code: public void get(String key, UserDataHandler handler) {
  		if (cache.containsKey(key)) {
  			try {
  				handler.data(key, cache.get(key));
  			} catch (Exception e) {
  				e.printStackTrace();
  			}
  			return;
  		}
  
  		user.sendGlobal("JWWF-storageGet", "{\"key\":" + Json.escapeString(key) + "}");
  
  		if (waitingHandlers.containsKey(key)) {
  			waitingHandlers.get(key).push(handler);
  		} else {
  			LinkedList<UserDataHandler> ll = new LinkedList<UserDataHandler>();
  			ll.push(handler);
  			waitingHandlers.put(key, ll);
  		}
  	}
docs: Gets userData string. if data exists in cache the callback is fired
  immediately, if not async request is sent to user. If user don't have
  requested data, empty string will arrive
  
  @param key     Requested key
  @param handler Handler to be invoked when data arrives