AQuA Overview
 

Distributed systems are difficult to build. This is particularly true if they have dependability requirements that change during the execution of an application, and are built with commercial off-the-shelf hardware. In that case, fault tolerance can be achieved using middleware software, and mechanisms can be provided to communicate the dependability requirements of a distributed application to the system and to adapt the system's configuration to try to achieve the desired dependability.

The AQuA architecture allows distributed applications to request a desired level of dependability using the Quality Objects (QuO) framework and includes a dependability manager that attempts to meet requested dependability levels by configuring the system in response to outside requests and changes in system resources due to faults. The AQuA architecture uses QuO to process and invoke dependability requests, the Proteus dependability manager to configure the system in response to faults and dependability requests, and Ensemble to provide group communication services.

Furthermore, a CORBA interface is provided to application objects using the AQuA gateway. The gateway provides a mechanism to translate between process level communication, as supported by Ensemble, and IIOP messages, understood by Object Request Brokers. Both active replication and passive replication are supported for tolerating crash failures and application value failures, and the replication type to use is chosen based on performance and dependability requirements of particular distributed applications.

 

For more information: http://www.crhc.uiuc.edu/PERFORM/AQuA.html

 

Publications

Journal Publications

            J. Ren, M. Cukier, and W. H. Sanders, An Adaptive Algorithm for Tolerating Value Faults and Crash Failures, Special Issue on Dependable Network Computing in the IEEE Transactions on Parallel and Distributed Systems, vol. 12, no. 2, February 2001, pp.173-191.

            J. Ren, T. Courtney, M. Cukier, C. Sabnis, W. H. Sanders, M. Seri, D. A. Karr, P. Rubel, and R. E. Schantz, AQuA: An Adaptive Architecture that Provides Dependable Distributed Objects, to appear.

Conference Publications

            M. Cukier, J. Ren, C. Sabnis, D. Henke, J. Pistole, W. H. Sanders, D. E. Bakken, M. E. Berman, D. A. Karr, and R. E. Schantz, AQuA: An Adaptive Architecture That Provides Dependable Distributed Objects, in Proc. 17th IEEE Symposium on Reliable Distributed Systems (SRDS-98), (West Lafayette, IN, USA), pp. 245-253, IEEE Computer Society Press, October 1998.

            C. Sabnis, M. Cukier, J. Ren, P. Rubel, W. H. Sanders, D. E. Bakken, and D. A. Karr, Proteus: A Flexible Infrastructure to Implement Adaptive Fault Tolerance in AQuA, in Proc. 7th IFIP Working Conf. on Dependable Computing for Critical Applications (DCCA-7), (San Jose, CA, USA), pp. 137-156, IEEE Computer Society Press, January 1999.

            M. Cukier, J. Ren, P. Rubel, D. E. Bakken, and D. A. Karr, Building Dependable Distributed Objects with the AQuA Architecture, in Digest of FastAbstracts presented at the 29th Annual International Symposium on Fault-Tolerant Computing (FTCS-29), (Madison, WI, USA), pp. 17-18, June 1999.

            J. Ren, M. Cukier, P. Rubel, W. H. Sanders, D. E. Bakken, and D. A. Karr, Building Dependable Distributed Applications Using AQuA, in Proc. 4th IEEE Symposium on High Assurance Systems Engineering (HASE'99), (Washington D.C., USA), pp. 189-196, November 1999.

            S. Krishnamurthy, W. H. Sanders, and M. Cukier, A Dynamic Replica Selection Algorithm for Tolerating Time Faults in a Replicated Service, in Proc. International Conference on Dependable Systems and Networks (DSN-2001), (Göteborg, Sweden), pp. 107-116, July 2001.

            M. Seri, T. Courtney, M. Cukier, and W. H. Sanders, An Overview of the AQuA Gateway, in Proc. of the 1st Workshop on The ACE ORB (TAO), (St. Louis, MO, USA), August 5-6, 2001, to appear.

            S. Krishnamurthy, W. H. Sanders, and M. Cukier, An Experimental Evaluation of the Responsiveness of Replica Selection Algorithms, in Proc. of the Seventh IEEE International Workshop on Object-oriented Real-time Dependable Systems (WORDS 2002), (San Diego, CA) January 7-9, 2002, pp. 119-127.

            S. Krishnamurthy, W. H. Sanders, and M. Cukier, An Adaptive Framework for Tunable Consistency and Timeliness Using Replication, in Proc. International Conference on Dependable Systems and Networks (DSN-2002), (Washington, DC, USA), June 23-26, 2002, pp. 17-26.

            S. Krishnamurthy, W. H. Sanders, and M. Cukier, Performance Evaluation of a QoS-Aware Framework for Providing Tunable Consistency and Timeliness, in Proc. Tenth International Workshop on Quality of Service (IWQoS 2002), (Miami Beach, FL, USA), May 15-17, 2002, pp. 214-223.

            M. Seri, T. Courtney, M. Cukier, V. Gupta, S. Krishnamurthy, J. Lyons, H. Ramasamy, J. Ren, and W. H. Sanders, A Configurable CORBA Gateway for Providing Adaptable System Properties, in Supplemental Volume of the 2002 International Conference on Dependable Systems & Networks (DSN-2002), Washington, DC, June 23-26, 2002, pp. G-26 to G-30.

            Y. (J.) Ren, P. Rubel, M. Seri, M. Cukier, W. H. Sanders, and T. Courtney, Passive Replication Schemes in AQuA, in Proc. 2002 Pacific Rim International Symposium on Dependable Computing (PRDC2002), Tsukuba, Japan, December 16-18, 2002, to appear.