[OpenID] Group Membership Protocol on LiveJournal

[Martin Atkins]

Hi Folks,

I just noticed that my experimental server implementation of the simple 
Group Membership Protocol[1] has gone live on LiveJournal.com, so every 
LiveJournal user's friends list and community's members list is now a 
queryable group.

Group Membership Protocol is a very simple means by which a group of 
URIs (which are probably OpenID identifiers, but don't necessarily need 
to be) can be enumerated and queried.

The group URL for each user is http://username.livejournal.com/friends 
and the endpoint currently lives at:
     http://www.livejournal.com/openid/groupmembership.bml

For example, I'll pick on Brad because he's one of the few LJ users I 
know that has some OpenID-ish users on his friends list:

http://www.livejournal.com/openid/groupmembership.bml?grpmember.group=http://brad.livejournal.com/friends
http://www.livejournal.com/openid/groupmembership.bml?grpmember.group=http://brad.livejournal.com/friends&grpmember.identifier=http://mart.degeneration.co.uk/
http://www.livejournal.com/openid/groupmembership.bml?grpmember.group=http://brad.livejournal.com/friends&grpmember.identifier=http://daveman692.livejournal.com/

I believe that this is currently the only mechanism on LiveJournal by 
which you can enumerate all of a user's friends including those who 
logged in with OpenID.


[1] http://openid.net/wiki/index.php/Group_Membership_Protocol