Think about all of the information that you access on the Web on a day-to-day basis; news headlines, search results, “What’s New”, job vacancies, and so forth. A large amount of this content can be thought of as a list; although it probably isn’t in HTML
<li> elements, the information is list-oriented.
Most people need to track a number of these lists, but it becomes difficult once there are more than a handful of sources. This is because they have to go to each page, load it, remember how it’s formatted, and find where they last left off in the list.
RSS is an XML-based format that allows the syndication of lists of hyperlinks, along with other information, or metadata, that helps viewers decide whether they want to follow the link.
This allows peoples’ computers to fetch and understand the information, so that all of the lists they’re interested in can be tracked and personalized for them. It is a format that’s intended for use by computers on behalf of people, rather than being directly presented to them (like HTML).
To enable this, a Web site will make a feed, or channel, available, just like any other file or resource on the server. Once a feed is available, computers can regularly fetch the file to get the most recent items on the list. Most often, people will do this with an aggregator, a program that manages a number of lists and presents them in a single interface.
Feeds can also be used for other kinds of list-oriented information, such as syndicating the content itself (often weblogs) along with the links. However, this tutorial focuses on the use of RSS for syndication of links.
What’s in a feed?
A feed contains a list of items or entries, each of which is identified by a link. Each item can have any amount of other metadata associated with it as well.
The most basic metadata for an entry includes a title for the link and a description of it; when syndicating news headlines, these fields might be used for the story title and the first paragraph or a summary, for example. For example, a simple entry might look like:
<title>Earth Invaded</title> <link>http://news.example.com/2004/12/17/invasion</link> <description>The earth was attacked by an invasion fleet from halfway across the galaxy; luckily, a fatal miscalculation of scale resulted in the entire armada being eaten by a small dog. </description>
Additionally, the feed itself can have metadata associated with it, so that it can be given a title (e.g., “Bob’s news headlines”), description, and other fields like publisher and copyright terms.
For an idea of what full feeds look like, see ‘RSS Versions and Modules’.
How do people use feeds?
Aggregators are the most common use of feeds, and there are several types. Web aggregators (sometimes called portals) make this view available in a Web page; my Yahoo is a well-known example of this. Aggregators have also been integrated into e-mail clients, users’ desktops, or standalone, dedicated software.
Aggregators can offer a variety of special features, including combining several related feeds into a single view, hiding entries that the viewer has already seen, and categorizing feeds and entries.
Other uses of feeds include site tracking by search engines and other software; because the feed is machine-readable, the search software doesn’t have to figure out which parts of the site are important and which parts are just the navigation and presentation. You may also choose to allow people to republish your feeds on their Web sites, giving them the ability to represent your content as they require.
Why should I make a feed available?
Your viewers will thank you, and there will be more of them, because it allows them to see your site without going out of their way to visit.
While this seems bad at first glance, it actually improves your site’s visibility; by making it easier for your users to keep up with your site — allowing them to see it the way they want to — it’s more likely that they’ll know when something that interests them is available on your site.
For example, imagine that your company announces a new product or feature every month or two. Without a feed, your viewers have to remember to come to your site and see if they find anything new — if they have time. If you provide a feed for them, they can point their aggregator or other software at it, and it will give them a link and a description of developments at your site almost as soon as they happen.
News is similar; because there are so many sources of news on the Web, most of your viewers won’t come to your site every day. By providing a feed, you are in front of them constantly, improving the chances that they’ll click through to an article that catches their eye.
But isn’t that giving away my content?
No! You still retain copyright on your content (if you wish to).
You also control what information is syndicated in the feed, whether it’s a full article or just a teaser. Your content can still be protected by your current access control mechanisms; only the links and metadata are distributed. You can also protect the RSS feed itself with SSL encryption and HTTP username/password authentication too, if you’d like.
In many ways, syndication is similar to the subscription newsletters that many sites offer to keep viewers up-to-date. The big difference is that they don’t have to supply an e-mail address, lowering the barrier of privacy concerns, while still giving you a direct channel to your viewers. Also, they get to see the content in the manner that’s most convenient to them, which means that you get more eyes looking at your content.