HP Rp7410 BSD Sockets Interface Programmer's Guide - Page 86

Using Internet Datagram Sockets Overview Overview Internet UDP datagram sockets provide bidirectional flow of data with record boundaries preserved. However, messages are not guaranteed to be reliably delivered. If a message is delivered, there is no guarantee that it is in sequence and unduplicated, but the data in the message are guaranteed to be intact. Datagram sockets allow you to send and receive messages without establishing a connection. Each message includes a destination address. Processes involved in data transfer are not required to have a client-server relationship; the processes can be symmetrical. Unlike stream sockets, datagram sockets allow you to send to many destinations from one socket, and receive from many sources with one socket. There is no two-process model, although a two-process model is the simplest case of a more general multiprocess model. The terms server and client are used in this chapter only in the application sense. There is no difference in the calls that must be made by the processes involved in the data transfer. For example, you might have a name server process that receives host names from clients all over a network. That server process can send host name and internet address combinations back to the clients. This can all be done with one UDP socket. The simplest two-process case is used in this chapter to describe BSD Sockets using datagram sockets. The following table lists the steps involved in exchanging data between datagram sockets. 86 Chapter 4