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Introduction to Hypermedia Systems

Hypermedia systems encorporate the use of HTML documents to link a series of multimedia pages. These pages can have graphics, video, audio, java applets,flash multimedia and a whole host of other multimedia codecs built into them.

Hypermedia is an acronym which combines the words hypertext and hypermedia.Hypertext is defined as "a database that has active cross-references and allows the reader to "jump" to other parts of the database as required".This definition gives some interesting points about hypertext:(1)

• A hypertext is a database. It is structured and large although the structure is different to that of conventional database systems.


• The typical user action is a jump between parts of the database. Again, this is unlike normal database functionality where the user usuall asks queries an the data that is stored within the database


• The database contains connections between relative pieces of information, thus guideing the user when jumping around through the database

Picture demonstrating hypertext links

The pieces of information, or parts of the database are called nodes. The connections are called links and together they form a hyperdocument. These links are tied to a specific point, word or region within a node. This is defined by the developer. In paper documents there are few links that work as well as hyperlinks. The index within a book is a source of links, however you still have to manually find the page. (3)

A hypermedia system aids the user in exploring the hyperdocument, rather than simply reading it. They allow you to search and query parts or all of the hyperdocument, which cannot be performed on books. A good example of this is an internet search engine such as www.yahoo.co.uk.

A Brief History of Hypermedia

1. 1965 Ted Nelson introduces Xanadu and coins the term hypertext.
2. 1967 Andries van Dam develops the Hypertext Editing System at Brown University.
3. 1978 A team at MIT develops the Aspen Movie Map, the first true example of a multimedia application including videodisk.
4. 1985 Janet Walker develops the Simbolics Document Examiner, the first hypertext system used by "real" customers.
5. 1985 Several other hypermedia systems announced including NoteCards from Xerox.
6. 1986 OWL introduces Guide for the Macintosh, the first widely available hypertext system.
7. 1987 Apple delivers Hpercard free with every Macintosh Computer.
8. 1988 HTML developed at CERN.
9. 1993 HTML development handed over to W3C.
10. 2000 Version 1.0 of XHTML released. W3C announce it will no longer support HTML.

About XHTML

The HyperText Markup Language (HTML) was developed in the late 1980s by Tim-Berners Lee, a particle physicist working for Conseil Européean pour la Recherche Nucléaire (CERN), in Switzerland. This markup language was based on the ISO markup language SGML (standardised general markup language) In 1993, CERN handed over all further development to the World Wide Web Consortium (W3C) who produced version 1.0 of HTML in 1993. This continued to be devloped to version 4.01 in December 1999. (1)

In January 2000, W3C released version 1.0 of XHTML, and announced that it would not be supporting HTML as the standard for the world wide web. XHTML is not based on SGML, but on XML.

XML stands for eXtensible Markup Language and is formed by a much stricter code.

HTML is based on the use of tags. These are keywords surrounded by <angled brackets>, which describe how text and breckets are to be displayed, and to create links to different parts of the document or to other documents. The world wide web is essentially made up of an ever expanding set of interlinked HTML/XHTML documents with the web browsers being used to interpret the coded documents.(2).

References

1. COWDELL JEssential XHTML Springer:2003


2. www.w3c.org Internet reference. Accessed: Feb 2003.


3. BRIDE MTeach Yourself HTML.McGraw Hill: 1998.

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