This Article 
 Bibliographic References 
 Add to: 
Dynamic QoS Management and Optimization in Service-Based Systems
May/June 2011 (vol. 37 no. 3)
pp. 387-409
Radu Calinescu, Aston University, Birmingham
Lars Grunske, Swinburne University of Technology, Swinburne
Marta Kwiatkowska, Oxford University Computing Laboratories, Oxford
Raffaela Mirandola, Politecnico di Milano, Milano
Giordano Tamburrelli, Politecnico di Milano, Milano
Service-based systems that are dynamically composed at runtime to provide complex, adaptive functionality are currently one of the main development paradigms in software engineering. However, the Quality of Service (QoS) delivered by these systems remains an important concern, and needs to be managed in an equally adaptive and predictable way. To address this need, we introduce a novel, tool-supported framework for the development of adaptive service-based systems called QoSMOS (QoS Management and Optimization of Service-based systems). QoSMOS can be used to develop service-based systems that achieve their QoS requirements through dynamically adapting to changes in the system state, environment, and workload. QoSMOS service-based systems translate high-level QoS requirements specified by their administrators into probabilistic temporal logic formulae, which are then formally and automatically analyzed to identify and enforce optimal system configurations. The QoSMOS self-adaptation mechanism can handle reliability and performance-related QoS requirements, and can be integrated into newly developed solutions or legacy systems. The effectiveness and scalability of the approach are validated using simulations and a set of experiments based on an implementation of an adaptive service-based system for remote medical assistance.

[1] R. Alur, C. Courcoubetis, and D. Dill, "Model-Checking in Dense Real-Time," Information and Computation, vol. 104, no. 1, pp. 2-34, 1993.
[2] R. Alur and T.A. Henzinger, "Reactive Modules," Formal Methods in System Design, pp. 207-218, IEEE CS Press, 1999.
[3] D. Ardagna, C. Ghezzi, and R. Mirandola, "Rethinking the Use of Models in Software Architecture," Proc. Fourth Int'l Conf. Quality of Software-Architectures, pp. 1-27, 2008.
[4] D. Ardagna and B. Pernici, "Global and Local QoS Constraints Guarantee in Web Service Selection," Proc. IEEE Int'l Conf. Web Services, pp. 805-806, 2005.
[5] D. Ardagna and B. Pernici, "Adaptive Service Composition in Flexible Processes," IEEE Trans. Software Eng., vol. 33, no. 6, pp. 369-384, June 2007.
[6] A. Aziz, V. Singhal, and F. Balarin, "It Usually Works: The Temporal Logic of Stochastic Systems," Proc. Seventh Int'l Conf. Computer Aided Verification, P. Wolper, ed., pp. 155-165, 1995.
[7] E. Badidi, L. Esmahi, and M.A. Serhani, "A Queuing Model for Service Selection of Multi-Classes QoS-Aware Web Services," Proc. IEEE Int'l Conf. Web Services, pp. 204-213, 2005.
[8] C. Baier, J.-P. Katoen, and H. Hermanns, "Approximate Symbolic Model Checking of Continuous-Time Markov Chains," Proc. 10th Int'l Conf. Concurrency Theory, J.C.M. Baeten and S. Mauw, eds., pp. 146-161, 1999.
[9] L. Baresi, D. Bianculli, C. Ghezzi, S. Guinea, and P. Spoletini, "A Timed Extension of WSCoL," Proc. IEEE Int'l Conf. Web Services, pp. 663-670, 2007.
[10] L. Baresi, D. Bianculli, C. Ghezzi, S. Guinea, and P. Spoletini, "Validation of Web Service Compositions," IET Software, vol. 1, no. 6, pp. 219-232, Dec. 2007.
[11] L. Baresi and S. Guinea, "Towards Dynamic Monitoring of WS-BPEL Processes," Proc. Third Int'l Conf. Service Oriented Computing, 2005.
[12] L. Baresi, E.D. Nitto, and C. Ghezzi, "Toward Open-World Software: Issue and Challenges," Computer, vol. 39, no. 10, pp. 36-43, Oct. 2006.
[13] R. Berbner, M. Spahn, N. Repp, O. Heckmann, and R. Steinmetz, "Heuristics for QoS-Aware Web Service Composition," Proc. IEEE Int'l Conf. Web Services, pp. 72-82, 2006.
[14] J.O. Berger, Statistical Decision Theory and Bayesian Analysis, second ed. Springer, 1985.
