服务器 = 网络服务器 + 应用架构 + 事务处理单元
服务器是运行着网络事物处理软件的主机；
从广义上讲，服务器是指网络中能对其它机器提供某些服务的计算机系统。
A server is both a running instance of some software that is capable of accepting requests from clients, and the computer that executes such software. Servers operate within a client-server architecture, in which "servers" are computer programsrunning to serve the requests of other programs, the "clients". This may be to share data, information or hardware and software resources. Typical computing servers are database server, file server, mail server, print server, web server, gaming server, and application server.
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