面向连接的服务器流程中，必须设置服务器套接字为监听状态；而客户机则是主动连接。无连接客户机和服务器。无连接客户机和服务器在调用的函数方面没有区别，区别在于服务器一般先启动recvfrom等待客户机的数据。客户机和服务器的通信过程为客户向服务器发送数据，服务器收到数据后给予应答，通信结束。-connection-oriented server process, you must set up to monitor server socket state; While the client is active connector. Without connecting client and server. Without connecting client and server in a function called no distinction, the general difference is the server for first launching recvfrom client data. Client and server communication process for clients to send data to the server, the server data received responses and communication end.