A new web programming language is transforming the business-to-consumer market. We explain why XML will change the way you do business too
Imagine that you are a Madonna fan. You wish to purchase her CD "Music" online. You first turn to your favourite search engine, Google (www.google.com), and enter "Madonna", "CD" and "Music" as keywords. Not bad, but as with most searches you need to sort out the relevant sites from the (very) irrelevant.

You have an alternative, however. You log onto Kelkoo (www.kelkoo.co.uk) and go to the "comparison" section for music and specify what you want. Within seconds you are told about nine websites that supply the CD by post, complete with current pricing.

Comparison engines
Comparison engines like Kelkoo work by searching the online databases of numerous suppliers. They can do this for a wide range of products (books, videos, cars) because these items are well defined by comparatively simple search terms. Now imagine how much more useful the internet would be if the same applied to business use – if, for example, any item needed in a construction project could be located, with pricing, from all suppliers automatically.

At some point in the not-too-distant future that is precisely what we will be able to do – the result of a major step forward in how the internet works . The name of this development, eXtensible Markup Language (XML), is hardly memorable. Then again, many people already use HTML (HyperText Markup Language), currently the basic language of the internet.

HTML commands tell your web browser how to lay out information from a web page on your screen. It defines new paragraphs, the size and colour of text, and the use of bold or italics. It consists of a series of instruction called "tags" which occur in pairs. For example, say we wanted to print "Red sky at night" with one word in red. In HTML this shows as follows:

<font color="red">"Red"</font> sky at night

The problem with HTML is that it deals only with how information appears on the page. However, when we view or are sent a document it is what the words actually mean that matters. As humans we are very good at interpreting the meaning of pages of text. But computers need structure, and if we are ever to automate the routine tasks involved in communicating between companies, we need to address this issue.

It would help if everybody involved in the supply chain had a common way of referring to all of those things they deal with every day. The International Alliance for Interoperability (IAI) was formed many years ago by major players in the construction and facilities management industries. Its aim was to specify how both real objects (eg doors, windows etc) and related concepts (eg projects, prices etc) could be represented electronically. The solution was a range of Industry Foundation Classes where each class described a set of items that shared common characteristics.

In simple terms, where HTML describes how a word should look on the page, XML describes what it is

Enter XML in February 1998 as a publishing and document interchange format sponsored by the World Wide Web Consortium (W3C, a "hidden" force behind the internet). Information held in XML format is often termed "self-describing". In simple terms, where HTML describes how a word should look on the page, XML describes what it is, for example:

<chair>reclining lounger</chair>.

So if you search for chair, the above entry would be found, even though it is called a reclining lounger. This is because it is classified by the tags as a chair.

XML for construction
A web-friendly computer format capable of describing data is, of course, only a first step. W3C only defined how the XML system worked in principle. It didn't define which words should be used to describe which items. If I describe a "PC" but you want to call it a "computer" then we will still fail to communicate effectively.

This next step is to provide a "schema" specific to the construction industry. Groups involved in this effort met in London late last year, and work to agree an overall standard continues.

Why, then, is any of the above relevant to anyone who does not have an IT role? To understand this, go back to Kelkoo. When services like Kelkoo started, there was a lot of resistance from online retailers who wanted customers to visit their sites directly. But customers realised that a CD was identical whoever supplied it, and that what really mattered was price. They started using comparison sites instead of visiting retailers directly. Retailers who had refused to co-operate found that business was being lost to those who did.