The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feed
Web feed
A web feed is a data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe to it.... s, while the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.
Web feeds allow software programs to check for updates published on a web site. To provide a web feed, a site owner may use specialized software (such as a content management system
Content management system
A content management system is a computer application used to create, edit, manage, search and publish various kinds of Content . CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures.... ) that publishes a list (or "feed") of recent articles or content in a standardized, machine-readable format.
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The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feed
Web feed
A web feed is a data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe to it.... s, while the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.
Web feeds allow software programs to check for updates published on a web site. To provide a web feed, a site owner may use specialized software (such as a content management system
Content management system
A content management system is a computer application used to create, edit, manage, search and publish various kinds of Content . CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures.... ) that publishes a list (or "feed") of recent articles or content in a standardized, machine-readable format. The feed can then be downloaded by web sites that syndicate content from the feed, or by feed reader programs that allow Internet users to subscribe to feeds and view their content.
A feed contains entries, which may be headlines, full-text articles, excerpts, summaries, and/or links to content on a web site, along with various metadata
Metadata
Metadata is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema.... .
The Atom format was developed as an alternative to RSS
RSS
RSS is a three-letter abbreviation that can stand for a wide variety of terms.... . Ben Trott, an advocate of the new format that became Atom, believed that RSS had limitations and flaws—such as lack of on-going innovation and its necessity to remain backward compatible— and that there were advantages to a fresh design.
Proponents of the new format formed the IETF Atom Publishing Format and Protocol Workgroup. The Atom syndication format was published as an IETF "proposed standard" in RFC 4287, and the Atom Publishing Protocol was published as .
Usage
Web feeds are used by the weblog community to share the latest entries' headlines or their full text, and even attached multimedia files. These providers allow other websites to incorporate the weblog's "syndicated" headline or headline-and-short-summary feeds under various usage agreements. Atom and other web syndication formats are now used for many purposes, including journalism, marketing, bug-reports, or any other activity involving periodic updates or publications. Atom also provides a standardized way to export an entire blog, or parts of it, for backup or for importing into other blogging systems.
A program known as a feed reader or aggregator can check webpages on behalf of a user and display any updated articles that it finds. It is common to find web feeds on major Web sites, as well as many smaller ones. Some websites let people choose between RSS or Atom formatted web feeds; others offer only RSS or only Atom. In particular, many blog
Blog
A blog is a type of website, usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video.... and wiki
Wiki
A wiki is a page or collection of Web pages designed to enable anyone who accesses it to contribute or modify content , using a simplified markup language.... sites offer their web feeds in the Atom format.
In computer networking, the term client-side refers to operations that are performed by the Client in a client-server relationship.Typically, a client is a computer application, such as a web browser, that runs on a user 's local computer or workstation and connects to a server as necessary.... readers and aggregators may be designed as standalone programs or as extensions to existing programs like web browser
Web browser
A Web browser is a application software which enables a user to display and interact with text, images, videos, music, games and other information typically located on a Web page at a website on the World Wide Web or a local area network.... s. Browsers are moving toward integrated feed reader functions. Such programs are available 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) web feeds into new feeds, e.g., taking all football related items from several sports feeds and providing a new football feed. There are several search engines which provide search functionality over content published via these web feeds.
On Web pages, web feeds (Atom or RSS) are typically linked with the word "Subscribe" or with the unofficial web feed logo (
).
Atom compared to RSS 2.0
When Atom emerged as a format intended to rival or replace RSS
RSS (file format)
RSS is a family of Web feed formats used to publish frequently updated works?such as blog entries, news headlines, audio, and video?in a standardized format.... , CNET
CNET
CNET Networks, Inc. was a mass media corporation based in San Francisco, California, United States. The company was co-founded in 1993 by Halsey Minor and Shelby Bonnie.... described the motivation of its creators as follows: "Winer's
Dave Winer
Dave Winer is an United States software developer and entrepreneur in Berkeley, California, California. A pioneer in the areas of RSS as "Really Simple Syndication", XML-RPC, OPML, outliners, and the MetaWeblog API, he is also the author of , one of the oldest Blog, established in 1997.... opponents are seeking a new format that would clarify RSS ambiguities, consolidate its multiple versions, expand its capabilities, and fall under the auspices of a traditional standards organization."
