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Efficient algorithms for web services selection with end-to-end qos constraints
- ACM Transactions on the Web (TWEB
"... Service-Oriented Architecture (SOA) provides a flexible framework for service composition. Using standard-based protocols (such as SOAP and WSDL), composite services can be constructed by integrating atomic services developed independently. Algorithms are needed to select service components with var ..."
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Cited by 160 (1 self)
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Service-Oriented Architecture (SOA) provides a flexible framework for service composition. Using standard-based protocols (such as SOAP and WSDL), composite services can be constructed by integrating atomic services developed independently. Algorithms are needed to select service components with various QoS levels according to some application-dependent performance requirements. We design a broker-based architecture to facilitate the selection of QoS-based services. The objective of service selection is to maximize an application-specific utility function under the endto-end QoS constraints. The problem is modeled in two ways: the combinatorial model and the graph model. The combinatorial model defines the problem as a multidimension multichoice 0-1 knapsack problem (MMKP). The graph model defines the problem as a multiconstraint optimal path (MCOP) problem. Efficient heuristic algorithms for service processes of different composition structures are presented in this article and their performances are studied by simulations. We also compare the pros and cons between the two models.
An approach for QoS-aware service composition based on genetic algorithms
- In Proc. GECCO ’05
, 2005
"... Web services are rapidly changing the landscape of software engineering. One of the most interesting challenges introduced by web services is represented by Quality Of Service (QoS)–aware composition and late–binding. This allows to bind,at run–time,a service–oriented system with a set of services t ..."
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Cited by 160 (7 self)
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Web services are rapidly changing the landscape of software engineering. One of the most interesting challenges introduced by web services is represented by Quality Of Service (QoS)–aware composition and late–binding. This allows to bind,at run–time,a service–oriented system with a set of services that,among those providing the required features, meet some non–functional constraints,and optimize criteria such as the overall cost or response time. In other words, QoS–aware composition can be modeled as an optimization problem. We propose to adopt Genetic Algorithms to this aim. Genetic Algorithms,while being slower than integer programming,represent a more scalable choice,and are more suitable to handle generic QoS attributes. The paper describes our approach and its applicability,advantages and weaknesses,discussing results of some numerical simulations.
Toward Autonomic Web Services Trust and Selection
, 2004
"... Emerging Web services standards enable the development of large-scale applications in open environments. In particular, they enable services to be dynamically bound. However, current techniques fail to address the critical problem of selecting the right service instances. Service selection should be ..."
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Cited by 107 (3 self)
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Emerging Web services standards enable the development of large-scale applications in open environments. In particular, they enable services to be dynamically bound. However, current techniques fail to address the critical problem of selecting the right service instances. Service selection should be determined based on user preferences and business policies, and consider the trustworthiness of service instances. We propose a multiagent approach that naturally provides a solution to the selection problem. This approach is based on an architecture and programming model in which agents represent applications and services. The agents support considerations of semantics and quality of service (QoS). They interact and share information, in essence creating an ecosystem of collaborative service providers and consumers. Consequently, our approach enables applications to be dynamically configured at runtime in a manner that continually adapts to the preferences of the participants. Our agents are designed using decision theory and use ontologies. We evaluate our approach through simulation experiments.
Combining Global Optimization with Local Selection for Efficient QoS-aware Service Composition
- In Proc. 18th Int. Conf. on World Wide Web
, 2009
"... ABSTRACT The run-time binding of web services has been recently put forward in order to support rapid and dynamic web service compositions. With the growing number of alternative web services that provide the same functionality but differ in quality parameters, the service composition becomes a dec ..."
