Overview

Writing a Web server is easy. You just parse URLs, return files nothing to it. (http://www.nenie.org/cpcip/httpd.txt has the source code of a minimal Web server in only 481 lines of Z80 assembly language, including plenty of white space for readability. It runs only on the Amstrad CPC, though. Web servers of comparable length have been written in Perl and Python.)

On the other hand, if you want the server to be fast, secure, robust, and capable, the job is a good deal harder.

You may recall that Tim Berners-Lee at CERN, the European high-energy physics research lab, invented the World Wide Web. (Not to be confused with the Internet, which predated the Web by many years. The Web is a set of protocols that runs on top of the Internet.)

The Web uses the HyperText Transfer Protocol (HTTP), so a typical name for a Web server is HTTPd, with the "d" standing for "daemon." (A "daemon" an essential concept on UNIX systems is a program that runs in the background, listening until it recognizes that it needs to do something, and then doing it.) The first HTTPd was developed at CERN; the first non-European Web server was installed at SLAC (www-slac.stanford.edu) in December 1991. HyperText had been around as an idea for a long time, arguably since 1945, but Berners-Lee's major insight, articulated in a 1989 proposal, was seamless linking to remote data.

CERN developed servers that ran on big IBM mainframes, on UNIX systems, and on VMS systems. Eventually, however, CERN...