A service provider may provide one or more services to and/or for a client. Providing a service may involve receiving a service request including a security token at the service provider and determining whether the security token is valid. Providing the service may also involve determining a session security token if the security token is valid and generating a service response including the session security token. Providing the service may further involve receiving a service request including the session security token, determining whether the session security token is valid, and, if the session security token is valid, generating a second service response.