Adobe ColdFusion 8 Web Application Construction Kit, Volume 1: Getting Started

Addressing the Web’s Statelessness

The basic building blocks of the Web—TCP/IP, HTTP, and HTML—don’t directly address any notion of a “session” on the Web. Users don’t log in to the Web, nor do they ever log out. So without some additional work, each page visit stands alone, in its own context. Content is requested by the browser, the server responds, and that’s the end of it. No connection is maintained, and the server isn’t notified when the user leaves the site altogether.

Out of the box, HTTP and HTML don’t even provide a way to know who the users are or where they are. As a user moves from page to page in your site—perhaps interacting with things along the way—there’s no way to track their progress or choices along the way. As far as each ...