Aestiva H2O Web Site

Installation:
  Free Downloads
  The H2O Family
  Install Notes

Programming:
  Prerequisites
  H2O Whitepaper
  Online Manual
  Code Examples
  H2O Free Support

What's H2O?
H2O is programming made for the web.

What's it like?
H2O is English-like. If you know some Perl, VB, ASP, or PhP you'll be immediately productive in H2O. It runs on Linux, Mac, Unix, and Windows.

How do I try it?
Download H2O for free. Get it from hosting providers. Or buy on-line.

Where does H2O come from?
The language was invented by Aestiva. H2O stands for:
   HTML with
   HTML/OS
   Overlays.

H2O Prerequisites

Ever wonder why writing programs that run in browsers is so darn complicated? We did too. After all, advanced web sites are just "web pages on-the-fly." So it shouldn't be so hard. That's why Aestiva invented H2O.

H2O is easy to learn. It's programming without all that unnecessary complexity.

H2O is appropriate for programmers at any level, as well as web designers, business owners and people who don't make programming their profession.

Having said that, the question is, What does one need to know to use H2O? Here's a list:

Knowledge of HTML.
At the very least you should know or be willing to learn how to write HTML Tables, Hypertext Links, Fonts and HTML elements.
Knowledge of Scripting.
At the very least you should know or be willing to learn how to write lines of code containing variables, IF-THEN statements, loops and file names.
Knowledge of Arrays.
At the very least you should know or be willing to think about information organized in two-dimensional tables (grids with one or more columns and rows).

If you're fine on these three points then read on.

Okay, so let's learn how to use H2O

Programming H2O is about putting little programming macros in HTML documents. Once you know that, you'll know the basics of H2O.

Here are the rules. Read carefully.

In H2O your programming is placed within << and >> brackets. Inside these brackets is H2O. Outside is HTML.

These small programs are called Overlays. Remember this word - Overlay (repeat three times). You can place these Overlays anywhere you want in your document. For example, placing <<DISPLAY TODAY /DISPLAY>> in a document injects today's date at that point in the document.

HTML Input Forms and Links can run Overlays too. In H2O links can point to other HTML documents like normal HTML. However, in H2O links can also point to Overlays placed at the bottom of the document. These Overlays are called On-click Overlays.

When a person clicks a link or an HTML form that points to an On-click Overlay, the instructions in that Overlay are run. Once the instructions are run, an instruction like GOTO "somepage.html" redirects the user to the page actually displayed.

Okay, so let's look at an example

<HTML>
<HEAD>
<TITLE>Sample Page</TITLE>

</HEAD>
<FORM METHOD=POST ACTION=test_password>
Enter Password:
<INPUT NAME=mypassword TYPE=PASSWORD SIZE=20>
<INPUT TYPE=SUBMIT VALUE="Login">
</FORM>
</HTML>
<<OVERLAY test_password

IF mypassword="Please" THEN
GOTO "entry.html"
ELSE
GOTO PAGE
/IF
>>

The code displayed in black is regular HTML. The green stuff is H2O. Note how the HTML form is linked to the On-click Overlay called test-password. When the user clicks the submit button the Overlay is run. The Overlay tests to see if the value of mypassword equals "Please". If it doesn't the page is redisplayed (PAGE means the current page). If mypassword equals "Please" then the page "entry.html" is displayed.

Summary
H2O is about commands you place in HTML documents. Once you learn the H2O language you'll know how to change web pages "on-the-fly" and work with data placed in HTML forms. Since this is the essence of web construction, once you learn that you'll have what it takes to build sophisticated web sites.

As a next step we recommend you read the book Advanced Web Sites Made Easy. The book is designed for non-professionals interested in learning H2O or HTML/OS (Both versions of H2O use the same language).