Interactive Pages by Keith Oustalet
Many of today's Web Sites generate their content from information stored in SQL Databases. If you've ever used one of the popular Search Engines, like Yahoo or Alta Vista, you've probably been amazed to discover how much information they contain. So much, in fact, that all but the most targeted and selective searches often return hundreds, if not thousands of references to Web Pages. We obviously have neither the time nor the bandwidth to wait for so much information to be downloaded into our Browsers, and even if we did, the resulting Web Page would be so large as to be overwhelming.
For this reason, methods have evolved to manage such data, and to break it up into smaller chunks, often no more than 10 or 20 line items per page.
While your own Web Site may pale in comparison to the amount of information stored in the Search Engines, even a simple Guestbook can grow to be quite large, and suffer greatly if you don't have access to the tools required to manage it. Once again, heitml has anticipated your needs by developing libraries that help you with these chores. Although the type and variety of information stored in databases varies enormously, any Web Site that uses a database will likely encounter many of the same problems.
First, and foremost, we need a method to add new records to our databases, as well as a way to update existing records, or delete them when they are no longer useful. In this respect standard HTML falls short of our needs, for although HTML provides us with a <FORM> Tag to facilitate User input, it lacks a mechanism for processing that input once it has been submitted.
Prior to the development of heitml a large number of Scripting Languages arose to fill this lack, the most popular of which has been PERL. In many ways Scripting Languages have done an admirable job of handling these "behind the scenes" processing tasks, but two of their most often heard criticisms have been their somewhat cumbersome syntactic conventions, and the security problems they pose to System Administrators. A non-HTML-like Syntax causes headaches for programmers, as it is easy to make an error, yet difficult to find and correct them. And from the security standpoint, a language that allows access to Operating System functions means that any Web Page using a Script can not be placed into production until it has passed through a screening process, often resulting in lengthy delays, not to mention the cost of assigning expensive personnel to such tasks.
heitml suffers from neither of these drawbacks. It employs the same User-friendly Syntax as HTML and, except for the special-purpose shell Tag, which can easily be turned off at the system level, offers no chance to interfere with other processes, or to access or erase files which do not belong to it.
The second most common requirement of Web Site databases is that Users must have a way to tell the database what they are looking for. In short, they need their own mini-search engine, a way to construct and execute SQL Queries, without requiring the User to have any knowledge of SQL.
To fulfill this requirement, we have developed Database Search Components, a collection of components that will prove invaluable, especially in view of the fact that even a casual HTML Page Designer can use them, without himself having any knowledge of SQL.
Once a Query has been submitted to the database, the next problem is how to manage and display the information returned by the Query. To this task comes the Database Display and Scrolling Components, a collection of components that allows the Page Designer complete control over the number of items or records to be displayed on a page, as well as their formatting.
Last, but not least, there are times when FORMs impose limitations on communication that outweigh the advantage of storing the data in a database. Many Web Sites allow Users to "leave a message" for someone by filling out a FORM, but unless the User is quick-witted enough to print or save a copy of what he has written, he has no record for himself, and no easy way to keep track of whether or not a response has been made.
With heitml's Mailform Application Component, however, a FORM can be designed that not only writes to a database, but mails the message directly to one or more email addresses, also giving the User the option of sending a copy to himself.
All of these tasks will be discussed in detail in the sub-pages in this section. However, there is one additional component that can be used by Database Administrators to write Web-based Database Management Applications that update records of a Database relation.
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