@chikoon Yes, we are watching for changes.

`updatedFeedsService` is a good start, you'll see that that service exposes `events`.
The other service to look for is `apiEventService`.

That last service makes sure that whenever there is a change in any `events` object on any service, there will be a `$broadcast` in a unified way:
`$rootScope.$broadcast('calcentral.api.' + apiName + '.' + eventName, data);`

As for the 2 arguments, that's a default in AngularJS, have a look at
http://docs.angularjs.org/api/ng/type/$rootScope.Scope#$on

> The event listener function format is: function(event, args...)