RSS (file format)
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RSS is a family of XML file formats for web syndication used by news websites and weblogs. They are used to provide items containing short descriptions of web content together with a link to the full version of the content. This information is delivered as an XML file called RSS feed, webfeed, RSS stream, or RSS channel.
The acronym stands for one of the following standards:
- Rich Site Summary (RSS 0.91)
- RDF Site Summary (RSS 0.9 and 1.0)
- Really Simple Syndication (RSS 2.0)
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Usage
RSS is widely used by the weblog community to share the latest entries' headlines or their full text, and even attached multimedia files. (See podcasting, broadcatching and MP3 blogs.)
The first online news site to use RSS feeds was Variety.com in June of 2002. In 2004 and 2005, after several years of use by early adopters, use of RSS spread to many major news organizations, including Reuters and the Associated Press. Under various usage agreements, providers allow other websites to incorporate their "syndicated" headline or headline-and-short-summary feeds.
A program known as a feed reader or aggregator can check RSS-enabled webpages on behalf of a user and display any updated articles that it finds. It is now common to find RSS feeds on major web sites, as well as many smaller ones.
Client-side readers and aggregators are typically constructed as standalone programs or extensions to existing programs like web browsers. See List of news aggregators for a list of clients for various operating systems.
Web-based feed readers and news aggregators require no software installation and make the user's "feeds" available on any computer with Web access. Some aggregators syndicate (combine) RSS feeds into new feeds, e.g. take all football related items from several sports feeds and provide a new football feed. There are also search engines for RSS feeds like Feedster, Technorati, Pluck or Plazoo.
RSS feeds are typically linked to with an orange rectangle with the letters XML (Missing image
Small_Orange_XML_Button_for_RSS_Page.gif
XML iconic button
) or RSS (Missing image
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RSS iconic button
).
History
RDF Site Summary (RSS) was originally designed by Dan Libby of Netscape in 1999 for use on the My Netscape portal. But RDF tools were in short supply, which caused it to be stripped of much of its semantic feature set. While the format was technically valid RDF, it dropped many of the features (such as namespaces) necessary for actual RDF use [1] (http://groups.yahoo.com/group/rss-dev/message/239).
In the meantime, Dave Winer of UserLand Software had already designed his own XML syndication format for use on his Scripting News weblog, which he had been using since 1997 [2] (http://davenet.scripting.com/1997/12/15/scriptingNewsInXML).
Winer began working with Netscape, and many of the ScriptingNews syndication format's features were incorporated into the next revision of RSS. The new RSS 0.91 was renamed Rich Site Summary and dropped the pretense of using RDF. This resulted in a simpler XML format that was incompatible with the earlier version.
Some time after this, Netscape's interest in RSS disappeared, and UserLand took over as de facto maintainers. UserLand released its own version of RSS 0.91 with several minor incompatible changes.
In 2000 RSS was split into two development paths[3] (http://www.xmlhack.com/read.php?item=621), one that favored modularization, and one that believed that the complexity of namespaces should be avoided.
In August of 2000, a group of developers organized in the rss-dev (http://groups.yahoo.com/group/rss-dev/) mailing list published a proposed specification for RSS 1.0 (http://purl.org/rss/1.0/) [4] (http://groups.yahoo.com/group/syndication/message/372). This format reintroduced the originally intended RDF and was designed to allow for extension through modules (http://purl.org/rss/1.0/modules/). While it is often stated that RSS 1.0 is derived from and compatible with RSS 0.90, the two formats' use of different namespaces has been cited as a problematic source of incompatibility [5] (http://diveintomark.org/archives/2004/02/04/incompatible-rss).
The new, more complicated format was not well-received by many. Especially vocal were those who saw the name "RSS 1.0" as an attempt at hijacking their format [6] (http://groups.yahoo.com/group/syndication/message/410). An acrimonious debate about whether RSS 1.0 should be renamed played out on the rss-dev list and public weblogs, with both sides claiming that they had the right to the name.
Later in 2000, only ninteen days after the final publication of the RSS 1.0 specification, Winer published RSS 0.92 (http://backend.userland.com/rss092), a minor and (mostly) compatible improvement on RSS 0.91. Winer promoted the format to organizations including The New York Times.
In what was seen as an attack on the RSS 1.0 name, Winer published RSS 2.0 in 2002, emphasizing "Really Simple Syndication" as the meaning of the three-letter abbreviation. RSS 2.0 remained largely compatible with RSS 0.92, and added the ability to extend the format by placing extension elements in their own namespaces.
The latest version of the 2.x line is RSS 2.0.1. Winer and Userland Software assigned ownership of the new specification to Harvard's Berkman Center for the Internet & Society in 2003 and named an advisory board (http://blogs.law.harvard.edu/tech/advisoryBoard), from which Winer subsequently resigned.
Incompatibilities
RSS refers to multiple syndication formats (with multiple versions), which are all incompatible to some degree. Some disagree, pointing out that most developers have been able to support all the versions found in the field with only a moderate amount of complaining.
Additional incompatibilities arose when publishers began putting HTML content in an item's description, since most RSS specifications are unclear as to how embedded markup should be encoded. Other feed authors mixed features of the different standards, or added new features supported only by certain feed readers or aggregators, thus producing RSS feeds that do not meet any of the standards and sometimes are not even well-formed XML.
Partly because of these confusions and incompatibilities, the IETF developed a third similar (but differently-named) XML syndication format called Atom. (Some have argued that the creation of yet another format only confuses things further.)
See also
Reference
- RSS History (http://goatee.net/2003/rss-history.html)
- RSS 1.0 Specifications (http://web.resource.org/rss/1.0/)
- RSS 2.0 Specifications (http://blogs.law.harvard.edu/tech/rss)
- History of the RSS Fork (http://diveintomark.org/archives/2002/09/06/history_of_the_rss_fork)
- Dan Libby, "RSS: Introducing Myself" (http://groups.yahoo.com/group/rss-dev/message/239)
- The Myth of RSS Compatibility (http://diveintomark.org/archives/2004/02/04/incompatible-rss)
- RSS: beyond news sites and weblogs (http://freesoftwaremagazine.com/free_issues/issue_05/rss/)
- RSS Quick Summary (http://www.intertwingly.net/slides/2003/rssQuickSummary.html)Template:Interwikiconflict
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