A brief description of some of the ways Atom 1.0 differs from RSS 2.0 has been given by Tim Bray
Tim Bray
Timothy William Bray is a Canadian software developer and entrepreneur. He co-founded Open Text Corporation and Antarctica Systems. Currently, Tim is the Director of Web Technologies at Sun Microsystems.... , who played a major role in the creation of Atom:
Content Model
RSS 2.0 may contain either plain text or escaped HTML as a payload, with no way to indicate which of the two is provided. Atom, on the other hand, provides a mechanism to explicitly and unambiguously label the type of content being provided by the entry, and allows for a broad variety of payload types including plain text, escaped HTML
HTML
HTML, an Acronym and initialism of HyperText Markup Language, is the predominant markup language for Web pages. It provides a means to describe the structure of text-based information in a document?by denoting certain text as links, headings, paragraphs, lists, and so on?and to supplement that text with interactive forms, embedded '... , XHTML
XHTML
The Extensible Hypertext Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax.... , XML, Base64
Base64
The term Base64 refers to a specific MIME#Content-Transfer-Encoding. It is also used as a generic term for any similar encoding scheme that encodes binary data by treating it numerically and translating it into a base 64 representation.... -encoded binary, and references to external content such as documents, video, audio streams, and so forth.
Date Formats
The RSS 2.0 specification relies on the use of RFC 822 formatted timestamps to communicate information about when items in the feed were created and last updated. The Atom working group chose instead to use timestamps formatted according to the rules specified by RFC 3339 (which is a subset of ISO 8601
ISO 8601
ISO 8601 is an international standard for calendar date and time representations issued by the International Organization for Standardization . Specifically, the standard is titled "Data elements and interchange formats ? Information interchange ? Representation of dates and times".... ).
RSS is a three-letter abbreviation that can stand for a wide variety of terms.... vocabulary has a mechanism to indicate a language for the feed, there is no means by which a language for individual items or text elements can be specified. Atom, on the other hand, uses the standardized xml:lang attribute to make it possible to specify a language context for every piece of human readable content in the feed.
On the Internet, the Internationalized Resource Identifier is a generalization of the Uniform Resource Identifier , which is in turn a generalization of the Uniform Resource Locator .... s, which allow links to resources and unique identifiers to contain characters outside the US ASCII
ASCII
American Standard Code for Information Interchange , is a coding standard that can be used for interchanging information, if the information is expressed mainly by the written form of English words.... character set.
RSS is a three-letter abbreviation that can stand for a wide variety of terms.... vocabulary are not generally reusable in other XML vocabularies. The Atom syntax was specifically designed to allow elements to be reused outside the context of an Atom feed document. For instance, it is not uncommon to find atom:link elements being used within RSS 2.0 feeds.
Barriers to adoption
Despite the emergence of Atom as an IETF Proposed Standard and the decision by major companies such as Google
Google
Google Inc. is an United States public company, earning revenue from AdWords related to its Google search, Gmail, Google Maps, Google Apps, Orkut, and YouTube services as well as selling advertising-free versions of the Google Search Appliance.... to embrace Atom, use of the older and more widely known RSS 1.0 and RSS 2.0 formats has continued.
RSS 2.0 support for enclosures led directly to the development of podcasting. While many podcasting applications, such as iTunes
ITunes
iTunes is a Proprietary software digital media media player application, used for playing and organizing digital music and video files. The program is also an interface to manage the contents on Apple's popular iPod digital media players as well as the iPhone.... , support the use of Atom 1.0, RSS 2.0 remains the preferred format.