[15] C. Bettini, D. Maggiorini, and D. Riboni, "Distributed Context Monitoring for the Adaptation of Continuous Services," World Wide Web, vol. 10, no. 4, pp. 503-528, 2007.
[16] A. Bianco and L. de Alfaro, "Model Checking of Probabilistic and Nondeterministic Systems," Proc. 15th Conf. Foundations of Software Technology and Theoretical Computer Science, P.S. Thiagarajan, ed., pp. 499-513, 1995.
[17] D. Bianculli and C. Ghezzi, "Monitoring Conversational Web Services," Proc. Second Int'l Workshop Service Oriented Software Eng., pp. 15-21, 2007.
[18] G. Bolch, S. Greiner, H. de Meer, and K.S. Trivedi, Queuing Network and Markov Chains. John Wiley, 1998.
[19] B. Boonea, S. Van Hoeckea, G. Van Seghbroecka, N. Jonckheereb, V. Jonckersb, F.D. Turcka, C. Develdera, and B. Dhoedta, "SALSA: QoS-Aware Load Balancing for Autonomous Service Brokering," J. Systems and Software, vol. available online, p. in print, 2010.
[20] R. Calinescu, "General-Purpose Autonomic Computing," Autonomic Computing and Networking, M.K. Denko, L.T. Yang, and Y. Zhang, eds., pp. 3-30, Springer, 2009.
[21] R. Calinescu, "Reconfigurable Service-Oriented Architecture for Autonomic Computing," Int'l J. Advances in Intelligent Systems, vol. 2, no. 1, pp. 38-57, June 2009.
[22] R. Calinescu and M. Kwiatkowska, "CADS∗: Computer-Aided Development of Self-∗ Systems," Fundamental Approaches to Software Eng., M. Chechik and M. Wirsing, eds., pp. 421-424, Springer, Mar. 2009.
[23] R. Calinescu and M.Z. Kwiatkowska, "Using Quantitative Analysis to Implement Autonomic IT Systems," Proc. 31st Int'l Conf. Software Eng., pp. 100-110, 2009.
[24] G. Canfora, M. Di Penta, R. Esposito, and M.L. Villani, "An Approach for QoS-Aware Service Composition Based on Genetic Algorithms," Proc. Conf. Genetic and Evolutionary Computation, pp. 1069-1075, 2005.
[25] G. Canfora, M.D. Penta, R. Esposito, and M.L. Villani, "QoS-Aware Replanning of Composite Web Services," Proc. IEEE Int'l Conf. Web Services, pp. 121-129, 2005.
[26] G. Canfora, M.D. Penta, R. Esposito, and M.L. Villani, "A Framework for QoS-Aware Binding and Re-Binding of Composite Web Services," J. Systems and Software, vol. 81, no. 10, pp. 1754-1769, 2008.
[27] L. Cao, J. Cao, and M. Li, "Genetic Algorithm Utilized in Cost-Reduction Driven Web Service Selection," Proc. Int'l Conf. Computational Intelligence and Security, Y. Hao, J. Liu, Y. Wang, Y.M. Cheung, H. Yin, L. Jiao, J. Ma, and Y.-C. Jiao, eds., pp. 679-686, 2005.
[28] V. Cardellini, E. Casalicchio, V. Grassi, F. Lo Presti, and R. Mirandola, "QoS-Driven Runtime Adaptation of Service Oriented Architectures," Proc. European Software Eng. Conf. and ACM SIGSOFT Symp. Foundations of Software Eng., pp. 131-140, 2009.
[29] V. Cardellini, E. Casalicchio, V. Grassi, and R. Mirandola, "A Framework for Optimal Service Selection in Broker-Based Architectures with Multiple QoS Classes," Proc. Services Computing Workshops, pp. 105-112, 2006.
[30] V. Cardellini, E. Casalicchio, V. Grassi, and F.L. Presti, "Scalable Service Selection for Web Service Composition Supporting Differentiated QoS Classes," Technical Report RR-07.59, Dip. di Informatica, Sistemi e Produzione, Univ. di Roma Tor Vergata, 2007.
[31] G. Chafle, P. Doshi, J. Harney, S. Mittal, and B. Srivastava, "Improved Adaptation of Web Service Compositions Using Value of Changed Information," Proc. IEEE Conf. Web Services, pp. 784-791, 2007.
