RSS Auto Discovery

RSS is meant to be consumed by machines and software, not by humans. The accronym is meaningless and we should not expose it to users. The orange wave icon is similarly cryptic and we should rather show actionable buttons to our readers and users when we want them to subscribe to the content we publish.

When the users subscribe (or follow) to a pages, they do it in the context of said page. For example, on this very blog, you can subscribe using the button at the bottom of this post. This means that the application which handles the subscription is probably passed something like this page’s URL.

Auto-discovery

From the URL, we should also make it as easy as possible for the machines to find the corresponding RSS feed. This mechanism is called Auto-discovery and is performed using a rather simple mechanism: a simple <link> tag to add inside the <head> section of the HTML document.

The tag includes 4 important elements:

• rel should include alternate which tells the application that the linked document contains an alternate view of the current document/page. You can also use the feed value, even though, in our experience, this is much less frequent. Using both is probably a safe bet
• type indicates the MIME type of this alternate representation. RSS uses application/rss+xml while Atom uses application/atom+xml
• title is a human description of the document. It’s good to re-use the page’s title. Do not add RSS as it’s meaningless for people :)
• href is the most important attribute: it’s the URL (relative or absolute) of the feed.

Here’s, for example, the discovery for this blog’s main feed:

<link rel="alternate feed" type="application/atom+xml" title="Superfeedr Blog" href="/atom.xml">

You should probably have a single feed per HTTP resource. However, if you serve multiple resources, you should have one feed (alternate view of the content) per resource.

Link Back

Finally, inside your feeds, it’s important to link back to the HTML resource. This lets feed readers point to the right site (or section).

The mechanism using Atom is identical to auto-discovery: it’s a <link> element with rel="alternate" and type=”text/html”. It's also safer to use an absolute URL here for the href` attribute.

<link href="http://blog.superfeedr.com/" rel="alternate" type="text/html"/>

For RSS, it’s a little less “defined”, but you can easily include the Atom namespace and follow the Atom way. Alternatively, you can use RSS’s <link> element like Dave Winer’s feed:

<link>http://scripting.com/</link>