postMessage vs Promise

// faremos uns postMessage esperando o melhor.
angular.module("roundabout").factory("coreservice",function($http,$q){
  var serverpoint = window.frames["serverpoint"];
  var CoreService = {
    process:function(data){
      var deferred = $q.defer();
      data.ticket = "ticket-"+(new Date().getTime());
      // TODO adcionar um equema de timeout aqui
      // var subject = data.subject;
      // var payload = data.payload;
      if(!serverpoint)
        serverpoint=window.frames["serverpoint"];
      var cbk = function(event){
        if(event.data.ticket==data.ticket){
          deferred.resolve(event.data);
          window.removeEventListener(cbk);
        }
      };
      window.addEventListener("message",cbk)
      if(serverpoint.postMessage){
        serverpoint.postMessage(data,"*");
      }else{
        console.debug("serverpoint not ready");
        deferred.reject("serverpoint not ready");
      }
      return deferred.promise;
    }
  };
  window.addEventListener("message",function(evt){
    if(CoreService[evt.data.subject])
      CoreService[evt.data.subject](evt.data.payload);
  });
  return CoreService;
});