code: func (cfgSrcHandler *Handler) DynamicConfigHandler(callback core.DynamicConfigCallback) error {
  	if cfgSrcHandler.initSuccess != true {
  		return errors.New("config center source initialization failed")
  	}
  
  	dynCfgHandler, err := newDynConfigHandlerSource(cfgSrcHandler, callback)
  	if err != nil {
  		openlogging.GetLogger().Error("failed to initialize dynamic config center Handler:" + err.Error())
  		return errors.New("failed to initialize dynamic config center Handler")
  	}
  	cfgSrcHandler.dynamicConfigHandler = dynCfgHandler
  
  	if cfgSrcHandler.RefreshMode == 0 {
  		// Pull All the configuration for the first time.
  		cfgSrcHandler.refreshConfigurations("")
  		//Start a web socket connection to recieve change events.
  		dynCfgHandler.startDynamicConfigHandler()
  	}
  
  	return nil
  }
docs: //DynamicConfigHandler dynamically handles a configuration