Multi-user web service selection based on multi-QoS prediction

With the development of Service-Oriented technologies, the amount of Web services grows rapidly. QoS-Aware Web service recommendation can help service users to design more efficient service-oriented systems. However, existing methods assume the QoS information for service users are all known and accurate, but in real case, there are always many missing QoS values in history records, which increase the difficulty of the missing QoS value prediction. By considering the user-service-time three dimension context information, we study a Temporal QoS-Aware Web Service Recommendation Framework which aims to recommend best candidates to service user's requirements and meanwhile improve the QoS prediction accuracy. We propose to envision such QoS value data as a tensor which is known as multi-way array, and formalize this problem as a tensor factorization model and propose a Tucker decomposition (TD)algorithm which is able to deal with the triadic relations of user-service-time model. However, one major challenge is that how to deal with the dynamic incoming service QoS value data streams. Thus, we introduce the incremental tensor factorization (ITF)method which is (a) scalable, (b) space efficient (it does not need to store the past data). Extensive experiments are conductedbasedc on our real-world QoS dataset collected on Planet-Lab, comprised of service invocation response-time values from 408 users on 5,473 Web services at 240 time periods. Comprehensive empirical studies demonstrate that our approach is faster and more accuracy than other approaches.

Web service recommendation is of great importance when users face a large number of functionally-equivalent candidate services. To recommend Web services that best fit a user's need, QoS values which characterize the non-functional properties of those candidate services are in demand. But in reality, the QoS information of Web service is not easy to obtain, because only limited historical invocation records exist. To tackle this challenge, in recent literature, a number of QoS prediction methods are proposed, but they still demonstrate disadvantages on prediction accuracy. In this paper, we design a location-based hierarchical matrix factorization (HMF) method to perform personalized QoS prediction, whereby effective service recommendation can be made. We cluster users and services into several user-service groups based on their location information, each of which contains a small set of users and services. To better characterize the QoS data, our HMF model is trained in a hierarchical way by using the global QoS matrix as well as several location-based local QoS matrices generated from user-service clusters. Then the missing QoS values can be predicted by compactly combining the results from local matrix factorization and global matrix factorization. Comprehensive experiments are conducted on a real-world Web service QoS dataset with 1,974,675 real Web service invocation records. The experimental results show that our HMF method achieves higher prediction accuracy than the state-of-the-art methods.