[32] B.H.C. Cheng, H. Giese, P. Inverardi, J. Magee, and R. de Lemos, "08031—Software Engineering for Self-Adaptive Systems: A Research Road Map," Software Eng. for Self-Adaptive Systems, Springer-Verlag, 2008.
[33] F. Ciesinski and M. Größer, "On Probabilistic Computation Tree Logic," Validation of Stochastic Systems—A Guide to Current Research, C. Baier, B.R. Haverkort, H. Hermanns, J.-P. Katoen, and M. Siegle, eds., pp. 147-188, Springer, 2004.
[34] A. Clark, S. Gilmore, J. Hillston, and M. Tribastone, "Stochastic Process Algebras," Seventh Int'l School Formal Methods, pp. 132-179, Springer, 2007.
[35] M. Colombo, E. Di Nitto, M. Mauri, "Scene: A Service Composition Execution Environment Supporting Dynamic Changes Disciplined through Rules," Lecture Notes in Computer Science, vol. 4294, pp. 191-202, Springer, 2006.
[36] R. Colvin, L. Grunske, and K. Winter, "Probabilistic Timed Behavior Trees," Proc. Int'l Conf. Integrated Formal Methods, J. Davies and J. Gibbons, eds., pp. 156-175, 2007.
[37] R. Colvin, L. Grunske, and K. Winter, "Timed Behavior Trees for Failure Mode and Effects Analysis of Time-Critical Systems," J. Systems and Software, vol. 81, no. 12, pp. 2163-2182, 2008.
[38] A. Dan, D. Davis, R. Kearney, A. Keller, R. King, D. Kuebler, H. Ludwig, M. Polan, M. Spreitzer, and A. Youssef, "Web Services on Demand: WSLA-Driven Automated Management," IBM Systems J., vol. 43, no. 1, pp. 136-158, 2004.
[39] M.B. Dwyer, G.S. Avrunin, and J.C. Corbett, "Property Specification Patterns for Finite-State Verification," Proc. 21st Int'l Conf. Software Eng., pp. 411-420, 1999.
[40] I. Epifani, C. Ghezzi, R. Mirandola, and G. Tamburrelli, "Model Evolution by Runtime Parameter Adaptation," Proc. 31st Int'l Conf. Software Eng., pp. 111-121, 2009.
[41] R. Frei, G.D.M. Serugendo, and J. Barata, "Designing Self-Organization for Evolvable Assembly Systems," Proc. Second IEEE Int'l Conf. Self-Adaptive and Self-Organizing Systems, pp. 97-106, 2008.
[42] S. Frolund and J. Koistinen, "Quality-of-Service Specification in Distributed Object Systems," Distributed Systems Eng. J., vol. 5, no. 4, pp. 179-202, Dec. 1998.
[43] S. Gallotti, C. Ghezzi, R. Mirandola, and G. Tamburrelli, "Quality Prediction of Service Compositions through Probabilistic Model Checking," Proc. Fourth Int'l Conf. Quality of Software-Architectures, S. Becker, F. Plasil, and R. Reussner, eds., pp. 119-134, 2008.
[44] R. Garcia, J. Jarvi, A. Lumsdaine, J. Siek, and J. Willcock, "A Comparative Study of Language Support for Generic Programming," ACM SIGPLAN Notices, vol. 38, no. 11, pp. 115-134, Nov. 2003.
[45] C. Ghezzi and G. Tamburrelli, "Predicting Performance Properties for Open Systems with KAMI," Proc. Fifth Int'l Conf. Quality of Software Architectures, pp. 70-85, 2009.
[46] S. Gilmore and J. Hillston, "The PEPA Workbench: A Tool to Support a Process Algebra-Based Approach to Performance Modelling," Proc. Seventh Int'l Conf. Computer Performance Evaluation, Modeling Techniques and Tools, G. Haring and G. Kotsis, eds., pp. 353-368, 1994.
[47] V. Grassi, "Architecture-Based Reliability Prediction for Service-Oriented Computing," Proc. Workshop Architecting Dependable Systems, pp. 279-299, 2004.
[48] V. Gruhn and R. Laue, "Patterns for Timed Property Specifications," Electronic Notes in Theoretical Computer Science, vol. 153, no. 2, pp. 117-133, 2006.
[49] L. Grunske, "Specification Patterns for Probabilistic Quality Properties," Proc. 30th Int'l Conf. Software Eng., Robby, ed., pp. 31-40, 2008.
