function onReceive(responseCode as Lang.Number, data as Lang.Dictionary or Lang.String or Null) as Void {
        System.println("onReceive: response code: " + responseCode + ", data: " + data);
        if (responseCode == 200) {
            if (data["payload"] != null && data["payload"] instanceof Lang.Array) {
                for (var i = 0; i < data["payload"].size(); i++) {
                    var payloadItem = data["payload"][i];
                    if (payloadItem instanceof Lang.Dictionary && "temperature".equals(payloadItem["par"])) {
                        var val = payloadItem["val"];
                        if (val instanceof Lang.String) {
                            // Convert string to float. If conversion fails, null will be returned
                            var valAsFloat = val.toFloat();
                            Background.exit(valAsFloat);
                        }
                        if (val instanceof Lang.Float) {
                            Background.exit(val);
                        }
                    }
                }
            }
        }
        Background.exit(null);
    }

    public function onTemporalEvent() as Void {
        Communications.makeWebRequest(
            "https://api.existenz.ch/apiv1/hydro/latest",
            {
                "locations" => "2030",
                "version" => "1.042",
                "parameters" => "temperature,flow" // note that %2C in ASCII is ","
            },
            {
                :method => Communications.HTTP_REQUEST_METHOD_GET,
                :responseType  => Communications.HTTP_RESPONSE_CONTENT_TYPE_JSON
            },
            method(:onReceive)
        );
    }