XML for beginners

XML is the latest buzzword in e-business technology. Danny Bradbury explains how it is set to make Web data smart enough for...

XML is the latest buzzword in e-business technology. Danny Bradbury explains how it is set to make Web data smart enough for business

What is XML? XML stands for eXtensible Markup Language. It developed as a subset of the Standard Generalised Markup Language (SGML). It has gained prevalence in the last 18 months thanks to companies like IBM, which have pushed it as a standard.

Why is it important? On its own, XML is pretty much useless to the average IT department. This is because XML is as wide as data itself, and is too nebulous to be useful. Instead, the importance of XML is as a language for defining other Web languages. In HTML you can use specific tags to give instructions about the way that a Web page will look. With XML, you can define your own tags that enable your software to tell other pieces of software what a particular piece of data means, and what should be done with it.

This makes it particularly relevant in a business-to-business e-commerce context, because companies can use XML-based messages to send messages to other firms' computers that are particularly relevant to their business. An XML language is defined in something called a Document Type Definition (DTD). DTDs are under development for many different vertical markets, and the types of tags used for, say, a DTD in the shipping and distribution industry will differ from those in a DTD for the legal profession, or for the medical world, for example.

XML messages can also be used to send data about their own tags, so that an XML-savvy application at the receiving end can read the message and understand what is to be done with the data, even if it has little information about the contents of the message beforehand. What this means in practice is that you can code both processes and data into an XML message, to a certain extent. However, do this with care, as you could find yourself putting a big communications overhead on top of your application data.

Who looks after standards issues? The World Wide Web consortium (W3C) has standardised XML as a language for use on the Internet.

How does Microsoft's Biztalk fit in? The first thing to remember is that you don't need Biztalk to make XML work. Microsoft developed its Biztalk server (which is still not shipping and is very late) as a means of exchanging e-commerce information between servers. The independent Biztalk movement has been set up to define XML-based schemas for vertical market applications, but there are many other schemas.

How many people are using it? Few people are actually using XML in anger because it is such a new technology. The main drive, as always, has come from the supplier community, where companies are using it as the latest buzzword to increase sales. The truth is that, as always, the customer community will be a couple of years behind, and you're unlikely to see it being used in force until 2002-3.

The main impetus behind XML is as an integration language, and so a lot of enterprise resource planning suppliers have announced support for it, as have the enterprise application integration suppliers - those companies selling "hub" software to take data from various applications and translate them for other applications to read. Expect to see significant amounts of activity in the electronic procurement area.

Is it the only answer for e-business? Certainly not, in spite of what some suppliers may tell you. In fact, right now it's probably not the best route to take because it is still relatively immature. There are other solutions for business-to-business e-commerce, such as the increasing number of online business-to-business marketplaces. Check out places like CommerceOne and Ariba for more information on these. Some of these marketplaces are offering XML support, but not all of them require you to use XML.

Where can I find out more information? Check out www.XML.org for information about what's going on in the XML world. You can also try www.biztalk.org for details about the ongoing Biztalk developments. And don't forget www.w3c.org for the latest on XML standardisation.

What are the staffing issues? At present, there are few people with a clear enough idea of XML and how to use it. Much e-business software offers XML support, but it's unlikely to be a plug-and-play operation. If you go down this route, you need someone to take your e-business application and map it onto an XML schema for you, which could be tricky. If you can find someone competent enough to do this for you - and that's a big if - then you'll probably be paying through the nose.

BASDA and XML

Many groups have been working to create specific vertical market DTDs and schemas that work with XML, but the Business and Accounting Software Developer's Association (BASDA) has taken a different approach. Last summer, it announced a set of schemas designed for more horizontal XML-related communications between accountancy software packages, under the umbrella name eBis-XML. Over 50 different software suppliers have agreed to support the schema. In December, the organisation published the first versions of its Order and Invoice Specification. Dennis Keeling, head of the association, says that more specifications will complement the schema at a later date.

Additional Standards associated with XML

The W3C has been working on other standards that are related to XML, some of which are complete and some that still need to be ratified. These standards will help developers to make their XML programs and documents more functional, and they include:

XML-Dsig - a standard for providing digital signatures that can be used to verify XML documents.

Extensible Stylesheet Language (XSL) - This is a language for designing stylesheets within XML that can be used to define the presentation of lots of XML documents at once.

Resource Description Framework (RDF) - This standard describes how XML can be used to link information about lots of different Web resources together. Such resources can include site maps, content ratings and search engine data collection.

XML Linking Language (Xlink) - this allows elements to be inserted into XML documents that link the documents together.

XML Base - Lets developers define a base URL within an XML document that is always the same regardless of other URLs. It will be used in conjunction with XLink.

XML Query - Defines terms that can be used to query XML documents.

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