The feed URI scheme was a suggested uniform resource identifier (URI) scheme designed to facilitate subscription to web feeds; specifically, it was intended that a news aggregator be launched whenever a hyperlink to a feed
URI was clicked in a web browser. The scheme was intended to flag a document in a syndication format such as Atom or RSS. The document would be typically served over HTTP.
In 2006 the feed
URI scheme was supported by several popular desktop aggregators, including NetNewsWire, FeedDemon, Safari, and Flock. As of 2011 [update] no effort seems to be underway to officially register the scheme at IANA. [1]
Critics hold that the purpose of the feed
URI scheme is better served by MIME types, [2] 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.
The feed
URI scheme was suggested in 2003 [3] in draft-obasanjo-feed-URI-scheme-01 and 02. These expired drafts were not submitted as Internet drafts; the author later contributed to the work on the atom standard.
The syntax for a feed
URI may be expressed in Backus–Naur form as follows:
<feed_uri>::="feed:"<absolute_uri>|"feed://"<authority><path-abempty>
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://
.
The <authority> and <path-abempty> constructs in the syntax are specified in RFC 3986 also known as STD 66. Here <authority> is in essence the userinfo@host:port part of the original http
URI, and <path-abempty> is the following absolute path introduced by a slash "/"; it can be empty or absent. Therefore, the following are two examples of valid feed
URIs:
feed:https://example.com/entries.atomfeed://example.com/entries.atom
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In computer hypertext, a URI fragment is a string of characters that refers to a resource that is subordinate to another, primary resource. The primary resource is identified by a Uniform Resource Identifier (URI), and the fragment identifier points to the subordinate resource.
Percent-encoding, also known as URL encoding, is a method to encode arbitrary data in a Uniform Resource Identifier (URI) using only the limited US-ASCII characters legal within a URI. Although it is known as URL encoding, it is also used more generally within the main Uniform Resource Identifier (URI) set, which includes both Uniform Resource Locator (URL) and Uniform Resource Name (URN). As such, it is also used in the preparation of data of the application/x-www-form-urlencoded
media type, as is often used in the submission of HTML form data in HTTP requests.
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In HTTP, "Referer" is an optional HTTP header field that identifies the address of the web page, from which the resource has been requested. By checking the referrer, the server providing the new web page can see where the request originated.
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The geo URI scheme is a Uniform Resource Identifier (URI) scheme defined by the Internet Engineering Task Force's RFC 5870 as:
a Uniform Resource Identifier (URI) for geographic locations using the 'geo' scheme name. A 'geo' URI identifies a physical location in a two- or three-dimensional coordinate reference system in a compact, simple, human-readable, and protocol-independent way.
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. They are implemented in webservers so that requests to the servers for well-known services or information are available at URLs consistent well-known locations across servers.