When using a smart card on a desktop client, the Sun Ray server must identify the smart card type being used and extract a unique identifier from the card. The smart card types are identified through smart card configuration files, which are written in the SwapDrop language and located in the: /etc/opt/SUNWut/smartcard directory. All files end with a .cfg suffix, as in, acme_card.cfg.

When a user inserts a smart card into a desktop client, the available smart card configuration files are run in order based on the smart card probe order, as described in Section 8.4, “Smart Card Probe Order”. When run, the configuration file performs an I/O action with the smart card to try to identify it.

If a configuration file identifies the smart card, a unique token ID is sent to the server and the session associated with that token ID becomes the active session connected to the client. If no configuration files can identify the card, then the Card Error icon is displayed on the client and there is no session activated for the client.