presence

=== Current client API ===

client.onClientLogin( callback ); 
// subscribes the client to 'client logins' - PRESENCE_JOIN is the constant I'm using
client.onClientLogout( callback );
// subscribes 'client logouts' - PRESENCE_REMOVE
client.getConnectedClients( callback );
// sends a PN|Q+ - essentially just a query on C.TOPIC.PRESENCE

=== Current server implementation === 
- uses both a DistributedStateRegistry (DSR) and a SubscriptionRegistry (SR). 
    - DSR keeps track of connected clients, something that is not really easy to do with a SR.
    - SR keeps track of subscriptions to the actions/events PRESENCE_REMOVE and PRESENCE_LOGIN

So when a clientA logs in, clients who are subscribed to PRESENCE_JOIN will be notified.

=== tests ===
Have set up some unit tests in both repos and some single node e2e ones in the client repo - seems to work quite well.