[50] L. Grunske, K. Winter, and R. Colvin, "Timed Behavior Trees and Their Application to Verifying Real-Time Systems," Proc. Australian Software Eng. Conf., pp. 211-222, 2007.
[51] L. Grunske and P. Zhang, "Monitoring Probabilistic Properties," Proc. Seventh Joint Meeting of the European Software Eng. Conf. and the ACM SIGSOFT Int'l Symp. Foundations of Software Eng., H. van Vliet and V. Issarny, eds., pp. 183-192, 2009.
[52] H. Guo, J. Huai, H. Li, T. Deng, Y. Li, and Z. Du, "ANGEL: Optimal Configuration for High Available Service Composition," IEEE Int'l Conf. Web Services, pp. 280-287, 2007.
[53] H. Hansson and B. Jonsson, "A Logic for Reasoning about Time and Reliability," Formal Aspects of Computing, vol. 6, no. 5, pp. 512-535, 1994.
[54] D. Harel and R. Marelly, "Playing with Time: On the Specification and Execution of Time-Enriched LSCs," Proc. 10th Int'l Workshop Modeling, Analysis, and Simulation of Computer and Telecomm. Systems, pp. 193-202, 2002.
[55] J. Harney and P. Doshi, "Speeding Up Adaptation of Web Service Compositions Using Expiration Times," Proc. Int'l Conf. World Wide Web, pp. 1023-1032, 2007.
[56] M.C. Huebscher and J.A. McCann, "A Survey of Autonomic Computing—Degrees, Models, and Applications," ACM Computing Surveys, vol. 40, no. 3, pp. 1-28, 2008.
[57] D. Hull, K. Wolstencroft, R. Stevens, C. Goble, M. Pocock, P. Li, and T. Oinn, "Taverna: A Tool for Building and Running Workflows of Services," Nucleic Acids Research, vol. 34, no. Web Server issue, pp. 729-732, July 2006.
[58] ITU-TS, "ITU-TS Recommendation Z.120: Message Sequence Chart 1999 (MSC99)," technical report, Int'l Telecomm. Union (ITU-TS), 1999.
[59] D.N. Jansen, H. Hermanns, and J.-P. Katoen, "A Probabilistic Extension of UML Statecharts," Proc. Seventh Int'l Symp. Formal Techniques in Real-Time and Fault-Tolerant Systems, W. Damm and E.-R. Olderog, eds., pp. 355-374, 2002.
[60] D.N. Jansen, H. Hermanns, and J.-P. Katoen, "A QoS-Oriented Extension of UML Statecharts," Proc. Sixth Int'l Conf.—The Unified Modeling Language. Model Languages and Applications, P. Stevens, J. Whittle, and G. Booch, eds., pp. 76-91, 2003.
[61] D.N. Jansen, J.-P. Katoen, M. Oldenkamp, M. Stoelinga, and I. Zapreev, "How Fast and Fat Is Your Probabilistic Model Checker? An Experimental Comparison," Hardware and Software: Verification and Testing, K. Yorav, ed., pp. 69-85, Springer, 2008.
[62] M.B. Juric, B. Mathew, and P. Sarang, Business Process Execution Language for Web Services. Packt Publishing, 2004.
[63] D. Karastoyanova and F. Leymann, "BPEL'n'Aspects: Adapting Service Orchestration Logic," Proc. IEEE Int'l Conf. Web Services, pp. 222-229, 2009.
[64] J.-P. Katoen, T. Kemna, I.S. Zapreev, and D.N. Jansen, "Bisimulation Minimisation Mostly Speeds Up Probabilistic Model Checking," Proc. Int'l Conf. Tools and Algorithms for the Construction and Analysis of Systems, O. Grumberg and M. Huth, eds., pp. 87-101, 2007.
[65] A. Keller and H. Ludwig, "The WSLA Framework: Specifying and Monitoring Service Level Agreements for Web Services," J. Network and Systems Management, vol. 11, no. 1, pp. 57-81, 2003.
[66] J.O. Kephart and D.M. Chess, "The Vision of Autonomic Computing," Computer, vol. 36, no. 1, pp. 41-50, Jan. 2003.
[67] J.M. Ko, C.O. Kim, and I.-H. Kwon, "Quality-of-Service Oriented Web Service Composition Algorithm and Planning Architecture," J. Systems and Software, vol. 81, no. 11, pp. 2079-2090, 2008.
