In an earlier chapter, we took a look at low-level networking communication protocols using sockets. This type of networking is at the heart of most of the client/server protocols which exist on the Internet today. These protocols include those for transferring files (FTP, SCP, etc.), reading Usenet newsgroups (NNTP), sending e-mail (SMTP), and downloading e-mail from a server (POP3, IMAP), etc. These protocols work in a way much like the client/server examples in the earlier chapter on socket programming. The only thing that is different is that now we have taken lower-level protocols like TCP/IP and created newer, more specific protocols on top of it to implement the higher-level services we just described. |