In Ember everything developed around the URL. In an Ember application you define your routes in a DSL that looks like the following.
Ember.Router.map(function () {
this.resource('profile', { path: '/:profile_id' });
});
So when a user goes to profile/123 what happens that URL maps to ProfileRoute where the url is serialized and passed to the model hook so you can ask the data store to preform a GET on /api/profile/123.