[buddypress-dev] Portable friends

[Chris Taylor - stillbreathing.co.uk]

Hi,

I've been thinking about the data portability issue recently and would
like some input on the 'friends' aspect. Some of the discussion so far
shows that some of the functionality required by a social network
'friends' feature can be handled well by the existing Wordpress
blogroll: which can contain a list of URIs which can be tagged with
XFN. One of the things BuddyPress could do (and also make a wider
Wordpress plugin) is handle the import/export and synchronisation of
these lists through OPML. That's relatively straightforward.

However there are other things that a friends application does that a
blogroll (currently) can't. Off the top of my head here's a few:

- Display the current status of each friend
- Display the latest post from each friend
- Show what topics your friends have been posting on
- Display recently-added photos from friends
- Compare favourites etc. with friends

I'm sure there are lots more (each of these may need a separate format
so they can be implemented separately). When the user and their
friends are in the same system, i.e. the same database, it's pretty
easy to make all these things happen - it's just a question of SQL
queries. But if these friends are going to be spread about not just
around the same site, but also blogs and other SNs then things start
to get hairy. The amount of data that could need to be transmitted
every time a user wants to check for their friends updates could be
prohibitive for site admins wanting this feature.

So my thoughts are that a users friends list *shouldn't* go to their
friends to see if data has changed. Instead when someone, for example,
updates their status that new text should be sent to anyone in their
friends list. Here's an example.

Bob and Dave are friends. Dave updates his status text, and the change
gets posted (using RPC?) to all of Dave's friends, including Bob. The
next time Bob logs in he sees Dave's latest status.

This minimises the amount of remote polling because friends' sites are
only called when there is has been an update made - not to check if
there *has* been an update made. It can also be made secure, because a
user could set their status updates to "everyone", but their photo
gallery updates only to "family".

Lastly it puts the status of the friendship under the data senders
control. Another example:

Jack has said he is Jill's friend. But Jill isn't Jack's friend, ever
since that part at Bob's house where he got a bit frisky by the punch
bowl. Jack might want to know when Jill updates her status message so
he can harass her, but he isn't going to get those notifications
automatically because he isn't in Jill's friends list. And because
Jack isn't in Jill's friends list she can say whether she wants to see
notifications from him or not, by leaving the "View updates from
people who say they are your friend (but you haven't said you are
theirs)?" box unchecked.

Any thoughts?

Chris