2. TECHNICAL ASPECTS OF THE WWW, THE INTEGRATOR OF "CYBERSPACE"

2-1 The HTML Mark-Up Language

The standard WWW information vehicle is a hypertext document, an text file encoded with the so-called "Hypertext Mark-Up Language" (HTML). An HTML file will display on your screen according to special mark-up commands and according to the possibilities of your client-program. Special high-lighted buttons in a displayed "page" allow retrieval of other pages from anywhere in the world (including any kind of file formats that your set-up can handle). When a file format is accessed that the browser does not understand (e.g. a Postscript file), a "helper" software is called, if it is available on your machine. This explains that you can configure your client to use any kind of program to display any multimedia image, sound, video and data format. Note also, that most WWW clients can display in-line images in GIF format.

Short of being able to discuss the HTML mark-up language in length, let's examine a simple example of a WWW "page" demonstrating its syntax:

<HTML>
<HEAD>
<TITLE>Title (Name) of this html page</TITLE>
</HEAD>

<BODY>
<H1>Big Title</H1>
<H2>Title 2</H2>Here is a list:  
<UL>  
  <LI> element 1
  <LI> element 2
</UL>
This is an enumerated list:
<OL>    
  <LI> element 1    
  <LI> element 2   
</OL>
This is a simple paragraph. Text will be formatted.
<A HREF="http://tecfa.unige.ch/info-www.html">Click HERE </a> to learn more about the World-Wide Web.<p> Here is a preformatted paragraph:
<pre>     
This is a simple paragraph. Text will not be formatted.
This is a simple paragraph. Text will not be formatted.
</pre>  
<A HREF="http://tecfa.unige.ch/tecfa/general/tecfa-people/schneider.html">D.S.</A>
</BODY>
</HTML>

                                Title (Name) of this html page
                  BIG TITLE
Title 2

   Here is a list:
	     * element 1
	     * element 2

   This is an enumerated list:
	    1. element 1
	    2. element 2

This is a simple paragraph. Text will be formatted. Click HERE to learn more about the World-Wide Web.
Here is a preformatted paragraph: 
This is a simple paragraph. Text will not be formatted.
This is a simple paragraph. Text will not be formatted.

D.S.
Figure 2: Sample Output using a line browser

HTML is an extension of the SGML language which is widely used in the editing industry for describing the logical structure of a document. An HTML element normally is delimited by tags: "<tag_name> text </tag_name>". A tag may include a name, some attributes and some text or hypertext. For example: "<TITLE>Title (Name) of this html page</TITLE>" specifies the name of a page. An HTML document is composed of a single element: "<html>...</html>" that is, in turn, composed of head and body elements: "<head>...</head>" and "<body>... </body>". Text displayed in a browser is part of the body and its structure is defined by tags like "<h1> . . . </h1>" (prominent header), "<p>" (paragraphs) or "<ul> <li> First item in the list, <li> Next item in the list, ...</ul>" (unordered lists). There are several kinds of hypertext links. Its simplest form is: "<A HREF="Universal Resource Locator">D.S.</A>" ("D.S" will display as a hypertext button). The HTML page in the example above will display with a simple line browser (like "Lynx") as shown in figure 2.There are several ways of producing HTML pages:

Using a simple text editor and inserting html tags manually;
Using a "smart" text editor (like Emacs) or an "HTML tool" (like HotMetal) which inserts the necessary HTML tags via menus or hot keys;
Using "filters", i.e. translation programs that translate from text processing or other formats into HTML;
Using programs that create HTML "on the fly", a feature frequently used to display output resulting from a data base request.

Each of these methods has its advantages. All of them are well described in the introductory literature available on the Network.

Learntec 94 Article - 13 FEB 95

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