serve

# File actionpack/lib/action_dispatch/journey/router.rb, line 30
      def serve(req)
        recognize(req) do |route, parameters|
          req.path_parameters = parameters
          req.route = route

          _, headers, _ = response = route.app.serve(req)

          return response unless headers[Constants::X_CASCADE] == "pass"
        end

        [404, { Constants::X_CASCADE => "pass" }, ["Not Found"]]
      end