My 5/10/09 Missoulian column
Last week I described XML – extensible markup language – and how it is the backbone of RSS news feeds.
XML is a language used to “markup” data and information for access by other languages and computers, and is used for much more than just news feeds. One of the most important uses for XML is combining it with other languages to present information on the Web and exchange information with other computers in a standardized format.
XML allows the same data and information to be accessed and presented in different ways across many platforms, allowing all kinds of interactions between computers and computer languages.
If you looked at the raw code of a music playlist in an MP3 player, you’d see XML. The Federal government recently began releasing congressional voting records and other information in XML, and the new push to go electronic with medical records will rely on XML.
One important example involves another acronym: HTML, the language of Web pages. HTML is also a markup language – hyper text markup language – and so it “marks up” and describes how Web pages should look.
As I’ve described, XML is purely for data, but HTML is the language that provides the presentation of that data. XML and HTML are used together in a way that is much faster and more efficient than in the “bad old days” before XML. HTML handles the Web presentation and XML the data, and that combination is accessible across all Web browsers.
Another important difference between HTML and XML is how they are standardized as languages. HTML has a standard grammar that is set by groups of computer organizations and academics; in other words, you can’t make up your own “markup” in HTML and expect it to work on everyone’s Web pages.
With XML, you can make up your own descriptors (with some limitations) to “markup” your data, and when other people use those descriptors, they can get your data in exactly the same format you want them to get it in.
That’s where the “extensible” of XML comes in, and extensibility is very important as many different forms and sources of information move to the Internet and need to be presented and accessible for different computers and applications.
And, an interesting newer “extension” of XML itself is called XBRL, or extensible business reporting language. That’s for next week.