The Site Central Authorization Service (SCAS) will make authorization and mapping decision centrally. It uses HTTPS authentication to authenticate a client (as regular user or pilot job user) and present user credentials. The return message will contain a deny of permit decision, and when permitted Unix UID, primary GID and secondary GIDs will be returned. The primary client tool is gLExec, but the client is actually an LCMAPS plugin, so other tools like all the pre-WS GT4 gatekeepers, gridftpd and gsi-opensshd tools can also utilize this client server interaction.