Apache: The Definitive Guide, 3rd Edition

Other Approaches to Application Building

While HTML forms are likely the most common use for application logic on web servers, there are many other cases where users interact with applications without necessarily filling out forms. Large sites often use content-management systems to store the information the site presents in databases, generating content regularly even though it may look to users exactly like an ordinary site with static files. Even smaller sites may use tools like Cocoon (discussed in Chapter 19) to manage and generate content for users.

Many sites create customized experiences for their users, making suggestions based on prior visits to the site or information users have provided previously. These sites typically use “cookies,” a mechanism that lets sites store a tiny amount of information on the user’s computer and that the browser will report each time the user visits the site. Cookies may last for a single session, expiring when the user quits the browser, or they may last longer, expiring at some preset date. Cookies raise a number of privacy issues, but are frequently used in applications that interact with users over more than a single transaction. Using mechanisms like this, a web site might in fact generate every page a user sees, customizing the entire site.

Building complex web applications is well beyond the scope of this book, which focuses on the Apache server you would use as their foundation. For more on web-application design in general, see Information ...