The world of Syndication: Atom 1.0 vs. RSS 2.0?

Posted: Oct 06, 2008  5 comments  

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Newspaper_Feed_64x64 Syndication has become and inseparable part of the internet. There are two major syndication formats that exist today – RSS 2.0 (Really Simple Syndication) and Atom 1.0 (Atom Syndication Format). While they achieve the same end result, there are differences. This post attempts to enable you to decide which is more suited to your publishing.

RSS 2.0 is a frozen specification copyrighted by Harvard and Atom 1.0 is a specified in RFC4287. Atom came about as a result of pursuit to fix shortcoming of RSS since RSS was a frozen format. The table below lists the differences in the two specifications/standards:

  Atom 1.0 RSS 2.0 Who wins?
Content Model Allows text, escaped HTML, well-formed XHTML, XML, base-64 encoded binary or pointer to web content outside the feed. Text or Escaped HTML This is a major advantage for Atom, writing escaped HTML affects the readability of RSS feeds
Partial Content Has separate <summary> or <content> tags. Has a <description> field. This could contain complete content or just synopsis but has no way of identifying what it contains. This is another win for Atom, helps you have a synopsis and complete view inside a feed reader
Auto Discovery Uses the MIME Type  application/atom+xml which is registered with IANA. In addition the feed has a self link to enable auto subscription in readers The MIME Type application/rss+xml is often used but not recognized by IANA Having a registered MIME Type and auto subscription really helps discovery. Another Atom win.
Format Flexibility Atom syndication format allows entries linking to the feed or standalone entries RSS only recognizes a <rss> document. This is also an Atom win, having standalone entries enables scenarios like linking to entries only.
Extensibility Atom defines a well-defined structure to extend the default namespace and has specific guidelines on readers should interpret these. RSS has to fixed namespace, however you could include external XML namespaces. Atom has a slight advantage here as external namespaces extensions in RSS are not easily discoverable. In Atom’s case these extensions have a corresponding namespace tag
Languages Atom uses xml:lang for language specificity RSS has a separate <language> tag for language specificity No one.
Encryption Atom allows the option to encrypt entries using XML Encryption or XML Digital Signature. In addition the feed could be encrypted entire feed using standard web encryption techniques RSS only allows encrypting using standard web encryption techniques. Atom has extra level of encryption possible.
Adoption Most sites that publish both RSS and Atom feeds. Most sites that publish both RSS and Atom feeds. RSS has an advantage of being the first mover, the term RSS has become synonymous with syndication.
Modularity All elements part of Atom’s namespace can be used outside Atom’s context due to way it was designed RSS elements cannot be used outside the context of RSS This has proved to be the one of the major factors of Atom’s popularity and its used in data interactions like those enabled by Google GData

As you might have realized that Atom has considerable benefits over RSS. More and more services online are using Atom as more than just a feed format. Google’s GData and Microsoft’s Project Astoria are great examples and testimonies of Atom 1.0’s strengths as a format. They extend its namespace and harness the capabilities of Atom Publishing Protocol to pass data between their services.

While, I was writing, I realized that I was still publishing an RSS 2.0 feed for my blog (default supported by Drupal). I switched it to Atom 1.0. Have you? My recommendation to you would be switch to Atom as your base feed. Having said that, RSS is still very popular and consumed by many, it is good to retain your RSS feed too. Atom preserves most aspects of RSS so a simple transform (e,g, using XSLT) should be able to help you create and RSS feed from the Atom one.

If you know more examples that demonstrate Atom / RSS’s strength please post your comments below. I would love to hear from you.

Additional Reading:

Comments

Thanks for the article.  It's clear for me now that I will use Atom.

Oct 06 2008 by Anonymous

Google Chrome has no RSS?

Jan 31 2009 by Anonymous

This article was very useful and made understanding the differences easy. Thank you.

One short note, while reading it I noticed that you wrote, "RSS 2.0 is a frozen specification copyrighted by Harvard" which I do not think is an accurate description.

The specification is licensed under Creative Commons 1.0 BY-SA by Berkman Center for Internet & Society at Harvard Law School. The full description of the license and attribution requirements can be found at: cyber.law.harvard.edu/.../rss.html

It has been 200 days since you wrote this article, so things may have changed since initial publication. I think it is worth updating the article to reflect this change since the current state of the RSS 2.0 specification is now much more open.

Apr 23 2009 by davidblair

I think use-cases are important to add as well... here's how I see it based on the understanding gained here, past experience with both formats and the specifications themselves:

ATOM

- Lists of Users (extended via FOAF)

- User Activities (i.e. shared links, status updates; extended via ActivityStrea.ms)

- Group Discussions (extended via SIOC)

- Full Content Feeds (i.e. entire news articles; possibly extended via NewsML, SportsML, DublinCore or others)

RSS

- Summary of general website updates (new articles, blog posts, comments, etc)

- Video Sitemaps (extended via Yahoo!'s MediaRSS)

- New files added to servers (i.e. torrents, portfolio work etc, extended via E-Commerce and/or OpenSearch module)

Mar 17 2011 by bcmoney

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