Web Database Applications with PHP, and MySQL

Appendix B. Internet and Web Protocols

In this appendix, we introduce the networking protocols and standards of the Internet. The first part give a brief overview of the networking protocol TCP/IP and its basic principles. The second, larger part of this appendix is a discussion of HTTP.

The introduction is brief, and we don’t attempt to cover these topics completely. Appendix E provides pointers to selected resources on the topics of the Internet and web protocols.

The Internet

The Internet had its beginnings in the late 1960s with the development of ARPAnet. A primary goal of ARPAnet was to provide a decentralized network of computing resources that did not rely on any one machine or system to operate; that is, no single point of failure could bring the network down. For a network to achieve this, the topology has to provide multiple paths between the computers connected to the network. Such a topology is shown in Figure B-1. Computers are connected to nodes in the network—or form nodes themselves—and so long as a path can be followed through the links between nodes, the computers can communicate.

Figure B-1. A network topology that provides multiple communication paths

Another feature of ARPAnet was the use of packet switching. Unlike telephone networks, where a dedicated circuit is established to carry the conversation between two parties, ARPAnet carried data between two communicating ...