Many sites choose to publish their feeds in only a single format. For example CNN
CNN
Cable News Network, almost always referred to by its initialism CNN, is a major US Cable News Network founded in 1980 by Ted Turner. Upon its launch, CNN was the first station to provide 24-hour television news coverage, and the first all-news television network in the United States.... , the New York Times, and the BBC offer their web feeds only in RSS 2.0 format.
News articles about web syndication feeds have increasingly used the term "RSS" to refer generically to any of the several variants of the RSS format such as RSS 2.0 and RSS 1.0 as well as the Atom format.
Each of the various web syndication feed formats has attracted large groups of supporters who remain satisfied by the specification and capabilities of their respective formats.
Sites that publish Atom will often publish RSS as well.
Development History
Background
Before the creation of Atom the primary method of web content syndication was the RSS
RSS (file format)
RSS is a family of Web feed formats used to publish frequently updated works?such as blog entries, news headlines, audio, and video?in a standardized format.... family of formats.
Members of the community who felt there were significant deficiencies with this family of formats were unable to make changes directly to RSS 2.0 because the official specification document stated that it was purposely frozen to ensure its stability.
Sam Ruby is a prominent software developer who has made significant contributions to many of the Apache Software Foundation's open source software projects, and to the standardization of web feeds via his involvement with the Atom web feed standard and the feedvalidator.org web service.... set up a wiki
Wiki
A wiki is a page or collection of Web pages designed to enable anyone who accesses it to contribute or modify content , using a simplified markup language.... to discuss what makes "a well-formed log entry". This initial posting acted as a rallying point. People quickly started using the wiki to discuss a new syndication format to address the shortcomings of RSS
RSS (file format)
RSS is a family of Web feed formats used to publish frequently updated works?such as blog entries, news headlines, audio, and video?in a standardized format.... . It also became clear that the new format could form the basis of a more robust replacement for blog editing protocols such as the Blogger API and LiveJournal
LiveJournal
LiveJournal is a virtual community where Internet users can keep a blog, journal or diary. LiveJournal is also the name of the free software and open source software Server software that was designed to run the LiveJournal virtual community.... XML-RPC Client/Server Protocol as well.
The project aimed to develop a web syndication format that was:
"100% vendor neutral,"
"implemented by everybody,"
"freely extensible by anybody, and"
"cleanly and thoroughly specified."
In short order, a project road map was built. The effort quickly attracted more than 150 supporters, including David Sifry of Technorati
Technorati
Technorati is an Internet search engine for searching blogs, competing with Google and Yahoo. As of June 2008, Technorati Web indexinges 112.8 million blogs and over 250 million pieces of tagged social media.... , Mena Trott of Six Apart
Six Apart
Six Apart Ltd., sometimes abbreviated 6A, is a software company headquartered in San Francisco, California, with an international presence in Paris and Tokyo.... , Brad Fitzpatrick
Brad Fitzpatrick
File:Brad Fitzpatrick by Anton Nossik.JPGBradley Joseph "Brad" Fitzpatrick , often seen on the Internet under the nickname bradfitz, is an United States programmer.... of LiveJournal
LiveJournal
LiveJournal is a virtual community where Internet users can keep a blog, journal or diary. LiveJournal is also the name of the free software and open source software Server software that was designed to run the LiveJournal virtual community.... , Jason Shellen of Blogger, Jeremy Zawodny
Jeremy Zawodny
Jeremy Zawodny is an incoming employee of Craigslist, having left Yahoo!'s platform engineering group. He has been described as "Yahoo!'s MySQL guru".... of Yahoo
Yahoo!
