In an attempt to present a detailed canonical answer, I will explain some of the basics (most of which I am sure you already know, and some of which I received reasonably about this).
XFN is a simple microformat for representing relationships. This allows you to require multiple sites as your own, as well as identify the sites of your friends, family, contacts and colleagues, etc. Many popular social networking sites support XFN in one form or another (twitter, flickr, facebook, Google profiles, etc.). It is commonly used in blogrolls.
I assume that the Google Social Graph API uses data collected by the Google Googlebot. For the Social Graph API, data obtained from the Googlebot function as an XFN spider. The XFN spider will navigate links, creating a social network of links by links.
Some of the Social Graph API commands ( search , otherme ) run queries on data collected by the Googlebot (so this is not a real-time query). If your site appears in Google search results, Googlebot has visited your site and everything will be fine, there should be a good chance that the Social Graph API can return results on your site. Using the sample sites kevinmarks.com, bradfitz.com, and another tantek.com example (all sites containing XFN markup), I was able to get API requests to return data.
The Social Graph API geturl team executes an online version of Python code hosted by google-sgnodemapper . This is used to create canonical form URLs for cases where slight differences in the " me " URLs from the same site are actually mapped to the same individual person (one node on the social graph).
The Social Graph API testparse team runs live analysis in real time on the original page (instead of using Googlebot / XFN data). I tried the Greasemonkey script and couldn't get it to work. I also tried:
<form method="post" action="https://socialgraph.googleapis.com/testparse"> <input type="hidden" name="url" value="http://kevinmarks.com/" /> <textarea name="body"> .....page source here...... </textarea> <input type="hidden" name="contentType" value="text/html" /> <input type="submit" /> </form>
For this view, I received the message " Service is unavailable. Please try again later. Error 503. " However, since this is a lab product, it is likely to be unavailable from time to time.
The Social Graph API website has the ability to make Googlebot crawl your site again using the Search Tool . However, to complete it, you need to register with Google Engage for agencies (which is related to AdWords).
To make sure your page has the appropriate XFN markup, you can use the bookmarklet, for example, the rel-lint XFN and rel-tag validator / lint tool, or possibly browser plug-ins like Chrome META inspector v1.8 .
In addition to supporting XFN, the Social Graph API also supports Friend of Friend ( FOAF ). FOAF is also a format that can also be used to represent relationships using RDF. FOAF is often expressed in XML, but other notations are possible (e.g. Notation3 ).
I saw a question about the Social Graph API group asking if the API worked. Thus, it would seem that other people are faced with some problems with its use.
The API requests themselves return formatted JSON data that you can collect and use as needed. The graphical context sample applications provide you with an online demonstration of the JSON responses that you would expect from passing various parameters to the search API command.
I hope this helps,