title: Angular How to control a directive from a service?
body: <p>I'm trying to do a Service that control a directive.</p>
  
  <p>So the purpose is to use the Service in a Controller to ask the Directive to do something.</p>
  
  <p>eg. <code>SomeService.tellSomething('ok');</code> will trigger the directive with a param</p>
  
  <p>I know that we can use <code>$rootScope.$broadcast</code> to send/trigger event but I honestly don't know if it is a good practice...</p>
  
  <p>Any advices/techniques ?</p>