Service-oriented architecture is becoming a major software framework for complex application and it can be dynamically and flexibly composed by integrating existing component web services provided by different provide...Service-oriented architecture is becoming a major software framework for complex application and it can be dynamically and flexibly composed by integrating existing component web services provided by different providers with standard protocols. The rapid introduction of new web services into a dynamic business environment can adversely affect the service quality and user satisfaction. Therefore, how to leverage, aggregate and make use of individual component’s quality of service (QoS) information to derive the optimal QoS of the composite service which meets the needs of users is still an ongoing hot research problem. This study aims at reviewing the advance of the current state-of-the-art in technologies and inspiring the possible new ideas for web service selection and composition, especially with nature-inspired computing approaches. Firstly, the background knowledge of web services is presented. Secondly, various nature-inspired web selection and composition approaches are systematically reviewed and analysed for QoS-aware web services. Finally, challenges, remarks and discussions about QoS-aware web service composition are presented.展开更多
In this paper, a representative set of QoS models and QoS-aware on-demand routing protocols are reviewed with emphasis on their ability to support QoS in mobile ad-hoc networks (MANETs) possibly used in WSNs. In parti...In this paper, a representative set of QoS models and QoS-aware on-demand routing protocols are reviewed with emphasis on their ability to support QoS in mobile ad-hoc networks (MANETs) possibly used in WSNs. In particular IntServ, DiffServ, FQMM, and SWAN QoS models are reviewed followed by different QoS-aware on-demand routings in MANETs from different perspectives such as the challenges, classifications, algorithmic aspects in QoS provisions. Tradeoff in providing support to real time (RT) and best effort (BE) traffic is highlighted. Finally, a detailed and comprehensive comparison table is provided for better understanding of QoS provision in MANETs.展开更多
The existing mobile service discovery approaches do not completely address the issues of service selection and the robustness faced to mobility. The infrastructure of mobile service must be QoS-aware plus context-awar...The existing mobile service discovery approaches do not completely address the issues of service selection and the robustness faced to mobility. The infrastructure of mobile service must be QoS-aware plus context-aware (i.e.) aware of the user’s required-QoS and the QoS offered by the other networks in user’s context. In this paper, we propose a cluster based QoS-aware service discovery architecture using swarm intelligence. Initially, in this architecture, the client sends a service request together with its required QoS parameters like power, distance, CPU speed etc. to its source cluster head. Swarm intelligence is used to establish the intra and inter cluster shortest path routing. Each cluster head searches the QoS aware server with matching QoS constraints by means of a service table and a server table. The QoS aware server is selected to process the service request and to send the reply back to the client. By simulation results, we show that the proposed architecture can attain a good success rate with reduced delay and energy consumption, since it satisfies the QoS constraints.展开更多
In the research of service composition,it demands efficient algorithms that not only retrieve correct service compositions automatically from thousands of services but also satisfy the quality requirements of differen...In the research of service composition,it demands efficient algorithms that not only retrieve correct service compositions automatically from thousands of services but also satisfy the quality requirements of different service users.However,most approaches treat these two aspects as two separate problems,automatic service composition and service selection.Although the latest researches realize the restriction of this separate view and some specific methods are proposed,they still suffer from serious limitations in scalability and accuracy when addressing both requirements simultaneously.In order to cope with these limitations and efficiently solve the combined problem which is known as QoS-aware or QoS-driven automatic service composition problem,we propose a new graph search problem,single-source optimal directed acyclic graphs （DAGs）,for the first time.This novel single-source optimal DAGs （SSOD） problem is similar to,but more general than the classical single-source shortest paths （SSSP） problem.In this paper,a new graph model of SSOD problem is proposed and a Sim-Dijkstra algorithm is presented to address the SSOD problem with the time complexity of O（n log n ＋ m） （n and m are the number of nodes and edges in the graph respectively）,and the proofs of its soundness.It is also directly applied to solve the QoS-aware automatic service composition problem,and a service composition tool named QSynth is implemented.Evaluations show that Sim-Dijkstra algorithm achieves superior scalability and efficiency with respect to a large variety of composition scenarios,even more efficient than our worklist algorithm that won the performance championship of Web Services Challenge 2009.展开更多
In Software-Defined Networks(SDNs),determining how to efficiently achieve Quality of Service(QoS)-aware routing is challenging but critical for significantly improving the performance of a network,where the metrics of...In Software-Defined Networks(SDNs),determining how to efficiently achieve Quality of Service(QoS)-aware routing is challenging but critical for significantly improving the performance of a network,where the metrics of QoS can be defined as,for example,average latency,packet loss ratio,and throughput.The SDN controller can use network statistics and a Deep Reinforcement Learning(DRL)method to resolve this challenge.In this paper,we formulate dynamic routing in an SDN as a Markov decision process and propose a DRL algorithm called the Asynchronous Advantage Actor-Critic QoS-aware Routing Optimization Mechanism(AQROM)to determine routing strategies that balance the traffic loads in the network.AQROM can improve the QoS of the network and reduce the training time via dynamic routing strategy updates;that is,the reward function can be dynamically and promptly altered based on the optimization objective regardless of the network topology and traffic pattern.AQROM can be considered as one-step optimization and a black-box routing mechanism in high-dimensional input and output sets for both discrete and continuous states,and actions with respect to the operations in the SDN.Extensive simulations were conducted using OMNeT++and the results demonstrated that AQROM 1)achieved much faster and stable convergence than the Deep Deterministic Policy Gradient(DDPG)and Advantage Actor-Critic(A2C),2)incurred a lower packet loss ratio and latency than Open Shortest Path First(OSPF),DDPG,and A2C,and 3)resulted in higher and more stable throughput than OSPF,DDPG,and A2C.展开更多
基金supported by National Natural Science Foundation of China (71772060, 61873040, 61375066).
