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Apache: The Definitive Guide, Third Edition, is principally about the Apache web-server software. We explain what a web server is and how it works, but our assumption is that most of our readers have used the World Wide Web and understand in practical terms how it works, and that they are now thinking about running their own servers and sites.
This book takes the reader through the process of acquiring, compiling, installing, configuring, and modifying Apache. We exercise most of the package's functions by showing a set of example sites that take a reasonably typical web business — in our case, a postcard publisher — through a process of development and increasing complexity. However, we have deliberately tried to make each site as simple as possible, focusing on the particular feature being described. Each site is pretty well self-contained, so that the reader can refer to it while following the text without having to disentangle the meat from extraneous vegetables. If desired, it is possible to install and run each site on a suitable system.
Perhaps it is worth saying what this book is not. It is not a manual, in the sense of formally documenting every command — such a manual exists on the Apache site and has been much improved with Versions 1.3 and 2.0; we assume that if you want to use Apache, you will download it and keep it at hand. Rather, if the manual is a road map that tells you how to get somewhere, this book tries to be a tourist guide that tells you why you might want to make the journey.
In passing, we do reproduce some sections of the web site manual simply to save the reader the trouble of looking up the formal definitions as she follows the argument. Occasionally, we found the manual text hard to follow and in those cases we have changed the wording slightly. We have also interspersed comments as seemed useful at the time.
This is not a book about HTML or creating web pages, or one about web security or even about running a web site. These are all complex subjects that should be either treated thoroughly or left alone. As a result, a webmaster's library might include books on the following topics:
The Web and how it works
HTML — formal definitions, what you can do with it
How to decide what sort of web site you want, how to organize it, and how to protect it
How to implement the site you want using one of the available servers (for instance, Apache)
Handbooks on Java, Perl, and other languages
Security
Apache: The Definitive Guide is just one of the six or so possible titles in the fourth category.
Apache is a versatile package and is becoming more versatile every day, so we have not tried to illustrate every possible combination of commands; that would require a book of a million pages or so. Rather, we have tried to suggest lines of development that a typical webmaster could follow once an understanding of the basic concepts is achieved.
We realized from our own experience that the hardest stage of learning how to use Apache in a real-life context is right at the beginning, where the novice webmaster often has to get Apache, a scripting language, and a database manager to collaborate. This can be very puzzling. In this new edition we have therefore included a good deal of new material which tries to take the reader up these conceptual precipices. Once the collaboration is working, development is much easier. These new chapters are not intended to be an experts' account of, say, the interaction between Apache, Perl, and MySQL — but a simple beginners' guide, explaining how to make these things work with Apache. In the process we make some comments, from our own experience, on the merits of the various software products from which the user has to choose.
As with the first and second editions, writing the book was something of a race with Apache's developers. We wanted to be ready as soon as Version 2 was stable, but not before the developers had finished adding new features.
In many of the examples that follow, the motivation for what we make Apache do is simple enough and requires little explanation (for example, the different index formats in Chapter 7). Elsewhere, we feel that the webmaster needs to be aware of wider issues (for instance, the security issues discussed in Chapter 11) before making sensible decisions about his site's configuration, and we have not hesitated to branch out to deal with them.
Apache gets its name from the fact that it consists of some existing code plus some patches. The FAQ[1] thinks that this is cute; others may think it's the sort of joke that gets programmers a bad name. A more responsible group thinks that Apache is an appropriate title because of the resourcefulness and adaptability of the American Indian tribe.
[1]FAQ is netspeak for Frequently Asked Questions. Most sites/subjects have an FAQ file that tells you what the thing is, why it is, and where it's going. It is perfectly reasonable for the newcomer to ask for the FAQ to look up anything new to her, and indeed this is a sensible thing to do, since it reduces the number of questions asked. Apache's FAQ can be found at http://www.apache.org/docs/FAQ.html.
You have to understand that Apache is free to its users and is written by a team of volunteers who do not get paid for their work. Whether they decide to incorporate your or anyone else's ideas is entirely up to them. If you don't like what they do, feel free to collect a team and write your own web server or to adapt the existing Apache code — as many have.
The first web server was built by the British physicist Tim Berners-Lee at CERN, the European Centre for Nuclear Research at Geneva, Switzerland. The immediate ancestor of Apache was built by the U.S. government's NCSA, the National Center for Supercomputing Applications. Because this code was written with (American) taxpayers' money, it is available to all; you can, if you like, download the source code in C from http://www.ncsa.uiuc.edu, paying due attention to the license conditions.
There were those who thought that things could be done better, and in the FAQ for Apache (at http://www.apache.org ), we read:
...Apache was originally based on code and ideas found in the most popular HTTP server of the time, NCSA httpd 1.3 (early 1995).
That phrase "of the time" is nice. It usually refers to good times back in the 1700s or the early days of technology in the 1900s. But here it means back in the deliquescent bogs of a few years ago!
While the Apache site is open to all, Apache is written by an invited group of (we hope) reasonably good programmers. One of the authors of this book, Ben, is a member of this group.
Why do they bother? Why do these programmers, who presumably could be well paid for doing something else, sit up nights to work on Apache for our benefit? There is no such thing as a free lunch, so they do it for a number of typically human reasons. One might list, in no particular order:
They want to do something more interesting than their day job, which might be writing stock control packages for BigBins, Inc.
They want to be involved on the edge of what is happening. Working on a project like this is a pretty good way to keep up-to-date. After that comes consultancy on the next hot project.
The more worldly ones might remember how, back in the old days of 1995, quite a lot of the people working on the web server at NCSA left for a thing called Netscape and became, in the passage of the age, zillionaires.
It's fun. Developing good software is interesting and amusing, and you get to meet and work with other clever people.
They are not doing the bit that programmers hate: explaining to end users why their treasure isn't working and trying to fix it in 10 minutes flat. If you want support on Apache, you have to consult one of several commercial organizations (see Appendix A), who, quite properly, want to be paid for doing the work everyone loathes.
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