code: function ajaxUnit (server) {
    var ajax = server.ajax = new EventEmitter();
    // Register events to be fired before loading the ajax data.
    var ajaxReq = server.ajaxReq = new EventEmitter();
  
    return function ajaxLayer (req, res, next) {
      if (req.path[1] !== '$') { return next(); }
      var action = req.path.slice(2);
  
      if (ajax.listeners(action).length <= 0) { return next(); }
  
      res.setHeader('Content-Type', mime.json);
  
      ajaxReq.emit(action, req.ask);
      // Get all data requests.
      getQueries(req, function(err) {
        if (err == null) {
          ajax.emit(action, req.query, function ajaxEnd(data) {
            res.compressed().end(JSON.stringify(data || {}));
          }, req.ask);
        } else {
          log('While parsing', req.url + ':\n'
            + err
            , 'error');
          return next();
        }
      });
    };
  }
docs: Ajax unit.