The Purpose of Meta-HTML

THE META-HTML LANGUAGE REFERENCE MANUAL

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The Purpose of Meta-HTML

HTML is a description layout language. It describes in general the placement and visual style of elements in a page. These elements are generally sequences of text, with an occasional image thrown in for good measure.

Meta-HTML is an interpreted computer language with dynamic variables and flow-control statements. Although it is not a complete general purpose computer language in the traditional sense (i.e., you cannot write a version of a Meta-HTML interpreter in Meta-HTML) it does perform processing and decision making of and on data elements.

A quick example for the impatient is in order. The text:

You are connected to ``metahtml.sourceforge.net'' and reading text written by Brian J. Fox.

is produced in Meta-HTML by:

  <b>You are connected to ``<get-var ENV::SERVER_NAME>'' and
     reading text written by <get-var the-author>.</b>

As the WWW grows, more and more document providers are realizing that stateless connections are only useful for retrieving documents full of static information, and that, at times, it can be very useful to remember state pertaining to the browser that is connecting.

The problem of keeping state for a particular browser user has been resolved by various individuals; all of the solutions require information to be passed back and forth between the browser and the server. For example, to play a WWW Blackjack game could involve the passing back and forth of information including the current wins/losses of the user, which cards have been dealt from the deck so far, and so forth. This information is most often passed to and fro in the form of a "magic" URL. The problems with passing information in this way are two-fold:

The information can be modified by the user before sending it back, which might allow a user to put more money in his or her bank account, for example, and, less importantly,
The URL looks "ugly", since there is a large amount of information present which doesn't describe the essence of the location that the user is connecting to.

Another mechanism can be taken advantage of when both the server and browser being used support HTTP Cookies. While this solves the problem of "ugly" URLs, (this mechanism does not place information in the URL) it generates a new problem: the user must be in possession of a compliant browser, and be communicating with a compliant server. In addition, the information can be changed by the user before sending it back.

Meta-HTML solves the problem of keeping state for a particular session, and it does it in a server and browser independent manner. Our method requires no additional CGI programs to be written. You can read about the technical details in the Session Operators section of this manual.