文摘Service-oriented architecture is becoming a major software framework for complex application and it can be dynamically and flexibly composed by integrating existing component web services provided by different providers with standard protocols. The rapid introduction of new web services into a dynamic business environment can adversely affect the service quality and user satisfaction. Therefore, how to leverage, aggregate and make use of individual component’s quality of service (QoS) information to derive the optimal QoS of the composite service which meets the needs of users is still an ongoing hot research problem. This study aims at reviewing the advance of the current state-of-the-art in technologies and inspiring the possible new ideas for web service selection and composition, especially with nature-inspired computing approaches. Firstly, the background knowledge of web services is presented. Secondly, various nature-inspired web selection and composition approaches are systematically reviewed and analysed for QoS-aware web services. Finally, challenges, remarks and discussions about QoS-aware web service composition are presented.
文摘In this paper, a representative set of QoS models and QoS-aware on-demand routing protocols are reviewed with emphasis on their ability to support QoS in mobile ad-hoc networks (MANETs) possibly used in WSNs. In particular IntServ, DiffServ, FQMM, and SWAN QoS models are reviewed followed by different QoS-aware on-demand routings in MANETs from different perspectives such as the challenges, classifications, algorithmic aspects in QoS provisions. Tradeoff in providing support to real time (RT) and best effort (BE) traffic is highlighted. Finally, a detailed and comprehensive comparison table is provided for better understanding of QoS provision in MANETs.
文摘The existing mobile service discovery approaches do not completely address the issues of service selection and the robustness faced to mobility. The infrastructure of mobile service must be QoS-aware plus context-aware (i.e.) aware of the user’s required-QoS and the QoS offered by the other networks in user’s context. In this paper, we propose a cluster based QoS-aware service discovery architecture using swarm intelligence. Initially, in this architecture, the client sends a service request together with its required QoS parameters like power, distance, CPU speed etc. to its source cluster head. Swarm intelligence is used to establish the intra and inter cluster shortest path routing. Each cluster head searches the QoS aware server with matching QoS constraints by means of a service table and a server table. The QoS aware server is selected to process the service request and to send the reply back to the client. By simulation results, we show that the proposed architecture can attain a good success rate with reduced delay and energy consumption, since it satisfies the QoS constraints.
基金Supported by the National Basic Research 973 Program of China under Grant No.2007CB-310805the National Natural Science Foundation of China under Grant No.61070027+2 种基金the Beijing Natural Science Foundation project under Grant No.4092043the Scienceand Technology Project of State Grid Information&Telecommunication Company Ltd.under Grant No.SGIT[2010]449the Planned Science and Technology Project of Guangdong Province,China under Grant No.2010B050100009
文摘In the research of service composition,it demands efficient algorithms that not only retrieve correct service compositions automatically from thousands of services but also satisfy the quality requirements of different service users.However,most approaches treat these two aspects as two separate problems,automatic service composition and service selection.Although the latest researches realize the restriction of this separate view and some specific methods are proposed,they still suffer from serious limitations in scalability and accuracy when addressing both requirements simultaneously.In order to cope with these limitations and efficiently solve the combined problem which is known as QoS-aware or QoS-driven automatic service composition problem,we propose a new graph search problem,single-source optimal directed acyclic graphs （DAGs）,for the first time.This novel single-source optimal DAGs （SSOD） problem is similar to,but more general than the classical single-source shortest paths （SSSP） problem.In this paper,a new graph model of SSOD problem is proposed and a Sim-Dijkstra algorithm is presented to address the SSOD problem with the time complexity of O（n log n ＋ m） （n and m are the number of nodes and edges in the graph respectively）,and the proofs of its soundness.It is also directly applied to solve the QoS-aware automatic service composition problem,and a service composition tool named QSynth is implemented.Evaluations show that Sim-Dijkstra algorithm achieves superior scalability and efficiency with respect to a large variety of composition scenarios,even more efficient than our worklist algorithm that won the performance championship of Web Services Challenge 2009.
基金fully supported by GUET Excellent Graduate Thesis Program(Grant No.19YJPYBS03)Innovation Project of Guangxi Graduate Education(Grant No.YCBZ2022109)New Technology Research University Cooperation Project of the 34th Research Institute of China Electronics Technology Group Corporation,2021(Grant No.SF2126007)。
文摘In Software-Defined Networks(SDNs),determining how to efficiently achieve Quality of Service(QoS)-aware routing is challenging but critical for significantly improving the performance of a network,where the metrics of QoS can be defined as,for example,average latency,packet loss ratio,and throughput.The SDN controller can use network statistics and a Deep Reinforcement Learning(DRL)method to resolve this challenge.In this paper,we formulate dynamic routing in an SDN as a Markov decision process and propose a DRL algorithm called the Asynchronous Advantage Actor-Critic QoS-aware Routing Optimization Mechanism(AQROM)to determine routing strategies that balance the traffic loads in the network.AQROM can improve the QoS of the network and reduce the training time via dynamic routing strategy updates;that is,the reward function can be dynamically and promptly altered based on the optimization objective regardless of the network topology and traffic pattern.AQROM can be considered as one-step optimization and a black-box routing mechanism in high-dimensional input and output sets for both discrete and continuous states,and actions with respect to the operations in the SDN.Extensive simulations were conducted using OMNeT++and the results demonstrated that AQROM 1)achieved much faster and stable convergence than the Deep Deterministic Policy Gradient(DDPG)and Advantage Actor-Critic(A2C),2)incurred a lower packet loss ratio and latency than Open Shortest Path First(OSPF),DDPG,and A2C,and 3)resulted in higher and more stable throughput than OSPF,DDPG,and A2C.
