Ember-Data Network Adapter

Question

I need to create a websocket adapter to work with Ember data and came across this example in stackoverflow.

How to integrate websocket with emberjs?

But with all this I read about Ember, using promises, I wonder if code like the one shown in the example will work with the latest versions of Ember and Ember-data. All methods in adapters (e.g. find, findAll, createRecord, etc.) Should they return promises?

Conceptually, I think I understand what promises are for, but I really don't know how to use it. Can anyone know please explain?