THE Internet, along with its related technologies, has created an interconnected world in which information flows easily and tasks are processed collaboratively. To make service-oriented applications more robust, Web services must be examined from a transactional perspective. By transactional, we mean first defining the actions that guide the execution of Web services when failures arise and then the states that permit claiming the success of this execution following the handling of these failures. A variety of transactional models are reported in the database community. Some of these models can be leveraged and enhanced in response to Web services characteristics while others are not suitable for Web services due to the dynamic nature of Web services, the long-running execution scenarios that Web services take part in, and the successful execution of Web services despite other peers’ failure. Today’s service-oriented applications require advanced transactional models that guarantee integrity and continuity of business processes despite the dynamic nature of the features of the environments hosting the execution of these applications. This special section sheds light on the latest advances in the fields of Web services and transactional models in order to better address advanced research on and experience with transactional Web services. Four papers out of 19 submissions were selected for inclusion in this special section. Each submission was subject to a double-review process by at least three peer reviewers. In the first paper, entitled “Event-Based Design and Runtime Verification of Composite Service Transactional Behavior,” Gaaloul et al. propose an event-driven approach to validate the transactional behavior of Web services taking part in compositions. A composition life cycle consists of four phases, namely, design, execution, monitoring, and reengineering. The verification of this behavior throughout this life cycle is done either at design time to validate recovery mechanisms’ consistency or after runtime to detect execution deviations and repair design errors, and, therefore, formally ensure the execution reliability of Web services. In addition, this verification is based on the Event Calculus formalism, which offers a sound definition for this reliability. In the second paper, entitled “FACTS: A Framework for Fault-Tolerant Composition of Transactional Web Services,” Liu et al. note that delivering reliable compositions over unreliable Web services is challenging. To address this challenge, Liu et al. identify a set of high-level exception handling strategies and a new taxonomy of transactional Web services to devise a fault-tolerant mechanism that combines exception handling and transaction techniques. In addition, Liu et al. devise two modules, known as specification and verification, to assist service designers in constructing fault handling logic conveniently and correctly. This logic is automatically injected into WS-BPEL. In the third paper, entitled “Rule-Based Coordination of Distributed Web Service Transactions,” von Riegen et al. study the distributed transactional activity control problem in the context of service choreographies. In such a context, many participants are allowed to work together to achieve a global, common goal, and the initiator of a process is not always the one who is able to commit or cancel a transaction. Von Riegen et al. introduce a framework that allows autonomous coordination of dynamic processes. This framework extends WSBusinessActivity to strengthen the role of the coordinator. Predicate rules are developed to let participants cancel or complete a process and help the coordinators decide on the completion processes and the confirmation or cancellation of the participants’ works. In the fourth paper, entitled “TQoS: Transactional and QoS-Aware Selection Algorithm for Automatic Web Service Composition,” El Haddad et al. focus on the issues of selecting and composing Web services. A design-time selection algorithm is proposed in which transactional and QoS requirements are both integrated into the selection process. This algorithm is based on the notion of risk that indicates if execution outcomes can either be compensated for or not. Two risk levels of execution in a transactional system are considered: Risk 0, meaning that if the execution is successful, the obtained outcomes can be compensated for by the user, and Risk 1, meaning that the system does not guarantee successful execution, but if it achieves it, the outcomes cannot be compensated for by the user. We hope this special section inspires researchers to develop new transactional models that would guarantee service-oriented applications integrity and continuity. 30 IEEE TRANSACTIONS ON SERVICES COMPUTING, VOL. 3, NO. 1, JANUARY-MARCH 2010

Virtual enterprise is a temporary network of independent companies or enterprises that can quickly bring together to fulfill a value-added task. With the development of Web service technologies, the enterprise business systems can be encapsulated as Web services. Establishing a virtual enterprise is actually a process of Web services composition. As more and more Web services are available, many Web services with different quality of service (QoS) can be found for tasks of the composite Web service. Thus, a significant research problem in Web service composition is how to select the correct Web services for tasks such that the composite Web service gives the best overall quality. In this paper, we propose an approach to achieve Web services selection efficiently with excellent comprehensive quality. Firstly, a comprehensive evaluation model based on generic QoS (GQoS) and domain QoS (DQoS) of composite Web service is established. Secondly, a novel optimization algorithm named culture max–min ant system (C-MMAS) is constructed to solve the problem of Web service selection based on DGQoS. Simulations show that when used in Web service selection, C-MMAS is better than ant colony optimization algorithm and MMAS in efficiency.

SUMMARY The availability of more and more Web services provides great varieties for users to design service processes. However, there are situations that services or service processes cannot meet users’ requirements in functional QoS dimensions (e.g., translation quality in a machine translation service). In those cases, composing Web services and human tasks is expected to be a possible alternative solution. However, analysis of such practical efforts were rarely reported in previous researches, most of which focus on the technology of embedding human tasks in software environments. Therefore, this study aims at analyzing the effects of composing Web services and human activities using a case study in the domain of language service with large scale experiments. From the experiments and analysis, we find out that (1) service implementation variety can be greatly increased by composing Web services and human activities for satisfying users’ QoS requirements; (2) functional QoS of a Web service can be significantly improved by inducing human activities with limited cost and execution time provided certain quality of human activities; and (3) multiple QoS attributes of a composite service are affected in different ways with different quality of human activities.