Yahoo! Inc. is an United States public company corporation with headquarters in Sunnyvale, California, , and provides Internet services worldwide.... , Timothy Appnel of the O'Reilly Network
O'Reilly Media
O'Reilly Media is an American Mass media company established by Tim O'Reilly that publishes books and web sites and produces conferences on computer technology topics.... , Glenn Otis Brown of Creative Commons
Creative Commons
Creative Commons is a non-profit organization devoted to expanding the range of creativity works available for others to build upon legally and to share.... and Lawrence Lessig
Lawrence Lessig
Lawrence Lessig is an United States Academia and political activist. He is a professor of law at Stanford Law School and founder of its Stanford Center for Internet and Society, and will soon re-join the faculty at Harvard Law School.... . Other notables supporting Atom include Mark Pilgrim
Mark Pilgrim
Mark Pilgrim is the author of Dive into Python, a guide to the Python and popular blogger. He is an advocate of Free Software and Dive into Python is published under the GNU Free Documentation License.... , Tim Bray
Tim Bray
Timothy William Bray is a Canadian software developer and entrepreneur. He co-founded Open Text Corporation and Antarctica Systems. Currently, Tim is the Director of Web Technologies at Sun Microsystems.... , Aaron Swartz
Aaron Swartz
Aaron Swartz is a writer, web developer, and entrepreneur. At age 14, he was a co-author of the RSS 1.0 specification. Since then he has become a member of the World Wide Web Consortium?s Resource Description Framework Core Working Group, co-designed the formatting language Markdown with John Gruber, and has been involved in many other proj... , Joi Ito
Joi Ito
, more commonly known as Joi Ito, is a Japanese activist, entrepreneur, and venture capitalist.Ito has received recognition for his role as an entrepreneur focused on Internet and technology companies and has founded, among other companies, PSINet Japan, Digital Garage and Infoseek Japan.... , and Jack Park. Also, Dave Winer
Dave Winer
Dave Winer is an United States software developer and entrepreneur in Berkeley, California, California. A pioneer in the areas of RSS as "Really Simple Syndication", XML-RPC, OPML, outliners, and the MetaWeblog API, he is also the author of , one of the oldest Blog, established in 1997.... , the key figure behind RSS 2.0
RSS (file format)
RSS is a family of Web feed formats used to publish frequently updated works?such as blog entries, news headlines, audio, and video?in a standardized format.... , gave tentative support to the new endeavor.
After this point, discussion became chaotic, due to the lack of a decision-making process. The project also lacked a name, tentatively using "Pie," "Echo," "Necho," and "PEAW" before settling on Atom. After releasing a project snapshot known as Atom 0.2 in early July 2003, discussion was shifted off the wiki.
Atom 0.3 and Adoption by Google
The discussion then moved to a newly set up mailing list. The next and final snapshot during this phase was Atom 0.3, released in December 2003. This version gained widespread adoption in syndication tools, and in particular it was added to several Google
Google
Google Inc. is an United States public company, earning revenue from AdWords related to its Google search, Gmail, Google Maps, Google Apps, Orkut, and YouTube services as well as selling advertising-free versions of the Google Search Appliance.... -related services, such as Blogger, Google News
Google News
Google News is an automated news aggregator provided by Google Inc. The initial idea, StoryRank?related to Google's PageRank formula?was developed by Krishna Bharat in 2001, the Principal Research Scientist of Google.... , and Gmail
Gmail
Gmail is a free Post Office Protocol and Internet Message Access Protocol webmail service provided by Google. In the United Kingdom and Germany it is officially called Google Mail.... . Google's Data APIs (Beta) GData
GData
GData provides a simple standard protocol for reading and writing data on the Internet, designed by Google. GData combines common XML-based syndication formats with a feed-publishing system based on the Atom Publishing Protocol, plus some extensions for handling queries.... are based on Atom 1.0 and RSS 2.0.
Atom 1.0 and IETF Standardization
In 2004, discussions began about moving the project to a standards body such as the World Wide Web Consortium
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web . It is arranged as a consortium where member organizations maintain full-time staff for the purpose of working together in the development of standards for the World Wide Web.... or the Internet Engineering Task Force
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the World Wide Web Consortium and International Organization for Standardization/International Electrotechnical Commission standard bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite.... (IETF). The group eventually chose the IETF and the Atompub working group was formally set up in June 2004, finally giving the project a charter and process. The Atompub working group is co-chaired by Tim Bray
Tim Bray
Timothy William Bray is a Canadian software developer and entrepreneur. He co-founded Open Text Corporation and Antarctica Systems. Currently, Tim is the Director of Web Technologies at Sun Microsystems.... (the co-editor of the XML specification) and Paul Hoffman. Initial development was focused on the syndication format.
