rest.rb

get 'slices/:slice_id' do
  rest_api { Slice.find_by!(name: params[:slice_id]) }
end

class Slice
  def self.find_by!(query)
    # ...
    remote_klass =
      Trema.trema_process('RoutingSwitch', socket_dir).controller.slice
    remote_klass.find_by!(query)
  end
end