code: function(err, res) {
  	      console.log(err);
  	      res.reply(mInstance.conf.CONST.ERR);
  	      return;
  	    }
docs: /*
  Called when an error occurs. Respond plain text conf.CONST.ERR to
  client by default.
  
  *err*, message of the error, will be logged.
  *res*, will call res.reply() to respond to client.