The [SessionSetupWebServerMiddleware] will look up [HTTPSession]s for a particular request using the stored session id. The [SessionSetupWebServerMiddleware] will look up [HTTPSession]s for a particular request from the stored session id automatically. It will take session id ([code]session_id[/code] key) from a request's cookie (if exists), and it will set the HTTPSession belonging to that id to the Request's session variable. Note that it will not create sessions automatically.