Language Guide

Introduction

heitml Session Mode allows you to keep track of variable values between pages. This is a superior solution to CGI Scripting Languages, where variables lose their values as soon as a page has been processed. Obviously, Web Applications are much easier to develop when you can gather information from page to page and keep it close at hand while Users visit your Web Site.

heitml Session Mode is designed to work transparently. Every variable of the type se.VariableName is automatically preserved, ready for processing when it is needed.

Session Mode simplifies the programming of a wide variety of applications. You can create a Web Site that allows Users to set up their own preferences. In other words, you can develop applications where Users not only choose the format and appearance of your Site, but perhaps even the content itself. What's more, by maintaining a database of User names and passwords, previous visitors can log onto your Site and instantly be presented with a custom tailored environment to match their own unique needs and tastes.

Imagine a Web Site belonging to your favorite News Organization. Now imagination that you don't have to drill down through multiple menus to find your favorite section (Sports, Politics, Computer News). Maybe you're thinking, "Well, that's what bookmarks are for," but if you're like me and you've gotten to the point where you have four hundred bookmarks organized into a neverending series of folders and sub-folders, or that you are constantly adding to and re-organizing them... Well, pretty soon you begin to wonder why you have to keep track of these bookmarks at all. Why can't your favorite Web Sites do the work for you?

Still not convinced? Then think about that News Organization again and consider what it would be like if the Site not only knew that you wanted to go to Sports, Politics, or Computer News, but that you wanted to see any new article published about heitml since the last time you visited. (Well, OK, maybe a better example would be "any article published about Bill Gates" since your last visit. :-)

But Session Mode's biggest strength lies in the fact that it stores all your program variables in large, self-organizing data structures. No longer do you have to maintain a list of important variables to pass from page to page. No longer do you have to worry about the chance of finding yourself deep into the design of a multi-page application, only to realize that you've forgotten to preserve a much-needed value from an earlier page. With Session Mode, you can create variables at will, on any page where they are needed, and simply forget about them until they are needed again. No matter how far a User wanders from his point of origin, the values he gathers and selects along the way travel with him.

Here are just a few of the things Session Mode makes possible:

• Maintaining a complete session back trace of all pages a user has seen.
• For database search applications: store the complete result of queries in Session Variables and allow the User to scroll through them in a pre-defined sub-window of the Browser display.
• For shopping applications: You can fill a Shopping Kart full of items and, when the User indicates a desire to go to the "Check-out Counter", all price and quantity information is ready to be summarized and submitted for approval. The User can change his mind at the last minute and delete unwanted items, or go back to retrieve items he may have forgotten.

The session mode documentation is structured as follows:

• Basic Session Mode programming
• Session field library simplifies creating forms to show session variables on the screen
• Session trace library handles session traces