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21. HEITML server side extension of HTML and a 4GL language for PostgreSQL

Tool heitml is another way to interface postgres with the world wide web. For more details contact

          Helmut Emmelmann H.E.I. Informationssyteme GmbH 
          Wimpfenerstrasse 23 Tel. 49-621-795141 
          68259 Mannheim Germany Fax. 49-621-795161 

heitml is a server side extension of HTML and a 4GL language at the same time. People can write web applications in the HTML style by using new HTML-like tags.

heitml (pronounced "Hi"-TML) is an extension of HTML and a full-featured 4th generation language that enables Web-based Applications to interact with data stored in SQL databases, without resorting to complex CGI scripts.

heitml extends HTML on the sever side, dynamically converting ".hei" files to HTML format and so is compatible with any web browser.It embraces the familiar, easy-to-use HTML syntax and provides a large assortment of pre-developed Tags and Libraries to take care of tasks that formerly required CGI. As XML, heitml provides user defined tags. With heitml the user defined markup can be translated to HTML and send to a browser.

heitml targets both HTML designers and professional programmers alike. HTML designers can use heitml Tags to build dynamic web pages, access SQL databases, or create complete web applications. Counters, registration databases, search forms, email forms, or hierarchical menues can all be created simply by using the pre-developed HTML-like Tags found in the many Component Libraries.

For programmers heitml embeds a complete forth generation language in HTML

          (e.g. <if>, <while>, and <let> Tags), 
plus powerful expression evaluation with integer, real, boolean, string, and tuple data types. Tuples have reference semantics as in modern object oriented languages and are stored on a heap. heitml variables including all complex data structures stored on the heap maintain their values between pages using the Session Mode. It is possible to define your own tags or environment tags and even re-define HTML-tags.

heitml makes it possible to

- - - develop Web Sites in a structured and modular way, drastically reducing maintenance overhead.

- - - develop intelligent and interactive Web Sites, with content that dynamically adapts itself to user needs.

- - - show the content of SQL databases with no programming other than to use our library of prefined "dba" Tags.

- - - develop complex database and Catalog Shopping applications using Session Variables

heitml runs on Linux with any Web Server using the CGI interface, and is especially fast (avoiding the CGI overhead) within the APACHE (version 1.1.1, 1.1.3, or 1.2.4) Web Server using the apache API. Currently MSQL (Version 1 and 2), PostgreSQL (Version 6), mysql, and the yard databases are supported). heitml also works on Linux, BSDi, Solaris and SunOS, as well as Windows NT with CGI and ISAPI and ODBC and Windows 95.

heitml (on linux) is free for research, non-commercial and private usage. Commercial Web Sites must pay a licensing fee. The fully operational version of heitml is available for a trial period downloaded freely. (Note, however, that each ".hei" Web Page you develop will display a message identifying it as the version for non-commercial use. After registration, you will receive a key to switch off the message without having to re-install the program.)

New features in version 1.2 are

- - - Component Libraries for Database Search Forms, opening and closing hierachical menus, and email forms

- - - Session Mode has been re-designed and enhanced to keep all variables (including the entire heap) between pages. This means data of any size can be kept within a session. This opens up the opportunity for a wider range of new applications, e.g. storing complete query results in session memory.

- - - Installation instructions, documentation and example libraries have been significantly improved, a Tutorial has been added

- - - Tags to execute shell commands and send emails have been added

- - - Pretty Printing and debugging support. heitml shows your source code in color in your browser and marks errors in an intuitive way. In the case of runtime errors, all internal data structures are displayed in the browser marking and preserving the original source code positions.

- - - Various new server variables and built-in functions have been added

- - - In production mode heitml now collects complete information on errors that occurred while people were accessing your site.

This is what the home page of the heitml says -

heitml (pronounced "Hi"-TML) significantly extends and enhances the functionality of HTML by definable tags and full programming features. This makes dynamic content and database applications possible simply within the HTML world, without CGI and without external scripting or programming languages. This means you, as an HTML author, can embed applications in your web pages, simply by using some new tags without CGI and without programming. As an advanced user or programmer on the other hand you can create and program powerful tag libraries. This approach makes heitml suitable for HTML newcomers and professional programmers alike. heitml runs on the web server and dynamically generates HTML, so heitml is compatible with the internet standards and with any web browser. It allows full access to databases while shielding the user from any unneccessary CGI complexity. heitml has been developed according to the newst research and in compiler construction and transaction systems.

heitml pages are developed just the same way as HTML pages, with a text editor or HTML editor, and placed on the web server as usual. However now pages can contain dynamic heitml tags and access tag libraries. You can use these tags to access the database, to create dynamic content, to send emails, and even to create powerful applications like registration databases and shopping systems.

HTML newcomers and professional programmers alike will be amazed at how quickly and easily they can design exciting applications like our Interactive Guestbook without resorting to complex and difficult to learn CGI scripts, simply by using the tools provided in our dba Library.

heitml is accompanied by a wide range of tag libraries, to create guestbooks, database maintenance applications, extensible query forms, powerful email forms or structure your web site using a hierarchic menu. These tools are ready to go, just add the corresponding tags to your web site.

As an experienced programmer you can make fully use of the heitml persistent dynamic tuple architecture : heitml is not just a scripting language with dynamic typing, full power expression evaluation, recursive procedures and extensive parameter passing features, but it also features persistent dynamic tuples to automatically keep session data of any size.

heitml has so many features and uses it is impossible to describe it in a single Web Page. For that reason we have set up this Web Site in a manner that allows you to obtain a simple product "overview", or to delve as deeply as you want into the "nuts and bolts" of the language. Whichever manner you choose, we think you'll find that heitml has a lot to offer, and we hope you'll agree that it truly "takes the World Wide Web to a Higher Level!"

The menu on the left-hand side of the screen will help you navigate our Web Site in an organized and methodical manner, but you can also use our Quick Menu to instantly jump to any page with a single mouse-click.

If you're a first-time visitor to this Site, we suggest that you check out the heitml Interactive Guestbook for a truly impressive demonstration of how heitml can make your Web Pages more Interactive. If you sign our Guestbook, you can leave comments or tell us about your favorite Web Site using HTML formatting commands. It's like creating your own private Web Page and seeing it published immediately!

The heitml Features section provides a Quick Summary of Features and Benefits, as well as Pages that are tailored to address the specific needs and questions of Designers and Programmers Our Language Guide provides an on-line tutorial that demonstrates in a practical manner some of the ways you can use heitml to develop, enhance and simplify your Web Pages and Applications.

The Language Reference is for those looking for specific information regarding the syntax, structure and use of the various language elements. However, it would be a good idea for everyone to read the General Design page, which provides an overview of the specific kinds of problems heitml is designed to solve.

Naturally, you'll want to know whether heitml runs on the specifc Operating System, Web Server, or SQL database software you're currently using, and you'll find all that information in our Supported Platforms section.

Finally, we invite you to Download a trial copy of the program for use on your own system. We know you'll appreciate this "try before you buy policy", and we look forward to any feedback you'd like to give us.

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