Google Webfinger

This is pretty old news, but I missed the original announcement and I think it’s pretty interesting.

Google have implemented an alpha of the WebFinger protocol. If you have a Google profile, click on “Edit your profile” and add ‘webfingeralpha’ as an interest. Congrats, your gmail address is now a WebFinger identifier and will resolve to an XRD file containing information about services you use (if you’ve included that information in your Google profile).

This is pretty fun to play around with. Given an email-like identifier, such as evalpaul@gmail.com, get the host-meta XRD file for the domain:

paul@knuth ~ $ curl -i http://gmail.com/.well-known/host-meta
HTTP/1.1 200 OK
Content-Type: application/xrd+xml
Transfer-Encoding: chunked
Date: Mon, 01 Feb 2010 12:36:47 GMT
Expires: Mon, 01 Feb 2010 12:36:47 GMT
Cache-Control: private, max-age=0
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN
Server: GFE/2.0
...
<?xml version='1.0' encoding='UTF-8'?>
<!-- NOTE: this host-meta end-point is a pre-alpha work in progress.   Don't rely on it. -->
<!-- Please follow the list at http://groups.google.com/group/webfinger -->
<XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0' 
	xmlns:hm='http://host-meta.net/xrd/1.0'>
<hm:Host xmlns='http://host-meta.net/xrd/1.0'>gmail.com<;/hm:Host>
<Link rel='lrdd' 
		template='http://www.google.com/s2/webfinger/?q={uri}'>
	<Title>Resource Descriptor<;/Title>
</Link>
</XRD>

Now that you have the URI template, get the XRD file for the specific user:

curl "http://www.google.com/s2/webfinger/?q=acct%3Aevalpaul%40gmail.com"

And the response:

<?xml version='1.0'?>
<XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>
	<Subject>acct:evalpaul@gmail.com<;/Subject>
	<Alias>http://www.google.com/profiles/evalpaul<;/Alias>
	<Link rel='http://portablecontacts.net/spec/1.0' href='http://www-opensocial.googleusercontent.com/api/people/'/>
	<Link rel='http://webfinger.net/rel/profile-page' href='http://www.google.com/profiles/evalpaul' type='text/html'/>
	<Link rel='http://microformats.org/profile/hcard' href='http://www.google.com/profiles/evalpaul' type='text/html'/>
	<Link rel='http://gmpg.org/xfn/11' href='http://www.google.com/profiles/evalpaul' type='text/html'/>
	<Link rel='http://specs.openid.net/auth/2.0/provider' href='http://www.google.com/profiles/evalpaul'/>
	<Link rel='describedby' href='http://www.google.com/profiles/evalpaul' type='text/html'/>
	<Link rel='describedby' href='http://s2.googleusercontent.com/webfinger/?q=evalpaul%40gmail.com&amp;fmt=foaf' type='application/rdf+xml'/>
</XRD>

EDIT: Google have since rolled out WebFinger support for everyone with a Google Profile. You no longer need to add ‘webfingeralpha’ to your interests.

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