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Cited by 84 (1 self)
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ABSTRACT The run-time binding of web services has been recently put forward in order to support rapid and dynamic web service compositions. With the growing number of alternative web services that provide the same functionality but differ in quality parameters, the service composition becomes a decision problem on which component services should be selected such that user's end-to-end QoS requirements (e.g. availability, response time) and preferences (e.g. price) are satisfied. Although very efficient, local selection strategy fails short in handling global QoS requirements. Solutions based on global optimization, on the other hand, can handle global constraints, but their poor performance renders them inappropriate for applications with dynamic and realtime requirements. In this paper we address this problem and propose a solution that combines global optimization with local selection techniques to benefit from the advantages of both worlds. The proposed solution consists of two steps: first, we use mixed integer programming (MIP) to find the optimal decomposition of global QoS constraints into local constraints. Second, we use distributed local selection to find the best web services that satisfy these local constraints. The results of experimental evaluation indicate that our approach significantly outperforms existing solutions in terms of computation time while achieving close-tooptimal results.
Bootstrapping performance and dependability attributes of web services
- In Proceedings of the IEEE International Conference on Web Services (ICWS’06
, 2006
"... Recently, Web services gain momentum for developing flexible service-oriented architectures. Quality of service (QoS) issues are currently not part of the Web service standard stack, although non-functional attributes like performance, dependability or cost and payment play an important role for ser ..."
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Cited by 75 (37 self)
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Recently, Web services gain momentum for developing flexible service-oriented architectures. Quality of service (QoS) issues are currently not part of the Web service standard stack, although non-functional attributes like performance, dependability or cost and payment play an important role for service discovery, selection, and composition. A lot of research is dedicated to different QoS models, at the same time omitting a way to specify how QoS parameters (esp. the performance related aspects) are assessed, evaluated and constantly monitored. Our contribution in this paper comprises a) an evaluation approach for QoS attributes of Web services, which works completely serviceand provider independent, b) a method to analyze Web service interactions by using our evaluation tool and extract important QoS information without any knowledge about the service implementation. Furthermore, our implementation allows assessing performance specific values (such as latency or service processing time) that usually require access to the server which hosts the service. The result of the evaluation process can be used to enrich existing Web service descriptions with a set of up-to-date QoS attributes, therefore, making it a valuable instrument for Web service selection. 1.
I.: A qos-aware selection model for semantic web services
- In: ICSOC
, 2006
"... Abstract. Automating Service Oriented Architectures by augmenting them with semantics will form the basis of the next generation of computing. Selection of service still is an important challenge, especially, when a set of services fulfilling user’s capabilities requirements have been discovered, am ..."
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Cited by 60 (2 self)
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Abstract. Automating Service Oriented Architectures by augmenting them with semantics will form the basis of the next generation of computing. Selection of service still is an important challenge, especially, when a set of services fulfilling user’s capabilities requirements have been discovered, among these services which one will be eventually invoked by user is very critical, generally depending on a combined evaluation of qualities of services (Qos). This paper proposes a QoS-based selection of services. Initially we specify a QoS ontology and its vocabulary using the Web Services Modeling Ontology (WSMO) for annotating service descriptions with QoS data. We continue by defining quality attributes and their respective measurements along with a QoS selection model. Finally, we present a fair and dynamic selection mechanism, using an optimum normalization algorithm. 1
QoS-Aware Replanning of Composite Web Services
- In ICWS 2005 Proc
, 2005
"... Run-time service discovery and late-binding constitute some of the most challenging issues of service–oriented software engineering. For late-binding to be effective in the case of composite services, a QoS-aware composition mechanism is needed. This means determining the set of services that, once ..."
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Cited by 58 (5 self)
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Run-time service discovery and late-binding constitute some of the most challenging issues of service–oriented software engineering. For late-binding to be effective in the case of composite services, a QoS-aware composition mechanism is needed. This means determining the set of services that, once composed, not only will perform the required functionality, but also will best contribute to achieve the level of QoS promised in Service Level Agreements (SLAs). However, QoS-aware composition relies on estimated QoS values and workflow execution paths previously obtained using a monitoring mechanism. At run-time, the actual QoS values may deviate from the estimations, or the execution path may not be the one foreseen. These changes could increase the risk of breaking SLAs and obtaining a poor QoS. Such a risk could be avoided by replanning the service bindings of the workflow slice still to be executed. This paper proposes an approach to trigger and perform composite service replanning during execution. An evaluation has been performed simulating execution and replanning on a set of composite service workflows.
