Data carrier: an introduction to XML

If businesses and public services are to work more effectively by sharing information, they need to be able to share documents carrying that information - and to view them on a wide range of devices. 

A huge effort has been made to create a ‘language’ that allows documents to be shared in this way. This language is XML, and it is vital to both healthcare and Microsoft’s Office 2007 suite. 

The World Wide Web only works because it has a universally accepted language called Hypertext Mark-up Language (HTML). This provides a standard set of rules that allow people to create web pages and services that other people can view from all over the world.

Extensible Mark-up Language (XML) provides a similar, open industry-standard language for organising, storing and exchanging documents and data. It offers the same kind of benefits to businesses and industries that HTML does to the Internet, in terms of enabling them to share and reuse data and documents.


"Regular web users will already be familiar with XML, as it forms the basis of Really Simple Syndication (RSS) feeds - the tool that allows news feeds to be easily incorporated into third party websites"

XML is all around

Regular web users will already be familiar with XML, as it forms the basis of Really Simple Syndication (RSS) feeds - the tool that allows news feeds to be easily incorporated into third party websites. This works because XML allows content - in this case, the news stories - to be separated from their presentation - in this case, the way they appear on the web or in a reader.

One of the great strengths of XML is that it enables this separation of content from presentation. It not only makes data transportable and easy to share, but allows the same data to be displayed on a variety of devices, so that a document can also be read, for instance, on a desktop PC, a PDA or a smart phone.

XML vital for interoperability

XML is absolutely essential in the field of healthcare, where attempts are being made to break away from having data locked up in proprietary IT systems and to allow it to be far more effectively shared and used.

This requires the adoption of common open standards. In the UK public sector, XML has been mandated as a key part of the e-Government Interoperability Framework (e-GiF).

The XML language has also been adopted as the key data and exchange standard for data and messages used by the National Programme for IT in the NHS (NPfIT). It uses the XML language and appropriate health schema in conjunction with HL7v3 to describe content of messages and data.

"XML is a plain-text, meta-language: a language for defining mark-up languages. It is not tied to any programming language, operating system, or software vendor."

Where does XML come from?

Originally developed to support document formats on the web, XML is a plain-text, meta-language: a language for defining mark-up languages. It is not tied to any programming language, operating system, or software vendor.

In a similar fashion to HTML, it makes use of tags for describing document structures. Because XML is a text-based format it is possible to read and edit XML documents using standard text editing tools - you can read an XML message and make sense of it even if you're not a machine!

What are its advantages?

One of the key strengths of XML is its flexibility: it is able to represent both tabular data (such as relational data from a database or spreadsheet) and semi-structured data (such as a Web page or business document).

The extensible aspect of XML also means that it can be tailored to fit the needs of a particular industry or sector. Specific vocabularies, or schema, can and are being defined by sectors such as healthcare and banking.

In the NHS, for instance, schema have been defined and are now in use for the NHS Care Records Service (CRS). XML messages will provide the basis for the CRS, enabling data to be sent easily between different hospital and GP systems to create up-to-date shared summary and detailed care records.

Other key projects within the NHS IT programme that are already using XML include GP2GP record transfers and the messaging behind the Electronic Prescription Service.
"In the NHS, for instance, schema have been defined and are now in use for the NHS Care Records Service (CRS)."
But one of the most significant developments to date has been the switch, since January 2007, from trusts providing data using the old Edifact messaging standard to XML for reporting to the new NHS CRS Secondary Uses Service.

This includes reporting using the Commissioning Data Set (CDS) which provides the basis for payment under Payment by Results. SUS uses XML as its sole data interchange format.

Office 2007 - the next step in XML

Microsoft has been a one of the strongest supporters of XML, which is integral to its Office 2007 product suite. It provides the basis to integrate data between Office products and other services and applications, including those from other suppliers.

Business documents, databases and inter-business communication are all examples of information sources that are moving or have moved to using XML as a representation format. Microsoft products now enable end users and developers to produce and consume documents, network messages and other data as XML.
"Open XML represents an important step towards ensuring that XML achieves its full potential in terms of allowing documents to be archived, restructured, aggregated and re-used in new and dynamic ways."

While earlier versions of Office supported XML, the 2007 Microsoft Office system adopts an XML-based file called Office Open XML Formats.

Any application that supports XML can access and work with data in the new file format. The application does not need to be part of the Microsoft Office system or even a Microsoft product.

Open XML represents an important step towards ensuring that XML achieves its full potential in terms of allowing documents to be archived, restructured, aggregated and re-used in new and dynamic ways.

To help ensure its widest possible use Microsoft is working towards getting Open XML approved as an open international standard.