code: function Request(config, operation, params) {
      var endpoint = new TableStore.Endpoint(config.endpoint);
      var region = config.region;
      this.config = config;
      if (config.maxRetries !== undefined) {
        TableStore.DefaultRetryPolicy.maxRetryTimes = config.maxRetries;
      }
      //如果在sdk外部包装了一层domain，就把它传到this.domain
      this.domain = domain && domain.active;
      this.operation = operation;
      this.params = params || {};
      this.httpRequest = new TableStore.HttpRequest(endpoint, region);
      this.startTime = TableStore.util.date.getDate();
  
      this.response = new TableStore.Response(this);
      this.restartCount = 0;
      this._asm = new AcceptorStateMachine(fsm.states, 'build');
  
      TableStore.SequentialExecutor.call(this);
      this.emit = this.emitEvent;
    }
docs: Creates a request for an operation on a given service with
  a set of input parameters.
  
  @param config [TableStore.Config] the config to perform the operation on
  @param operation [String] the operation to perform on the service
  @param params [Object] parameters to send to the operation.
  See the operation's documentation for the format of the
  parameters.