[68] S. Konrad and B.H.C. Cheng, "Real-Time Specification Patterns," Proc. 27th Int'l Conf. Software Eng., G.-C. Roman, W.G. Griswold, and B. Nuseibeh, eds., pp. 372-381, 2005.
[69] R. Koymans, "Specifying Real-Time Properties with Metric Temporal Logic," Real-Time Systems, vol. 2, no. 4, pp. 255-299, 1990.
[70] J. Kramer and J. Magee, "Self-Managed Systems: An Architectural Challenge," Proc. Future of Software Eng., pp. 259-268, 2007.
[71] M.Z. Kwiatkowska, G. Norman, D. Parker, and J. Sproston, "Performance Analysis of Probabilistic Timed Automata Using Digital Clocks," Formal Methods in System Design, vol. 29, no. 1, pp. 33-78, 2006.
[72] M.Z. Kwiatkowska, G. Norman, and D. Parker, "Probabilistic Symbolic Model Checking with PRISM: A Hybrid Approach," Int'l J. Software Tools for Technology Transfer, vol. 6, no. 2, pp. 128-142, Aug. 2004.
[73] M.Z. Kwiatkowska, G. Norman, and D. Parker, "Symmetry Reduction for Probabilistic Model Checking," Proc. 18th Int'l Conf. Computer Aided Verification, T. Ball and R.B. Jones, eds., pp. 234-248, 2006.
[74] M.Z. Kwiatkowska, G. Norman, J. Sproston, and F. Wang, "Symbolic Model Checking for Probabilistic Timed Automata," Information and Computation, vol. 205, no. 7, pp. 1027-1077, 2007.
[75] D.D. Lamanna, J. Skene, and W. Emmerich, "Slang: A Language for Defining Service Level Agreements," Proc. Ninth IEEE Int'l Workshop Future Trends of Distributed Computing Systems, pp. 100-107, 2003.
[76] E.D. Lazowska, J. Zahorjan, G.S. Graham, and K.C. Sevcik, Quantitative System Performance: Computer System Analysis Using Queueig Network Models. Prentice-Hall, 1984.
[77] Y. Ma and C. Zhang, "Quick Convergence of Genetic Algorithm for QoS-Driven Web Service Selection," Computer Networks, vol. 52, no. 5, pp. 1093-1104, 2008.
[78] M.A. Marsan, "Stochastic Petri Nets: An Elementary Introduction," Advances in Petri Nets, pp. 1-29, Springer, June 1989.
[79] M. Marzolla and R. Mirandola, "Performance Prediction of Web Service Workflows," Proc. Int'l Conf. Quality of Software Architectures, pp. 127-144, 2007.
[80] D.A. Menascé, E. Casalicchio, and V. Dubey, "A Heuristic Approach to Optimal Service Selection in Service Oriented Architectures," Proc. Seventh Int'l Workshop Software and Performance, A. Avritzer, E.J. Weyuker, and C.M. Woodside, eds., pp. 13-24, 2008.
[81] D.A. Menascé and V. Dubey, "Utility-Based QoS Brokering in Service Oriented Architectures," Proc. Int'l Conf. Web Services, pp. 422-430, 2007.
[82] D.A. Menascé, J.M. Ewing, H. Gomaa, S. Malek, and J.P. Sousa, "A Framework for Utility-Based Service Oriented Design in SASSY," First Joint WOSP/SIPEW Int'l Conf. Performance Eng., pp. 27-36, 2010.
[83] D.A. Menascé, H. Ruan, and H. Gomaa, "QoS Management in Service-Oriented Architectures," Performance Evaluation, vol. 64, nos. 7/8, pp. 646-663, 2007.
[84] O. Moser, F. Rosenberg, and S. Dustdar, "Non-Intrusive Monitoring and Service Adaptation for WS-BPEL," Proc. Int'l Conf. World Wide Web, pp. 815-824, 2008.
[85] "myExperiment web site," (repository snapshot on), Apr. 2010.
[86] E.D. Nitto, C. Ghezzi, A. Metzger, M.P. Papazoglou, and K. Pohl, "A Journey to Highly Dynamic, Self-Adaptive Service-Based Applications," Automated Software Eng., vol. 15, nos. 3/4, pp. 313-341, 2008.
[87] T. Oinn, M. Greenwood, M. Addis, N. Alpdemir, J. Ferris, K. Glover, C. Goble, A. Goderis, D. Hull, D. Marvin, P. Li, P. Lord, M. Pocock, M. Senger, R. Stevens, A. Wipat, and C. Wroe, "Taverna: Lessons in Creating a Workflow Environment for the Life Sciences," Concurrency and Computation: Practice and Experience, vol. 18, no. 10, pp. 1067-1100, Aug. 2006.
