Real-World XML

Hopefully by now you understand some of the reasons XML came into being, as well as how it will likely fit in with HTML as the future of the web unfolds. What I haven't explained yet is how XML is impacting the real world with new markup languages. Fortunately, a lot of work has been done to make XML a technology that you can put to work immediately, and there are numerous XML-related technologies that are being introduced as I write this. Following is a list of some of the major XML-based languages that are supported either on the web or in major XML-based applications, along with the kinds of information they represent:

  • WML (Wireless Markup Language) Web pages for mobile devices

  • OFX (Open Financial Exchange) Financial information (electronic funds transfer, for example)

  • RDF (Resource Description Framework) Descriptions of information in web pages

  • RSS (Really Simple Syndication) Syndicated web site updates (news feeds and blog entries, for example)

  • MathML (Mathematical Markup Language) Mathematical symbols and formulas

  • OeB (Open eBook) Electronic books

  • OpenDocument Open file format for office applications (word processing, spreadsheet, and so on)

  • OWL (Web Ontology Language) Semantic web pages (an extension of RDF)

  • P3P (Platform for Privacy Preferences) Web privacy policies

  • SOAP (originally Simple Object Access Protocol) Distributed application communication

  • SVG (Scalable Vector Graphics) Vector graphics

  • SMIL (Synchronized Multimedia Integration Language) Multimedia presentations

  • UDDI (Universal Description, Discovery, and Integration) Business registries

  • WSDL (Web Services Description Language) Web services

  • XAML (eXtensible Application Markup Language) Graphical user interfaces (used by Microsoft in the new version of Windows, codenamed Longhorn)

  • XBRL (eXtensible Business Reporting Language) Business and financial data

I told you earlier that XML people love acronyms! And as the brief descriptions of each language suggest, these XML languages are as varied as their acronyms. A few of these languages are supported in the latest web browsers, and the remaining languages have special applications that can be used to create and share data in each respective format. To give you an idea regarding how these languages are impacting the real world, consider the fact that the next major release of the Windows operating system, codenamed Longhorn, is using XAML (pronounced "zammel") throughout to describe its user interfaces in XML. Additionally, Microsoft and Intuit have invested heavily in OFX (Open Financial eXchange) as the future of electronic financial transactions. OFX is already supported by more than 2,000 banks and brokerages, in addition to payroll-processing companies. In other words, your paycheck may already depend on XML!

By the Way

Another interesting usage of an XML language is SVG, which is used to code plats for real estate. A plat is an overhead map that shows how property is divided. Plats play an important role in determining divisions of land for ownership (and taxation) purposes and comprise the tax maps that are managed by the property tax assessor's office in each county in the U.S. SVG is actually much more broad than just real estate plats and allows you to create virtually any vector graphics in XML. You learn more about SVG in Tutorial 6, "Using SVG to Draw Scalable Graphics."

I could go on and on about how different XML languages are infiltrating the real world, but I think you get the idea. More specifically, Tutorial 23, "Going Wireless with WML and XHTML Mobile," shows you how to code web pages for mobile devices, while Tutorial 24, "Syndicating the Web with News Feeds via RSS," shows you how to use the RSS language to efficiently stay up to date with your favorite web sites.

By the Way

As more evidence of the importance that major technology players have placed on XML, consider the fact that Microsoft's .NET development platform is based entirely upon XML.