The atomic age

The content format for OpenSocial is always the Atom syndication format, a competitor to RSS for syndicating blogs and other similar information. I haven’t spent very much time with Atom yet — I appreciate that it’s more fully-specified than RSS 2.0, but I already know RSS and have run into no practical problems with it (through I’m aware of the potential ones) — so I’m probably not going to notice if or where the OpenSocial specs are violating the spirit or even letter of the Atom specs. I’ve occasionally seen complaints from Atom-heads about Atom-compliance in Google’s GData, and assume those apply to OpenSocial as well.

People

When you ask an OpenSocial provider for information about a member (using the URL pattern http://{DOMAIN}/feeds/people/{userId}), the spec says you get back something like this, assuming you’re authorized to make the request (lifted straight from the spec, and not namespace-compliant):

<entry xmlns='http://www.w3.org/2005/Atom'
  xmlns:georss='http://www.georss.org/georss'
  xmlns:gd='http://schemas.google.com/g/2005'>
  <id>http://sandbox.orkut.com:80/feeds/people/14358878523263729569</id>
  <updated>2007-10-28T14:01:29.948-07:00</updated>
  <title>Elizabeth Bennet</title>
  <link rel='thumbnail' type='image/*'
    href='http://img1.orkut.com/images/small/1193601584/115566312.jpg'/>
  <link rel='alternate' type='text/html'
    href='http://orkut.com/Profile.aspx?uid=17583631990196664929'/>
  <link rel='self' type='application/atom+xml'
    href='http://sandbox.orkut.com:80/feeds/people/14358878523263729569'/>
  <georss:where>
    <gml:Point xmlns:gml='http://www.opengis.net/gml'>
      <gml:pos>51.668674 -0.066235</gml:pos>
    </gml:Point>
  </georss:where>
  <gd:extendedProperty name='lang' value='en-US'/>
  <gd:postalAddress/>
</entry>

Aside from the fact that the tech writer is a Jane Austen fan, a couple of other points jump out:

1. In addition to the Atom namespace, they’re using the GeoRSS namespace to provide lat/lon information (so that you could place the person on a map, for example), the GML namespace (which the example forgets to declare), and the GData namespace for generally unimportant information like the postal address (who gives that out?).
2. The two most important pieces of information seem to be the thumbnail picture/buddy icon and the member’s HTML profile page, both of which are the targets of typed links.

Of course, in reality, the most important information about a member is the member’s friends list, but that information comes through a separate URL, http://{DOMAIN}/feeds/people/{userId}/friends.

Friends

This example is also lifted from the spec (and is still missing the declaration for the GML namespace):

<feed xmlns='http://www.w3.org/2005/Atom'
  xmlns:openSearch='http://a9.com/-/spec/opensearchrss/1.0/'
  xmlns:georss='http://www.georss.org/georss'
  xmlns:gd='http://schemas.google.com/g/2005'>
  <id>http://sandbox.orkut.com:80/feeds/people/14358878523263729569/friends</id>
  <updated>2007-10-28T21:01:03.690Z</updated>
  <title>Friends</title>
  <link rel='http://schemas.google.com/g/2005#feed' type='application/atom+xml'
    href='http://sandbox.orkut.com:80/feeds/people/14358878523263729569/friends'/>
  <link rel='self' type='application/atom+xml' href='http://sandbox.orkut.com:80/feeds/people/14358878523263729569/friends'/>
  <author><name>Elizabeth Bennet</name></author>
  <entry>
    <id>http://sandbox.orkut.com:80/feeds/people/02938391851054991972</id>
    <updated>2007-10-28T14:01:03.690-07:00</updated>
    <title>Jane Bennet</title>
    <link rel='thumbnail' type='image/*' href='http://img1.orkut.com/images/small/null'/>
    <link rel='alternate' type='text/html' href='http://sandbox.orkut.com:80/Profile.aspx?uid=574036770800045389'/>
    <link rel='self' type='application/atom+xml' href='http://sandbox.orkut.com:80/feeds/people/02938391851054991972'/>
    <georss:where>
    <gml:Point xmlns:gml='http://www.opengis.net/gml'>
    <gml:pos>51.668674 -0.066235</gml:pos></gml:Point></georss:where>
    <gd:extendedProperty name='lang' value='en-US'/>
    <gd:postalAddress/>
  </entry>
  <entry>
    <id>http://sandbox.orkut.com:80/feeds/people/12490088926525765025</id>
    <updated>2007-10-28T14:01:03.691-07:00</updated>
    <title>Charlotte Lucas</title>
    <link rel='thumbnail' type='image/*' href='http://img2.orkut.com/images/small/null'/>
    <link rel='alternate' type='text/html' href='http://sandbox.orkut.com:80/Profile.aspx?uid=5799256900854924919'/>
    <link rel='self' type='application/atom+xml' href='http://sandbox.orkut.com:80/feeds/people/12490088926525765025'/>
    <georss:where>
    <gml:Point xmlns:gml='http://www.opengis.net/gml'>
    <gml:pos>0.0 0.0</gml:pos></gml:Point></georss:where>
    <gd:extendedProperty name='lang' value='en-US'/>
    <gd:postalAddress/>
  </entry>
  <entry>
    <id>http://sandbox.orkut.com:80/feeds/people/15827776984733875930</id>
    <updated>2007-10-28T14:01:03.692-07:00</updated>
    <title>Fitzwilliam Darcy</title>
    <link rel='thumbnail' type='image/*' href='http://img3.orkut.com/images/small/1193603277/115555466.jpg'/>
    <link rel='alternate' type='text/html' href='http://sandbox.orkut.com:80/Profile.aspx?uid=14256507824223085777'/>
    <link rel='self' type='application/atom+xml' href='http://sandbox.orkut.com:80/feeds/people/15827776984733875930'/>
    <georss:where>
    <gml:Point xmlns:gml='http://www.opengis.net/gml'>
    <gml:pos>53.017016 -1.424363</gml:pos></gml:Point>
    </georss:where>
    <gd:extendedProperty name='lang' value='en-US'/>
    <gd:postalAddress/>
  </entry>
</feed>

Again, very straight-forward, if not namespace-compliant (due to the missing GML namespace declaration). There’s also a declaration of an OpenSearch namespace URI that’s never used, suggesting a feature that was removed in haste just before release. The friends list is simply a feed of person entries, just like the single entry returned for the member query, with a title, date, etc. at the top. Note that you always get the full friends list — there’s no support for filtering — so this might not be fun for someone who has 10,000+ friends.

What I don’t see, either in the example or the spec, is a way to provide typed relationships, like “spouse”, “colleague”, “classmate”, etc. I don’t know how important that is to application developers — simply getting the list of friends is probably the most important thing.