The Atom Syndication Format was issued as a Proposed Standard in IETF RFC 4287 in December 2005. The co-editors were Mark Nottingham
Mark Nottingham
Mark Nottingham is an influential web infrastructure developer who is one of the authors of the Atom_ and WS-I Basic Profile specifications, the author of Request_for_Comments 4229: HTTP Header Registrations, and the chairman of the IETF HTTPBIS Working Group and W3C Web Services Addressing Working Group.... and Robert Sayre. This document is known as atompub-format in IETF's terminology. The Atom Publishing Protocol was issued as a Proposed Standard in IETF RFC 5023 in October 2007. Two other drafts have not been standardized.
Example of an Atom 1.0 Feed
An example of a document in the Atom Syndication Format:
Example FeedA subtitle.2003-12-13T18:30:02ZJohn Doejohndoe@example.comurn:uuid:60a76c80-d399-11d9-b91C-0003939e0af6
Atom-Powered Robots Run Amokurn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a2003-12-13T18:30:02ZSome text.
hAtom is a draft Microformat for marking up HTML content on World Wide Web that contain blog entries or similar chronological content. hAtom is also used by Internet Explorer 8 for using WebSlices within a page.... - microformat for marking up (X)HTML so that Atom feeds can be derived from it.
Sam Ruby is a prominent software developer who has made significant contributions to many of the Apache Software Foundation's open source software projects, and to the standardization of web feeds via his involvement with the Atom web feed standard and the feedvalidator.org web service....
Timothy William Bray is a Canadian software developer and entrepreneur. He co-founded Open Text Corporation and Antarctica Systems. Currently, Tim is the Director of Web Technologies at Sun Microsystems....
Dave Winer is an United States software developer and entrepreneur in Berkeley, California, California. A pioneer in the areas of RSS as "Really Simple Syndication", XML-RPC, OPML, outliners, and the MetaWeblog API, he is also the author of , one of the oldest Blog, established in 1997....
XML Shareable Playlist Format , pronounced spiff, is an XML-based playlist format for digital media, sponsored by the Xiph.Org Foundation. Lucas Gonze of Yahoo.com/Webjay.org originated the format in 2004....
Web syndication is a form of Broadcast syndication in which website material is made available to multiple other sites. Most commonly, web syndication refers to making web feeds available from a site in order to provide other people with a summary of the website's recently added content ....
A family tree of List of content syndication markup languagess, showing the closest predecessor and date of first major publication of each. Meta Content Framework...
Channel Definition Format is an XML standard used in conjunction with Microsoft Active Channel and Smart Offline Favorites technologies. Its use is to define a website's content and structure.... - an early feed format developed before Atom and RSS.
Content Management Interoperability Services is a standards proposal consisting of a set of Web services for sharing information among disparate content repositories that seeks to ensure interoperability for people and applications using multiple content repositories.... - Provides an extension to APP for Content Management
External links
Atom standard
RFC 4287 – "The Atom Syndication Format"
RFC 5023 - "The Atom Publishing Protocol"
- Xml.com column by Mark Pilgrim
- IBM Developer Works article by James Snell
- Overview of Atom-related IETF standards and drafts
Atom advocacy / evangelism
- An unofficial website following the Atom project
- A fusion of atom-related news
- Overview
Atom history & motivation
- the weblog post that started it all
- Motivation and goals of the Atom project
Atom working group links
- The main place for work on Atom.
- WG discussion of the publishing protocol
- WG discussion of the syndication format
Atom Extension Standards
- Official registry of atom:link element "rel" attribute values
HTML, an Acronym and initialism of HyperText Markup Language, is the predominant markup language for Web pages. It provides a means to describe the structure of text-based information in a document?by denoting certain text as links, headings, paragraphs, lists, and so on?and to supplement that text with interactive forms, embedded '... such that an Atom feed can be derived from it.
