12.2 The World Wide Web and the Hypertext Transfer...

The existence of the World Wide Web (WWW) is a major factor behind the recent evolution of the Internet. The NCSA Mosaic package is the first graphical user interface to the WWW to gain widespread acceptance in 1993. From that time WWW traffic on the Internet has been growing at an explosive rate, far faster than any other kind of traffic (e.g., SMTP email, FTP file transfers, Telnet remote terminal sessions, etc.) (Zwicky, Cooper and Chapman 2000).

HyperText Transfer Protocol (HTTP) is the protocol that the web is based on. The HTTP protocol itself is a relatively secure protocol and a straightforward one to allow through firewalls. Average HTTP server runs dozens of external programs; they often come from multiple sources and are written in multiple languages. It's not unusual for a single page to involve three or four layers of programs. For instance, the web server calls an external program written in Visual Basic, which uses Jet to access a database server. In many cases, the people writing web pages are using libraries and may not even be aware what other programs are getting run. Figure 2 shows one configuration where a simple query to a web server involves multiple programs (Zwicky, Cooper and Chapman 2000).

12.2 The World Wide Web and the Hypertext Transfer...