A Framework for QoS-Aware Binding and Re-Binding of Composite Web Services
"... QoS-aware dynamic binding of composite services provides the capability of binding each service invocation in a composition to a service chosen among a set of functionally equivalent ones to achieve a QoS goal, for example minimizing the response time while limiting the price under a maximum value. ..."
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Cited by 53 (2 self)
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QoS-aware dynamic binding of composite services provides the capability of binding each service invocation in a composition to a service chosen among a set of functionally equivalent ones to achieve a QoS goal, for example minimizing the response time while limiting the price under a maximum value. This paper proposes a QoS-aware binding approach based on Genetic Algorithms. The approach includes a feature for early run-time re-binding whenever the actual QoS deviates from initial estimates, or when a service is not available. The approach has been implemented in a framework and empirically assessed through two different service compositions.
End-to-End Support for QoSAware Service Selection, Invocation and Mediation in VRESCo. Retrieved November 10, 2009, from Vienna University of Technology: http://www.infosys.tuwien.ac.at/Staff/michlmayr/papers/TUV1841-2009-03.pdf (Technical Report
, 2009
"... Abstract—Service-Oriented Computing has recently received a lot of attention from both academia and industry. However, current service-oriented solutions are often not as dynamic and adaptable as intended because the publish-find-bind-execute cycle of the Service-Oriented Architecture triangle is no ..."
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Cited by 47 (23 self)
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Abstract—Service-Oriented Computing has recently received a lot of attention from both academia and industry. However, current service-oriented solutions are often not as dynamic and adaptable as intended because the publish-find-bind-execute cycle of the Service-Oriented Architecture triangle is not entirely realized. In this paper, we highlight some issues of current web service technologies, with a special emphasis on service metadata, Quality of Service, service querying, dynamic binding, and service mediation. Then, we present the Vienna Runtime Environment for Service-Oriented Computing (VRESCo) that addresses these issues. We give a detailed description of the different aspects by focusing on service querying and service mediation. Finally, we present a performance evaluation of the different components, together with an end-to-end evaluation to show the applicability and usefulness of our system. Index Terms—Web services publishing and discovery, metadata of services interfaces, advanced services invocation framework. Ç 1
Probabilistic QoS and Soft Contracts for Transaction-Based Web Services Orchestrations
- IEEE Trans. on Services Computing
, 2008
"... Abstract—Service level agreements (SLAs), or contracts, have an important role in Web services. These contracts define the obligations and rights between the provider of a Web service and its client, with respect to the function and the Quality of Service (QoS). For composite services like orchestra ..."
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Cited by 46 (17 self)
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Abstract—Service level agreements (SLAs), or contracts, have an important role in Web services. These contracts define the obligations and rights between the provider of a Web service and its client, with respect to the function and the Quality of Service (QoS). For composite services like orchestrations, such contracts are deduced by a process called QoS contract composition, based on contracts established between the orchestration and the called Web services. These contracts are typically stated in the form of hard guarantees (e.g., response time always less than 5 msec). Using hard bounds is not realistic, however, and more statistical approaches are needed. In this paper, we propose using soft probabilistic contracts instead, which consist of a probability distribution for the considered QoS parameter—in this paper, we focus on timing. We show how to compose such contracts to yield a global probabilistic contract for the orchestration. Our approach is implemented by the TOrQuE tool. Experiments on TOrQuE show that overly pessimistic contracts can be avoided and significant room for safe overbooking exists. An essential component of SLA management is then the continuous monitoring of the performance of called Web services to check for violations of the agreed SLA. We propose a statistical technique for runtime monitoring of soft contracts.
