和伺服器电脑都视为智慧装置，主从模式完全不同於老旧的「主机」模式。主机模式是利用中央主机替相连的「笨」终端机执行所有的工作，

client-server architecture

Architecture of a computer network in which many clients (remote processors) request and receive service from a centralized server (host computer). Client computers provide an interface to allow a computer user to request services of the server and to display the results the server returns. Servers wait for requests to arrive from clients and then respond to them. Ideally, a server provides a standardized transparent interface to clients so that clients need not be aware of the specifics of the system (i.e., the hardware and software) that is providing the service. Today clients are often situated at workstations or on personal computers, while servers are located elsewhere on the network, usually on more powerful machines. This computing model is especially effective when clients and the server each have distinct tasks that they routinely perform. In hospital data processing, for example, a client computer can be running an application program for entering patient information while the server computer is running another program that manages the database in which the information is permanently stored. Many clients can access the server's information simultaneously, and, at the same time, a client computer can perform other tasks, such as sending E-mail. Because both client and server computers are considered intelligent devices, the client-server model is completely different from the old "mainframe" model, which utilized a centralized mainframe computer that performed all the tasks for its associated "dumb" terminals.