Apache's HTTP server has been by many measures the most popular web server on the web, and perhaps the primary application that drives people to Linux and open source. Three years ago, Wrox published the definitive book on running the Apache server by Peter Wainwright. Excellent though the book was, it badly needed updating. In May 2002, Wrox published another book, Professional Apache 2.0, which covers the new generation of Apache server, as well as older 1.3x versions that are still running production servers around the world."
Although Apache changed a great deal in its version 2.0, it is a credit to the Apache folk that the config files and command line options have basically remained the same for sys admins. For this reason, the book seems to include a lot of material (CGI security, building, core modules) from the original book. However, a closer look reveals many changes. Almost every chapter includes a discussion about how features differ in both versions of Apache. The book does a good job of giving an overview of Apache's architectural changes and how the use of multi-processing modules (MPM) allow the admin to choose an optimal implementation of apache. This edition, noticeably bigger than the previous one, contains many more examples of how one can extend apache functionality (configuring for binary distribution, setting up virtual interfaces, load sharing). Many sections have been expanded. The discussion of security and SSL is more detailed, yet more succinct; so is the section on content negotiation, (which is twice as long as the previous book), doing proxy server configurations, rsync and benchmarking performance. The discussion on hardening the server was great and up-to-date, although I wish the book spent more time discussing on patching and upgrading.
What is new to the book? We find a longer discussion of graphic administration tools for Windows and Unix, including webmin (which actually I wanted more of). We also have discussions of newer modules such as mod_ruby, mod_python, mod_dav as well as a brief description on how to install tomcat alongside apache. The discussion of mod_dav was especially helpful and interesting to me (and I was especially glad that the author acknowledged the Subversion DAV module, something which is bound to become more important). The php stuff hasn't changed much (although at the time the book was published, 2.0 compatibility with PHP was still an iffy proposition). The book's discussion of mod_perl isn't significantly different, although it does point out migration issues and some additional features.
Generally, the book is clearly written and contains enough examples to find any configuration you want. A few parts required rereading (especially the part about proxies and proxypasses), and occasionally I needed a better explanation of what the example code was supposed to do.
No book can be everything for everybody, and nobody can accuse the book of not having enough content (it is after all more than 700 pages!). I found myself wishing for other things. The book briefly discussed 2.0's support for ipv6, but I longed for a fuller explanation and a more detailed example (Fortunately, I had seen a good ipv6 tutorial on Linux Journal ). Also, I would have liked more information about other web application servers (like zope that Apache sometimes coexists with, content frameworks (such as cocoon) and other goodies produced by the Apache Foundation. The author might legitimately feel that such subjects lie outside the book's scope, but such topics are becoming more important.
In summary: for newbies who are looking for a guide to start with: this is the definitive book to read. It's definitive and a little imposing, but it is well written and logically arranged.
For people already familiar with Apache 1.3 but looking for more depth about ipv6, php, content frameworks or Tomcat, it might be better to read books on those specific subjects instead of this one. Indeed, Wrox will soon be coming out with a book specifically on Apache and Tomcat.
For experienced system administrators, the material in this book may not be terribly new, but they will still appreciate the variety of configuration examples for managing large numbers of virtual hosts and the convenience of having documentation of the 1.3/2.0 differences at their fingertips.