Service Oriented Architecture (SOA) introduced the web services as distributed computing components that can be independently deployed and invoked by other services or software to execute composite services that represent an end-to-end business process. An important problem in the SOA is the web service selection and composition problem which involves selecting the right web services mix to construct the best service composition that achieves the consumers Service Level Agreement (SLA) requirements. In this chapter we propose different methods to solve the problem of the business processes execution engine web service selection and services composition construction in the Service Oriented Architecture (SOA).  The chapter provides different mechanisms to improve the web services selection and composition using dynamic techniques. The main goal is to satisfy the services' requirements expressed as the SLA and to enhance the services selection and composition by increasing the availability and decreasing the response time of the service compositions.

Service-oriented computing is gaining momentum. Now-a-days web services are geared up to occupy center stage as part of this adoption. In this new paradigm, existing business logic would be wrapped as web services to be accessible on the web. As the number of web services is expected to significantly increase, this would have the effect of introducing competition among web services that offer similar functionalities. Selection of best service based on their expected quality such as price, response time has more importance. Sound framework is essential to organize web services. The identified key challenges are publishing of service QoS information, the matching of QoS requirements. A model for web services discovery is proposed as a solution. The discovery agent finds services that best meet a consumer's QoS and rating requirements that are specified in a discovery request.

Proliferation of web services opens an unleashed opportunity to the service providers compete themselves to satisfy a request. Since numerous functionally similar web services are readily available, identifying pertinent web service to the client's requirement is a challenge. Furthermore, recommending the pertinent web service and not missing the relevant web service are the two complex issues to be addressed in service discovery process. Since the keyword search doesn't bear the underlying semantics and unable to articulate the search query accurately, operation based search has been introduced. The discovery process is matured, if the search must be incorporated with client's QoS requirements. To alleviate the aforementioned difficulties, QoS driven web service discovery approach has been introduced. The gist of the approach is to assist the user to search the pertinent web service based on functional and non functional evaluation. The web services metadata are extracted from the WSDL file and it will be stored in a service pool. The functional and nonfunctional evaluation can be performed by the proposed algorithm, and the aggregated value will be stored in a service pool. The services which are matched with the user query will be provided to the client.

Web services over the Web had became more and more, and makes the requester to use tools to search for suitable Web services available throughout the globe. Web services QoS management frameworks had proposed such as QoS specification, Qos comprehensive quality, QoS monitoring of Web services and so on. In this paper, a model is investigated that not only based on QoS specification, Qos comprehensive quality, but also load Balancing. The QoS broker, based architecture for dynamic Web service selection which facilitates the requester to specify his/her QoS requirements along with functional requirements by considering the service load balancing, is presented here. The experiments have been conducted using the above model, have shown that better Web service is obtained as the requester’s functional and quality requirements.

Now a days, Web services are becoming the primary source for constructing software system over Internet. The quality of whole system greatly dependents on the QoS of single web service, so QoS information is an important indicator for service selection. But in reality, QoSs of some Web Services may be unavailable for users. How to predicate the missing QoS value of Web service through fully using the existing information is a difficult problem. This study first proposes a novel method for clustering similar web services using semantic approach in order to overcome the limitations of pattern-matching approach and finally proposes a cluster based approach using Slope One Collaborative filtering method to predict the QoS values for similar web services for similar users. Proposed approaches are applied on a dataset consisting of WSDL files and QoS values for various QoS parameters which are collected from the Internet and the proposed approaches shows better qualities with respect to clusters formed and the QoS values predicted.

The rapidly growing number and complexity of web services available on the Web raise a novel and challenging problem: utilizing semantics to organize web services for more effective services searching. Traditional UDDI is insufficient in this context, since the underlying semantics of web services are not exploited enough. Also, the user requirements are not described explicitly and consistently. Considering this situation, we construct a SAM-based service model for web services management, SAM-WS, and propose an approach for users to explicitly describe their QoS requirements using QoS ontology. Experimental results show the effectiveness by comparison of our approach and traditional keyword search.

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 real-time 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-to-optimal results.

