Maintaining consistency of the security policy using timestamp ordering

In this paper we propose an invalidation-based consistency protocol using timestamp ordering for concurrency control. The protocol works for a system composed of a security server and object managers located on different machines. The security server defines the security policy in a small database and object managers enforce the policy replicated on each machine. Thus, the system can be modeled as a replicated database. Since transient inconsistency among replicas may lead to unauthorized accesses, our goal of consistency is one-copy serializability (1SR) because it guarantees a one-copy view of the security policy regardless of which copy is accessed. However the requirement for good performance is also desirable. We evaluate the performance of the proposed protocol and compare it with the performance of the transactional consistency protocol, an invalidation-based consistency protocol based on a locking mechanism. Both protocols guarantee 1SR consistency. The results show that both protocols demonstrate compatible performance. However the proposed protocol offers 1SR consistency with less overhead.