X marks the sweet spot for Web's future

Dan Brickley reports from Brisbane on the seventh World Wide Web conference

The hassle-free future of communication via the Net became visibly clearer at the recent World Wide Web conference in Brisbane.

This seventh in the series of annual gatherings brought together web developers, programmers, hypertext, multimedia, digital library and standards specialists to discuss latest developments in Web technologies - this year dominated by XML.

More than 100 papers were presented on topics ranging from the social and cultural impact of the Web to algorithms for information retrieval and management. The conference also provides a platform for the World Wide Web Consortium (W3C) to report on its activities during the past year. The W3C is a consortium of industrial and academic organisations, and plays a coordinating role in the development of formal standards for the Web.

In his keynote address Tim Berners-Lee, Web founder and W3C director, spoke about the problem of "evolvability". How can we build a Web in which software does not become obsolete within a matter of months? This alarming pace of change on the Web is of particular concern in the educational sector which does not always have the resources to update browser software every six months. Berners-Lee described the familiar problem of trying to load a version 6.0 document into version 2.0 software: "the software panics - it has met a being from the future! How is it supposed to deal with this unknown document format?" Several of the more recent developments in Web standards address this problem through a move towards "self-describing" documents. The Extensible Markup Language (XML) is the main focus of this work. XML is a computer language for describing document formats for the Web. With XML, user communities can create customised document formats tailored to their own specific needs. XML documents are called "self describing" as they contain enough information to allow word processing and Web browsing software to understand the format, even if that format was invented after the software was produced. The W3C hopes to enable the flexible evolution of document formats on the Web, as well as avoiding the need for a bureaucratic committee process to agree upon each new type of Web document. XML is now established as a W3C recommended technology, and has strong support from Microsoft and Netscape. A number of additional technologies were presented which build upon the foundations provided by XML. Although these are still under development, the features they will offer have now been agreed: lExtensible Style Language will provide a sophisticated style sheet language for XML. XML itself allows user communities to, in effect, define new types of document format in a manner understandable by software. XSL adds to this by providing a language for saying how those documents should be displayed, printed or even pronounced.

lXML Linking Language, together with the XML Pointer Language (Xpointer) offers a richer set of mechanisms for creating links between Web resources. Xpointer will make it possible to create hypertext links to any part of a Web page. This will allow more accurate references: a link could be made to the third item in a list in the second paragraph of a page, for example. The XLink specification, when completed, will be more far reaching. XLink will allow hyperlink information to be stored externally from the document being linked from. This is a radical change for the Web and opens up a number of possibilities for creating new kinds of teaching and learning materials. For example, multiple "link databases" could be created that work alongside electronic texts, providing hyperlinks into glossary, quiz or explanatory material. As the linking information can be managed separately from the main text, a single primary resource, Hamlet, for example, could be presented to users in a number of ways. First-year students might see a document annotated with links to a Shakespeare glossary; PhD researchers would see the text as containing hyperlinks to related scholarly works.

lDynamic HTML or DHTML has received a lot of coverage since both Netscape and Microsoft advertised dynamic HTML facilities in the last versions of their browsers. DHTML is a largely a marketing term used to describe the ability of a page to change its appearance dynamically, in response to user actions. DHTML will allow the creation of Web pages that contain images and text that move, change colour, appear and disappear. The W3C is standardising a framework which will cover DHTML as well as improved navigation facilities. This is the DOM, or Document Object Model. As with XML, there are commitments from all major software providers to produce DOM-compliant Web authoring and browsing tools when the standard is complete. Web authors should take note that DOM tools will only work reliably with pages that contain valid HTML. Similar problems may arise with the new XML linking systems. So although these new technologies are not yet available, it is possible to plan for their arrival by using HTML validators http://validator.w3.org/), for example.

Dan Brickley is a researcher in the Institute for Learning and Research Technology, University of Bristol.