Logging in works, too.

php <<'EOF'
<?php
include "OSRFGatewayClient.php";
$credentials = [ "username" => "admin", "password" => "demo123", "type" => "staff" ];
$client = new OSRFGatewayClient("jammy.cwmars.org");
$request = new OSRFRequest("open-ils.auth", "open-ils.auth.login", $credentials);
$respons = $client->request($request);
print_r($respons);
EOF
stdClass Object
(
    [payload] => Array
        (
            [0] => stdClass Object
                (
                    [ilsevent] => 0
                    [textcode] => SUCCESS
                    [desc] => Success
                    [pid] => 1896
                    [stacktrace] => oils_auth.c:636
                    [payload] => stdClass Object
                        (
                            [authtoken] => c723db268bbfaa4cd923c354b1f41f48
                            [authtime] => 7200
                        )

                )

        )

    [status] => 200
)