Atom is an XML-based document format and HTTP-based protocol designed for the syndication of Web content such as weblogs and news headlines to Web sites as well as directly to user agents. It is based on experience gained in using the various versions of RSS. Critics have argued that it has merely created additional confusion.

Atom is a work-in-progress within the IETF [1]. Implementors are urged to wait until the spec is finished before deploying it, so that interoperability problems are minimized [2].

The last draft specification before the Atom work formally entered the IETF process is referred to as "Atom 0.3", and has support from a fairly wide variety of syndication tools both on the publishing and consuming side. In particular, it is generated by several Google-related services, namely Blogger and Gmail.

As well as a replacement for RSS (the "Atom Syndication Format"), the Atom Project is producing the "Atom Publishing Protocol", with a similar aim of improving on and replacing existing publishing mechanisms, such as the Blogger API and LiveJournal XML-RPC Client/Server Protocol. Atom was previously known as "Echo".

The latest Atom data format and publishing protocols are linked from the Working Group's home page.

Example

An example of an Atom Feed document:

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://purl.org/atom/ns#draft-ietf-atompub-format-07">
  <title type="text">dive into mark</title>
  <subtitle type="html">
    A <em>lot</em> of effort
    went into making this effortless
  </subtitle>
  <updated>2005-04-02T12:29:29Z</updated>
  <id>tag:example.org,2003:3</id>
  <link rel="alternate" type="text/html"
   hreflang="en" href="http://example.org/"/>
  <copyright>Copyright (c) 2003, Mark Pilgrim</copyright>
  <generator uri="http://www.example.com/" version="1.0">
    Example Toolkit
  </generator>
  <entry>
    <title>Atom draft-07 snapshot</title>
    <link rel="alternate" type="text/html"
     href="http://example.org/2005/04/02/atom"/>
    <link rel="enclosure" type="audio/mpeg" length="1337"
     href="http://example.org/audio/ph34r_my_podcast.mp3"/>
    <id>tag:example.org,2003:3.2397</id>
    <updated>2005-04-02T12:29:29Z</updated>
    <published>2003-12-13T08:29:29-04:00</published>
    <author>
      <name>Mark Pilgrim</name>
      <uri>http://example.org/</uri>
      <email>f8dy@example.com</email>
    </author>
    <contributor>
      <name>Sam Ruby</name>
      <uri>http://intertwingly.net/blog/</uri>
    </contributor>
    <contributor>
      <name>Joe Gregorio</name>
      <uri>http://bitworking.org/</uri>
    </contributor>
    <content type="xhtml" xml:lang="en"
     xml:base="http://diveintomark.org/">
      <div xmlns="http://www.w3.org/1999/xhtml">
        <p><i>[Update: The Atom draft-07 snapshot is out.]</i></p>
      </div>
    </content>
  </entry>
</feed>

See also

• Wikipedia:Syndication
• List of content syndication markup languages
• Comparison of content syndication markup languages
• FeedBurner, an Atom to RSS converter

External links

• IETF Atom Publishing Format and Protocol working group (atompub)
• Atom Wiki - The main place for work on Atom.
• AtomEnabled.org - An unofficial website following the Atom project
• The great syndication wars
• Why we need Echo
• Should Atom Use RDF?