Nov 99 Online
Volume Number: 15 (1999)
Issue Number: 11
Column Tag: MacTech Online
by Jeff Clites <email@example.com>
Apache, Of Course
Over the past several months we've touched on a variety of software packages which originated within the open-source and Unix communities, but which are poised to become important to the Macintosh with the advent of the Unix-based Mac OS X family. But we haven't yet covered one of the most important pieces - Apache. Despite all of the press which Linux gets, the Apache web server is probably the most successful open-source project of all time. To quote the famous statistic (from the Netcraft Web Server Survey), it serves over 55% of the sites on the internet, which according to the Apache FAQ amounts to over 3 million servers.
The Apache Software Foundation
The Netcraft Web Server Survey
The Apache Server FAQ
On the face of it, there isn't much to talk about-Apache comes preinstalled with Mac OS X Server, and it just works; you don't have to port, compile, install, or really even configure it. If you are only interested in serving static HTML pages or WebObjects applications, you barely have to lift a finger. But if you want to go further and write modules for your web server's plug-in API, or take advantage of the availability of its source code, then the fun begins.
As your first step in going beyond the basics, you'll probably want some general information on running and administering Apache. The best place to start is Apache's online user manual, of course. For those who prefer printed material, O'Reilly and Associates has published Apache: The Definitive Guide (ISBN 1-56592-528-9), and there's even a sample chapter (on security) on their web site. If you prefer a more nuts-and-bolts reference, the Apache Server Administrator's Handbook (ISBN 0-7645-3306-1) looks promising. For those interested in diving into Apache's source code, check out Apache Server Commentary: Guide to Insider's Knowledge on Apache Server Code (ISBN 1-57610-468-0), which explains the innards in great detail.
Apache User's Guide
Apache: The Definitive Guide
A great source for ongoing information is the Apache Week ezine, published every Friday. Recent issues have covered a variety of useful topics, notably an heads-up on what's coming in Apache 2.0 (and why a 2.0 version is needed at all), and an introduction to HTTP/1.1. And be sure not to miss their Hints and Tips section, which answers those questions you were just about to ask, and their very nice Links page, which will point you to a wealth of resources on server-related standards and technologies as well as further information about Apache itself.
Apache 2.0 Preview
HTTP version 1.1
Apache Hints and Tips
Apache Related Links
Once you know what it does, it's time to start mucking with it (the programmer's credo). As I touched on above, Apache has its own plug-in API; by writing Apache modules you can intercede at any of the eight steps of its request-handling process. This is similar to Netscape's server API, NSAPI, although Apache's approach lets you step in at a few more places. (If you are familiar with WebObjects' request-response loop, the process is conceptually very similar.) Apache takes this plug-in approach seriously, and in fact uses it to implement some of what could be considered the core functionality of a server-for instance, access to CGIs is handled by the mod_cgi module. Another important example is the mod_WebObjects module provided by Apple as a better-performing alternative to the default CGI-based adaptor for serving WebObjects applications. Check out the Apache API notes (again part of Apache's own documentation) for an introduction, and a paper which Robert Thau presented at the Fifth International World Wide Web Conference for an explanation of the considerations behind its design.
Apache API notes
Design considerations for the Apache Server API
You can write Apache modules in C, but you can also write them in Perl, and if you are familiar with Perl or are interested in learning it, this is a perfect place to apply it. Perl's text-manipulation facilities and high-level data structures, combined with its own large body of powerful community-developed libraries, can make quick work of seemingly complex tasks. A great resource for learning about writing Apache modules comes once again in the form of an O'Reilly book, Writing Apache Modules with Perl and C (ISBN 1-56592-567-X), which will give you the full scoop on writing modules to extend Apache's functionality. (I'm beginning to sound like a broken record, but I promise I'm not on O'Reilly's payroll.) Several of its chapters are available online on the author's accompanying web site.
Writing Apache Modules with Perl and C
Also, check out the Apache/Perl Integration Project site for more information about mod_perl. In addition to letting you write Apache modules in Perl, this module improves the performance or Perl-based CGI scripts by embedding a Perl interpreter within Apache itself, and caching scripts in such a way that they can respond to requests without the overhead of launching the interpreter and compiling the script again each time. (Usually, web servers handle CGI requests by launching the CGI application again for each incoming request.) Although this does require you to rewrite your CGI scripts slightly, the speedup can be dramatic, especially for short scripts, whose startup overhead consumes much more time than actually generating the response.
The Apache/Perl Integration Project
Although Mac developers don't need to worry about having to port Apache, that doesn't mean that there isn't work to be done. There are a number of spin-off projects which could use a hand, and the Apache GUI project, for instance, just has Macintosh written all over it. So if you want to get your hands dirty with the open source community, then check out the Related Projects page and you might find something which grabs your interest. (Java servlets, anyone?) And don't forget, working on a piece of software with millions of grateful users can do wonders for your résumé.
Projects of the Apache Software Foundation
Apache GUI-Dev Project
It will be interesting, going forward, to see how Apple manages to make its server offering into an actual product, since it is based around tools you can get elsewhere for free. One approach is to provide a rich set of management tools which liberate you from the vagaries of complex configuration files. This seems to be the approach taken by Tenon Intersystems, vendors of WebTen, which brought Apache to the classic Mac OS by providing a Unix emulation environment. For Mac OS X Server they have developed iTools, which brings web-based configuration to Apache and provides additional services (such as DNS and SSL). For the near future, iTools is probably the easiest way to access and manage some of Apache's more advanced features, such as virtual hosting.
If Apache's popularity and openness have failed to win you over, you might want to explore your options. Netcraft has an extensive list of links to web server companies, and you can probably find any server you've ever heard of listed here. For a little more guidance, intenet.com's WebServer Compare site lets you search for a server based on the features you want, or you can just look at their quick compare list to get and idea of what's available. Finally, the World Wide Web FAQ has brief descriptions of a number of popular servers-it's a bit out of date but still a good place to start if you really are not sure what server you want to use. Most of the servers listed on this site will be Unix-based, but if you are looking to replace Apache then I am going under the assumption that you are operating under Mac OS X Server. You have a smaller range of choices if you want to run your server under the "classic" Mac OS, but that's a topic for another column.
Netcraft's Directory of Web Server Home Sites
WebServer Quick Compare
World Wide Web FAQ
Finally, if you just want to update your Mac OS X Server Apache installation to the latest version, check out the article on Stepwise, which tells you how to do it and what to watch out for.
Building Apache 1.3.9 for Mac OS X Server
Once you've set up your server, come to ours and visit the MacTech Online web pages at www.mactech.com/online/, where you'll find links to even more useful things.