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An Adaptive Quality of Service Aware Middleware for Replicated Services
November 2003 (vol. 14 no. 11)
pp. 1112-1125

Abstract—A dependable middleware should be able to adaptively share the distributed resources it manages in order to meet diverse application requirements, even when the quality of service (QoS) is degraded due to uncertain variations in load and unanticipated failures. In this paper, we have addressed this issue in the context of a dependable middleware that adaptively manages replicated servers to deliver a timely and consistent response to time-sensitive client applications. These applications have specific temporal and consistency requirements, and can tolerate a certain degree of relaxed consistency in exchange for better response time. We propose a flexible QoS model that allows clients to specify their timeliness and consistency constraints. We also propose an adaptive framework that dynamically selects replicas to service a client's request based on the prediction made by probabilistic models. These models use the feedback from online performance monitoring of the replicas to provide probabilistic guarantees for meeting a client's QoS specification. The experimental results we have obtained demonstrate the role of feedback and the efficacy of simple analytical models for adaptively sharing the available replicas among the users under different workload scenarios.

[1] K. Birman, Replication and Fault Tolerance in the ISIS System Proc. 10th ACM Symp. Operating Systems Principles, pp. 79-86, Dec. 1985.
[2] K. Birman, Building Secure and Reliable Network Applications. Manning, 1996.
[3] R. Carter and M. Crovella, Dynamic Server Selection Using Bandwidth Probing in Wide Area Networks Technical Report, Boston Univ., BU-CS-96-007, 1996.
[4] G.V. Chockler, R. Vitenberg, and R. Friedman, Consistency Conditions for a CORBA Caching Service Proc. Int'l Symp. Distributed Computing, Oct. 2000.
[5] M. Cukier et al., AQuA: An Adaptive Architecture that Provides Dependable Distributed Objects Proc. IEEE Symp. Reliable Distributed Systems, pp. 245-253, Oct. 1998.
[6] A. Demers, D. Greene, C. Hauser, W. Irish, and J. Larson, Epidemic Algorithms for Replicated Database Maintenance Proc. ACM Symp. Principles of Distributed Computing, pp. 1-12, 1987.
[7] Z. Fei, S. Bhattacharjee, E. Zegura, and M. Ammar, A Novel Server Selection Technique for Improving the Response Time of a Replicated Service Proc. IEEE INFOCOM, Mar. 1998.
[8] R. Golding, A Weak-Consistency Architecture for Distributed Information Services Computing Systems, vol. 5, no. 4, pp. 379-405, 1992.
[9] R. Guerraoui and A. Schiper, Software-Based Replication for Fault Tolerance Computer, pp. 68-74, Apr. 1997.
[10] M. Harchol-Balter, M. Crovella, and C. Murta, On Choosing a Task Assignment Policy for a Distributed Server System Proc. Performance Tools Conf., pp. 231-242, Sept. 1998.
[11] M. Hayden, The Ensemble System PhD thesis, Cornell Univ., Jan. 1998.
[12] N. Johnson, S. Kotz, and A. Kemp, Univariate Discrete Distributions. chapter 3, second ed., pp. 129-130, Addison-Wesley, 1992.
[13] B. Kantor and P. Rapsey, Network News Transfer Protocol , Feb. 1986.
[14] S. Krishnamurthy, W.H. Sanders, and M. Cukier, A Dynamic Replica Selection Algorithm for Tolerating Timing Faults Proc. Int'l Conf. Dependable Systems and Networks, pp. 107-116, July 2001.
[15] S. Krishnamurthy, W.H. Sanders, and M. Cukier, An Adaptive Framework for Tunable Consistency and Timeliness Using Replication Proc. Int'l Conf. Dependable Systems and Networks, pp. 17-26, June 2002.
[16] S. Krishnamurthy, W.H. Sanders, and M. Cukier, Performance Evaluation of a Probabilistic Replica Selection Algorithm Proc. Workshop Object-Oriented Real-Time Dependable Systems, pp. 119-127, Jan. 2002.
[17] S. Krishnamurthy, W.H. Sanders, and M. Cukier, Performance Evaluation of a QoS-Aware Framework for Providing Tunable Consistency and Timeliness Proc. Int'l Workshop Quality of Service, pp. 214-223, May 2002.
[18] V. Krishnaswamy, M. Raynal, D. Bakken, and M. Ahamad, Shared State Consistency for Time-Sensitive Distributed Applications Proc. Int'l Conf. Distributed Computing Systems, pp. 606-614, Apr. 2001.
[19] L. Lamport, Time, Clocks, and the Ordering of Events in Distributed Systems Comm. ACM, vol. 21, no. 7, pp. 558-565, July 1978.
[20] M. Little, Object Replication in a Distributed System PhD thesis, Univ. of Newcastle upon Tyne, Sept. 1991.
[21] L. Moser, P. Melliar-Smith, and P. Narasimhan, A Fault Tolerance Framework for CORBA Proc. IEEE Int'l Symp. Fault-Tolerant Computing, pp. 150-157, June 1999.
[22] K. Petersen, M. Spreitzer, D. Terry, M. Theimer, and A. Demers, Flexible Update Propagation for Weakly Consistent Replication Proc. 16th ACM Symp. Operating Systems Principles, pp. 288-301, Oct. 1997.
[23] C. Pu and A. Leff, Replica Control in Distributed Systems: An Asynchronous Approach Proc. ACM SIGMOD Int'l Conf. Management of Data, pp. 377-386, May 1991.
[24] Y.(J.) Ren, T. Courtney, M. Cukier, C. Sabnis, W.H. Sanders, M. Seri, D.A. Karr, P. Rubel, R.E. Schantz, and D.E. Bakken, AQuA: An Adaptive Architecture that Provides Dependable Distributed Objects IEEE Trans. Computers, vol. 52, no. 1, pp. 31-50, Jan. 2003.
[25] P. Rubel, Passive Replication in the AQuA System Master's thesis, Univ. of Illinois at Urbana-Champaign, 2000.
[26] D. Terry, Towards a Quality of Service Model for Replicated Data Access Proc. Second Int'l Workshop Services in Distributed and Networked Environments, pp. 118-122, June 1995.
[27] D. Terry, A. Demers, K. Petersen, M. Spreitzer, M. Theimer, and B. Welch, Session Guarantees for Weakly Consistent Replicated Data Proc. Int'l Conf. Parallel and Distributed Information Systems, pp. 140-149, Sept. 1994.
[28] F. Torres-Rojas, M. Ahamad, and M. Raynal, Timed Consistency for Shared Distributed Objects Proc. ACM Symp. Principles of Distributed Computing, pp. 163-172, May 1999.
[29] A. Vaysburd, Building Reliable Interoperable Distributed Applications with Maestro Tools PhD thesis, Cornell Univ., May 1998.
[30] H. Yu and A. Vahdat, Design and Evaluation of a Continuous Consistency Model for Replicated Services Proc. Fourth Symp. Operating Systems Design and Implementation, Oct. 2000.

Index Terms:
Replica consistency, middleware, quality of service, timeliness, probabilistic modeling.
Sudha Krishnamurthy, William H. Sanders, Michel Cukier, "An Adaptive Quality of Service Aware Middleware for Replicated Services," IEEE Transactions on Parallel and Distributed Systems, vol. 14, no. 11, pp. 1112-1125, Nov. 2003, doi:10.1109/TPDS.2003.1247672
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