Atom is a Syndication Format similar to RSS. It is an XML-based document format that describes lists of related information known as "feeds". Feeds are composed of a number of items, known as "entries", each with an extensible set of attached metadata. For example, each entry has a title. (If you were looking for the Atom Processor see X86.)
The primary use case that Atom addresses is the syndication of Web content such as weblogs and news headlines to Web sites as well as directly to user agents. An Atom file will typically have a .atom extension.
This format was developed to overcome some limitations in the RSS format. These include:
- Provides a way to identify content as to form.
- Atom working group uses timestamps formatted according to the rules specified by RFC 3339 (which is a subset of ISO 8601).
- Provide language data on individual entries using the standardized xml:lang attribute (RFC 3066)
- Provides support for the use of Internationalized Resource Identifiers. This permits URLs to have non ascii characters.
- Atom has separate <summary> and <content> elements. The summary is encouraged for accessibility reasons if the content is non-textual (e.g. audio) or non-local (i.e. identified by pointer). Content, if supplied, is expected to be complete.
The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol (short AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.
Some sites, such as this wiki, have support for both Atom and RSS but some site choose one or the other.
A brief, single-entry Atom Feed Document. The information between entry and /entry can be repeated as needed to add to the feed.
<?xml version="1.0" encoding="utf-8"?> <feed xmlns="http://www.w3.org/2005/Atom"> <title>Example Feed</title> <link href="http://example.org/"/> <updated>2003-12-13T18:30:02Z</updated> <author> <name>John Doe</name> </author> <id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id> <entry> <title>Atom-Powered Robots Run Amok</title> <link href="http://example.org/2003/12/13/atom03"/> <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id> <updated>2003-12-13T18:30:02Z</updated> <summary>Some text.</summary> </entry> </feed>
An entry section will typically have a summary and or a content section. Content may be text (type TEXT or HTML or XHTML) or a URL.