/// <summary>
        /// Timer work: Check if there is any failed (expired) sessions
        /// </summary>
        /// <param name="state"></param>
        private void DoWork(object state)
        {
            var session = sessionRepository.GetOldestSession().Result;

            if (session != null && session.Expire < DateTime.Now.Ticks)
            {
                sessionRepository.AddFailedSession(session);
                sessionRepository.DeleteSession(session.SessionId);
            }
        }