code: Object _getDataService(T session, Class cls) throws DataServiceException {
  		String dataServiceClassName = cls.getName();
  		DataService dataServiceAnno = (DataService) cls.getAnnotation(DataService.class);
  		IDataServiceResolver resolver = getResolver(dataServiceAnno.resolver());
  		Scope scope = resolver.getScope(cls);
  		Object dataService = null;
  		Map<String, Object> sessionBeans = getSessionBeans(session);
  		logger.debug("{} : scope : {}", dataServiceClassName, scope);
  		if (scope.equals(Scope.SESSION)) {
  			dataService = sessionBeans.get(dataServiceClassName);
  			logger.debug("{} : scope : session is in session : {}", dataServiceClassName, (dataService != null));
  		}
  		if (dataService == null) {
  			dataService = resolver.resolveDataService(cls);
  			if (scope.equals(Scope.SESSION)) {
  				logger.debug("Store {} scope session in session", dataServiceClassName);
  				sessionBeans.put(dataServiceClassName, dataService);
  			}
  		}
  		return dataService;
  	}
docs: Get Dataservice, store dataservice in session if session scope.<br>
  
  @param session
  @param cls
  @return
  @throws DataServiceException