docs: function proxyServerMidleware(req, res, next) {
      // Check if static resource exist
      var sfile = path.join(req.app.get('static resource'), req.path);
      if(fs.existsSync(sfile)) {
          return next();
      }
      // Proxy request
      // --------------
      // buffer so that it won't be lost,
      // !!This is confilced with `methodOverride()`
      var buffer = httpProxy.buffer(req);
      var proxySetting = req.app.get('proxy setting');
      // Do process
      ProxyInstance.proxyRequest(req, res, {
          host: proxySetting.remote.host,
          port: proxySetting.remote.port,
          buffer: buffer
      });
  }