The rapidly growing number and complexity of web services available on the Web raise a novel and challenging problem: utilizing semantics to organize web services for more effective services searching. Traditional UDDI is insufficient in this context, since the underlying semantics of web services are not exploited enough. Also, the user requirements are not described explicitly and consistently. Considering this situation, we construct a SAM-based service model for web services management, SAM-WS, and propose an approach for users to explicitly describe their QoS requirements using QoS ontology. Experimental results show the effectiveness by comparison of our approach and traditional keyword search.

Service-Oriented Communication (SOC) is a new development in the industry to enable communication through web services and SOA. SOC is to make communication as service and provide a service-oriented architecture to integrate communication in business applications. Recent advances of web service and SOA have made it possible for a full web service and SOA based communication paradigm over IP. This paper is an overview of the recent development in this area with a focus on key technologies that can be applied to web service enablement of communication. In particular, we discuss the generic web service based application session management based on WS-Session, the two-way full duplex web service interaction framework, and the development of Web Service Initiation Protocol (WIP). WIP is a full web service and SOA based communication protocol for multimedia and voice communication over IP. The generic web service approach of WIP overcomes many limitations which would be otherwise difficult to achieve in non-web service based communication methods used today. In addition, we discuss the service composition and orchestration framework based on WS-BPEL, and illustrate the application of this approach through some real use cases.

A Wireless Sensor Network (WSN) is a collection of sensor nodes, spatially deployed in an ad hoc fashion, which performs distributed sensing tasks in a collaborative manner, without relying on any underlying infrastructure support. WSNs have usually been treated as passive networks, where sensors measure some physical phenomena periodically, or detect some events, and then send the data thus generated to the sink. Another kind of application is emerging, both in the context of a stand-alone WSN and of distributed WSNs, for the Internet of Things (IoT) where, instead of serving only as passive, information gathering mechanisms, sensors can actively process and respond to user queries to report the sensed data on demand. Irrespective of the query types, query processing tasks in WSNs pose several technical challenges, such as (i) selecting the appropriate sensors, within a stand- alone WSN or the appropriate WSNs among the distributed WSNs in the IoT, which satisfy the query specifications; (ii) providing the query response within the user-specified delay bound; (iii) ensuring higher query response accuracy; and (iv) determining the query execution plan dynamically to satisfy the QoS requirements on either delay or accuracy, or a combined specification of both delay and accuracy. This thesis aims to address these issues by developing a hierarchical data model for representing the sensor data of a stand-alone WSN at sensor, fusion node and sink levels. In the case of an aggregate query, the model can be used to select the appropriate sensors which satisfy the query specifications. In the case of an approximate query, the model can provide the approximate query response directly from the model. In both instances, the data model enables retrieving the query response with higher accuracy and less data transmission. To execute a query in delay sensitive applications, a delay aware spanning tree is designed, which provides a routing path for query dissemination to the target sensors as well as collecting a response from them. The tree is constructed based on the query load of the sensors so that the sensors with a higher query load can be reached quickly thus causing less delay in retrieving the query response. Moreover, to support the query execution according to the QoS requirements on delay and accuracy, the hierarchical data model is applied on the delay aware spanning tree to generate a QoS aware sensor model. The model organises sensor data hierarchically, with different levels of accuracy, on different hop distances of the tree. It creates the provision to collect the query response from any hop distance of the tree to satisfy the query-specified delay and accuracy bound. Then, the formulations are extended for the distributed WSNs in the context of the IoT. In doing so, a distributed WSNs information model is maintained in the web server which gathers the data models and the spatial properties of the WSNs from their associated QoS aware sensor models. The information model exploits the overlapping information among the participating WSNs and facilitates selecting the appropriate WSNs it is necessary to visit according to the query specifications. Moreover, based on the QoS requirements of the query, the information model determines the cost effective query execution plan, with the help of the QoS aware sensor models of the respective WSNs. Extensive analytical and simulation analyses confirm the efficacy of the proposed new strategies compared with notable work in this area.