Datagram socket processes, unlike stream socket processes, are not clearly distinguished by server and client roles. The distinction lies in connected and unconnected sockets. An unconnected socket can be used to communicate with any host, but a connected socket can send data to and receive data from one host only.

Both connected and unconnected sockets transmit data without verification. After a packet has been accepted by the datagram interface, neither its integrity nor its delivery can be assured.

Figure 1 shows the general sequence of calls for socket routines using datagram sockets.

Figure 1. A typical datagram socket session