Discovering Feeds | What Are Syndication Feeds

Returning to the beginning of this article, those links or buttons labeled Atom, RSS, or XML all lead to a syndication feed. Clicking on them will open that feed in your browser (or whatever application you've defined to handle the feed). Either your publication tool adds this to your site, or you can add it easilyjust create a hypertext link with the appropriate label.

To make your site easier to subscribe toafter all, not every reader is going to know what to do with this XML file that opensyou can also include buttons and links that specific aggregators provide, such as Bloglines, NewsGator, and so on. These should be marked clearly at the site, or instructions provided in the tool. Again, your publication tool may also provide this.

The best approach of all to publicize a feed is to use autodiscovery. Autodiscovery involves putting a simple line into the HEAD section of each web document, and pointing the reference to the location of your feed. You also provide some information about the type of feed so that aggregators know how to find it.

An autodiscovery link looks as follows, depending on your publication tool:

   <link rel="alternate" type="application/rdf+xml" title="Entries in RSS 1.0"           href="http://yourwebsiteloc.com/index.rdf" />

In this, the feed is RSS 1.0, located at http://yourwebsiteloc.com/index.rdf, and the type of file is application/rdf+xml. You can change the title to what you would prefer.

Your publication tool may provide much of this, like the following, in which case you'll want to use caution before changing the text:

   <link rel="alternate" type="application/rdf+xml" title="Entries in RSS 1.0"           href="<?php echo get_settings('siteurl'); ?>/index.rdf" />

And you can provide multiple feeds, such as different formats, or a feed specifically for your comments, such as the following:

   <link rel="alternate" type="application/rss+xml"           title="Recent comments in RSS 2.0"           href="http://yourwebsiteloc.com/commentsrss2.php" />

The application type for RSS 1.x is application/rdf+xml; the one for RSS 2.0 is application/rss+xml; the one for Atom is application/atom+xml.

When you add this to a page, and your readers access the page with a syndication feed-sensitive browser, such as Firefox, your readers will see an indicator that the site has an associated feed(s) and that they may subscribe. If your readers put the URL for your site into whatever aggregator they use, again it should find the link to the syndication feed, with no other effort on your part.

You, too, can find the syndication feed for sites you want to subscribe to using any of these same techniques, and whichever aggregator you prefer. We'll look at a sampling of aggregation tools in the next section.