Friday, September 19, 2003

Why XML?

Lee's comment: Unrelated to all things BU, what does an XML feed DO, exactly?

Answer: XML provides a platform-independent marked-up document. That's exactly the same as HTML, except that XML is more extensible. In fact, that's what it stands for - eXtensible Markup Language (HTML == HyperText Markup Language). HTML is designed specifically to markup hypertext - when you put a tag like < strong > around some text, it becomes marked-up hypertext that your browser interprets as needing a bold font for display. XML is extensible - which means you can define your own tags, which HTML doesn't allow you to do. There is a well known set of tags in an XML scheme called RSS (Really Simple Syndication) which anyone can use to syndicate their weblog or other serialized publishing.

So why is that a good thing? Well suppose you are short-sighted and like viewing text in a really big font. XML syndication via the RSS schema lets you use a program that understands RSS to grab my xml feed, which contains just the data without all of the style choices I made, and redisplay it with a really big font. Or in the color red. Or however you like.

RSS feeds also contain a timestamp - so if you want, you can get a program called an aggregator which gets the XML feed for all of your favorite blogs, updates them every 5 minutes, and shows you all of them on one page. No more remembering 50 blog links - just enter them once into an aggregator, and you'll never miss an article again. Advanced aggregators let you customize how blogs appear, whether to categorize based on origin, title, date, etc. They're neat tools.

In fact, I wouldn't be surprised if BlogSpot saves my post as an XML document, and passes my post and my display template to an XML transformer which turns it into HTML automagically. It would be an easy way to automate their hosting process.

So why am I providing an XML feed? A) I'm a computer geek and B) It provides a self-marking document which allows anyone to display the data anywhere without having to scrape my weblog page or remove all the HTML crap they don't want.

To try a good RSS aggregator, try

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