This article is an excerpt from the ExtremeTech book Hacking
RSS and Atom. This feature explains what
RSS and Atom
feeds are and how you can build an aggregator, route
feeds to your inbox and buddy list, subsribe to multimedia content, and more.
What are RSS and Atom feeds? If you're reading this, then it's pretty likely you've already seen links to feeds (things such as "Syndicate this Site" or the ubiquitous orange-and-white "RSS" buttons) starting to pop up on all of your favorite sites. In fact, you might already have secured a feed reader or aggregator and stopped visiting most of your favorite sites in person. The bookmarks in your browser have started gathering dust since you stopped clicking through them every day. And, if you're like some feed addicts, you're keeping track of what's new from more Web sites and news sources than you ever have before, or even thought possible.
If you're a voracious infovore like me and this story doesn't sound familiar, then you're in for a treat. RSS and Atom feedscollectively known as syndication feedsare behind one of the biggest changes to sweep across the Web since the invention of the personal home page. These syndication feeds make it easy for machines to surf the Web, so you don't have to.
So far, syndication feed readers won't actually read or intelligently digest content on the Web for you, but they will let you know when there's something new to peruse and can collect it in an inbox, like email.
In fact, these feeds and their readers layer the Web with features not altogether different than email newsletters and Usenet newsgroups, but with much more control over what you receive and none of the spam. With the time you used to spend browsing through bookmarked sites checking for updates, you can now just get straight to reading new stuff presented directly. It's almost like someone is publishing a newspaper tailored just for you.
From the publishing side of things, when you serve up your messages and content using syndication feeds, you make it so much easier for someone to keep track of your updatesand so much more likely that they will stay in touch since, once someone has subscribed to your feed, it's practically effortless to stay tuned in. As long as you keep pushing out things worthy of an audience's attention, syndication feeds make it easier to slip into their busy schedules and stay there.
Furthermore, the way syndication feeds slice the Web up into timely capsules of microcontent allows you to manipulate, filter, and remix streams of fluid online content in a way never seen before. With the right tools, you can work toward applications that help more cleverly digest content and sift through the firehose of information available. You can gather resources and collectively republish, acting as the editorial newsmaster of your own personal news wire. You can train learning machines to filter for items that match your interests. And, the possibilities offered by syndication will only expand as new kinds of information and new types of media are carried and referenced by feed items.
But that's enough gushing about syndication feeds. Let's get to work figuring out what these things are, under the hood, and how you can actually do some of the things promised earlier. Continued...
If you're already familiar with all the basics of RSS and Atom feeds, you can skip ahead to the section, "Gathering Tools," later in this feature. But, just in case you need to be brought up to speed, we can take a quick tour of feed consumers, feed producers, and the basics of feed anatomy.
Catching Up with Feed Readers and Aggregators
One of the easiest places to start with an introduction to syndication feeds is with feed aggregators and readers, since the most visible results of feeds start there. Though you will be building your own aggregator soon enough, having some notion of what sorts of things other working aggregators do can certainly give you some ideas. It also helps to have other aggregators around as a source of comparison once you start creating some feeds.
For the most part, you'll find feed readers fall into categories such as the following:
Desktop newscasts, headline tickers, and screensavers
Personalized portals
Mixed reverse-chronological aggregators
Three-pane aggregators
Though you're sure to find many more shapes and forms of feed readers, these make a good starting pointand going through them, I can show you a bit of the evolution of feed aggregators from heavily commercial and centralized apps to more personal desktop tools.
Author: Leslie Orchard
Previous article: 09 September 2006
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