Performance isn't all that matters when choosing a Web server architecture; it's important to factor the availability and quality of development technologies into your decision if you plan to run a Web-based application or a Web-based business.

Some development technologies are built into one or more Web servers and can be language-independent, such as the Common Gateway Interface (CGI). Some depend heavily on the available development tools, such as ActiveX components that are mostly developed using Microsoft Visual Studio.

There are many excellent Web development options that we do not address in our evaluations--we decided to focus on the Web servers and their associated offerings here rather than on Web development options in general.

Which is right for you? There's no single answer. Microsoft shops will invariably use IIS's excellent set of development tools, while more independent-minded programmers may prefer the free and widely supported Apache and PHP. Java developers, meanwhile, will be hard-pressed to find a better environment than Netscape (iPlanet) Enterprise Server, with its support for the most cutting-edge Java tools.

Apache Server and PHP
For application development, Apache and PHP are my favorites. The documentation is abundant, and the support from users is phenomenal. The stability, especially on a Unix server, is unparalleled. Source Code Control can be performed using the freely available CVS tools. If your shop is not committed to IIS or Java, give Apache, PHP and mySQL on a Linux server serious consideration.

From simple to complex applications, Apache Web server provides several options for developing code. The old-fashioned CGI (Common Gateway Interface) in conjunction with Perl, C or any other language will handle simple forms at low-traffic sites. These programs are spawned in a separate process and thus typically add considerably to the overhead of running your Web application.

Like Netscape and IIS, Apache has an API to make up for CGI's deficiencies. Using the Apache API, programmers can write a piece of software according to a certain structure in C. This piece of code, called a module, can then be linked to the Apache distribution or loaded dynamically at run time. Using C function calls, the programmer has direct access to many of Apache's inner workings. This option is available for both Netscape (through the NSAPI) and IIS (through ISAPI) but has been used most under Apache by developers all over the world. If you venture down that road--for example, if your application needs to process large data sets--check out mod_example.c in the Apache distribution's/modules directory. A special module known as mod_perl allows you to write other modules in Perl instead of C.

We prefer writing dynamic content for Apache with PHP, an Open Source, free server-side HTML-embedded scripting language. PHP provides a programming approach similar to ASP, but its broad support of databases gives it an edge over VBScript. PHP allows you to embed code into your HTML page that's executed on the server. The client never sees the PHP code. PHP's syntax resembles C's and is easy to learn for any programmer with C or Perl background. It allows for complex data structures such as arrays and classes and, because it supports so many databases, it enables the development of large applications only in PHP.

PHP also has ease of use on its side. Writing a database-enabled Web application is simple. Such an application consists of a form in an HTML page that invokes a PHP script, which can open a database connection using a single statement specifying a server name, a user name and an optional password. The code can then perform a SQL query to return all the addresses matching the query submitted through the form. The result is a database result set that can be iterated by using a PHP loop, printing out the information to a resulting HTML page using the built-in echo() and printf() functions. This all takes about six lines of PHP scripting. The end user never sees more than an HTML page with a list of names and addresses in it, since all PHP code has been preprocessed on the server.

More complicated Web applications--especially full-fledged Web clients that replace existing fat clients--require the use of sessions. ASP has provided the concept of a session for a long time, and PHP4 now includes them. Sessions eliminate the need to keep writing and reading cookies to figure out where a user has been. Instead, you store relevant information in a session variable. These variables, along with unique session IDs, let you write complex applications that cater to users' needs while you track their activities.

Send your comments on this article to Gregory Yerxa at gyerxa@nwc.com.