1 to send http request, and the template to handle the success event and error event:
the advantage of this method is invoker need support a callback function, which is highly coupled.
2 still in service, but this is a new method to call http without coupling. (by $q defer)
this is the service likes:
this is the service caller likes:
after angularjs 1.2, this caller should be written like this: (by $promise)
3 by using $resource to call restful backend: