Abstract: Derivatives of 7-alkylidene cephalosporanic acid sulfone and the pharmaceutically active salts thereof are found to be potent inhibitors of &bgr;-lactamase enzymes.

Abstract: The recovery of online sessions for directory services is disclosed. A server maintains a directory service of a plurality of clients. In one embodiment, a unique token for each client, known to the client and to the server, permits the client to relog onto the server, for example, after the client has crashed. In another embodiment, a client caches the information sent to the server during the log-on process, so that if the server in response to a later refresh request from the client cannot locate the client--as a result, for example, of a network or server crash--the client can automatically relog onto the server using the cached information, without user intervention. The message sent by the server to the client in response to a refresh request, after the client's entry in the directory no longer exists after a server or network crash, is desirably a dedicated error message instructing the client that it is not logged onto the server, and therefore that it should relog onto the server.