feed URI scheme

In computing, the feed: URI scheme (sometimes referred to, somewhat imprecisely, as the feed protocol; see Protocol (computing)) is a non-standard URI scheme designed to facilitate subscription to web feeds; specifically, it is intended that a news aggregrator be lauched whenever a hyperlink to a feed: URI is clicked in a web browser.

The feed: URI scheme is currently supported by several popular desktop aggregators, including NetNewsWire, FeedDemon, Safari, and Flock, although as of 2006 no effort seems to be underway to officially register the scheme with a standards body.

Critics hold that the purpose of the feed: URI scheme is better served by MIME types,^[1] or that it is not a user-friendly solution for the problem of feed subscription, since a user who has not installed the appropriate software will receive an unhelpful browser error message on clicking a link to a feed: URI.

Syntax

The syntax for a feed: URI may be expressed in Backus–Naur form as follows:

<feed_uri> ::= "feed:" <absolute_uri> | "feed://" <hier_part>

Specifically, a feed: URI may be formed from any absolute URI (such as an absolute URL) by prepending feed:, and as a special case, may be formed from any absolute http: URI by replacing the initial http:// with feed://. Therefore, the following are three examples of valid feed: URIs:

feed:example.com/rss.xml
feed://example.com/rss.xml
feed:https://example.com/rss.xml

There is also a proposed extension of the syntax that supports metadata and embedded instructions to the aggregator.^[2]

External links

• The feed URI scheme — pre-draft version of a specification from 2004
• The feed protocol format — including proposal for extensions