[88] M.P. Papazoglou and W.-J. Heuvel, "Service Oriented Architectures: Approaches, Technologies and Research Issues," Int'l J. Very Large Data Bases , vol. 16, no. 3, pp. 389-415, 2007.
[89] M.L. Puterman, Markov Decision Processes. Wiley, 1994.
[90] G.N. Rodrigues, D.S. Rosenblum, and S. Uchitel, "Using Scenarios to Predict the Reliability of Concurrent Component-Based Software Systems," Proc. Eighth Int'l Conf. Fundamental Approaches to Software Eng., M. Cerioli, ed., pp. 111-126, 2005.
[91] F. Saffre, R. Tateson, J. Halloy, M. Shackleton, and J.-L. Deneubourg, "Aggregation Dynamics in Overlay Networks and Their Implications for Self-Organized Distributed Applications," Computer J., vol. 52, pp. 397-412, 2008.
[92] A. Sahai, V. Machiraju, M. Sayal, A.P.A. van Moorsel, and F. Casati, "Automated SLA Monitoring for Web Services," Proc. 13th IFIP/IEE Int'l Workshop Distributed Systems Operations and Management, M. Feridun, P.G. Kropf, and G. Babin, eds., pp. 28-41, 2002.
[93] N. Sato and K.S. Trivedi, "Stochastic Modeling of Composite Web Services for Closed-Form Analysis of Their Performance and Reliability Bottlenecks," Proc. Int'l Conf. Service Oriented Computing, pp. 107-118, 2007.
[94] M.A. Serhani, R. Dssouli, A. Hafid, and H.A. Sahraoui, "A QoS Broker Based Architecture for Efficient Web Services Selection," Proc. IEEE Int'l Conf. Web Services, pp. 113-120, 2005.
[95] J.M. Sobel and D.P. Friedman, "An Introduction to Reflection-Oriented Programming," Proc. Reflection '96, Apr. 1996.
[96] S. Su, C. Zhang, and J. Chen, "An Improved Genetic Algorithm for Web Services Selection," Proc. Seventh IFIP WG 6.1 Int'l Conf. Distributed Application and Interoperable Systems, J. Indulska and K. Raymond, eds., pp. 284-295, 2007.
[97] T. Suto, J.T. Bradley, and W.J. Knottenbelt, "Performance Trees: A New Approach to Quantitative Performance Specification," Proc. 14th Int'l Symp. Modeling, Analysis, and Simulation of Computer and Telecomm. Systems, pp. 303-313, 2006.
[98] V. Tosic, B. Pagurek, and K. Patel, "WSOL—A Language for the Formal Specification of Classes of Service for Web Services," Proc. Int'l Conf. Web Services, L.-J. Zhang, ed., pp. 375-381, 2003.
[99] L. Wang, N.J. Dingle, and W.J. Knottenbelt, "Natural Language Specification of Performance Trees," Proc. Fifth European Performance Eng. Workshop, N. Thomas and C. Juiz, eds., pp. 141-151, 2008.
[100] H.L.S. Younes and R.G. Simmons, "Statistical Probabilistic Model Checking with a Focus on Time-Bounded Properties," Information and Computation, vol. 204, no. 9, pp. 1368-1409, 2006.
[101] L. Zeng, B. Benatallah, A.H.H. Ngu, M. Dumas, J. Kalagnanam, and H. Chang, "QoS-Aware Middleware for Web Services Composition," IEEE Trans. Software Eng., vol. 30, no. 5, pp. 311-327, May 2004.
[102] C. Zhang, S. Su, and J. Chen, "DiGA: Population Diversity Handling Genetic Algorithm for QoS-Aware Web Services Selection," Computer Comm., vol. 30, no. 5, pp. 1082-1090, May 2007.

Index Terms:
Service-oriented software engineering, QoS management, QoS optimization, adaptive systems.
Radu Calinescu, Lars Grunske, Marta Kwiatkowska, Raffaela Mirandola, Giordano Tamburrelli, "Dynamic QoS Management and Optimization in Service-Based Systems," IEEE Transactions on Software Engineering, vol. 37, no. 3, pp. 387-409, May-June 2011, doi:10.1109/TSE.2010.92
Usage of this product signifies your acceptance of the Terms of Use.