A couple of times, the article mentions using:

> services and object references to propagate object changes between scopes.

There are so many ways to wire things up in Angular -- references, watches, broadcast/emit -- that I'd love to see some examples from the author, who seems to really know what he's doing.

For example, say I have a `userService` that maintains a small `user` model with username, name and roles properties. What's the most performant and maintainable way of "binding" to changes to this object so when I call, e.g.: `userService.logout()` somewhere, some component I write can pickup the change and adjust it's state / UI accordingly?