Huipeng Guo

ANGEL: Optimal Configuration for High Available Service Composition

With the fast development of Internet and rapid acceptance of Web Service technology, more and more service resources have emerged. Service composition which integrates the functionalities of different services is a promising technique for developing applications across multiple organizations. However, in a distributed, dynamic and autonomous environment, such as a service composition-based system, the availability and reliability are big concerns in terms of nonfunctional properties. In this paper, we propose a novel service composition method, ANGEL, with the target of the improvement of system availability. We adopt redundant mechanism in ANGEL and propose a model to improve the property of the service availability. We model the multiple services selection problem based on redundant mechanism as a nonlinear mixed integer programming problem and therefore, we propose two heuristic algorithms to select multiple feasible services that have the same functions, but with better availability. In order to maintain the availability of composite services, we further introduce monitor and detection mechanisms. Through the comprehensive experiments, we find that our proposed techniques can indeed achieve better availability as expected.

An Adaptive Web Services Selection Method Based on the QoS Prediction Mechanism

In recent years, many QoS-based web service selection methods have been proposed. However, as QoS changes dynamically, the atomic services of a composite web service could be replaced with other ones that have better quality. The performance of a composite web service will be decreased if this replacement happens frequently in runtime. Predicting the change of QoS accurately in select phase can effectively reduce this web services “thrash”. In this paper, we propose a web service selection algorithm GFS (Goodness-Fit Selection algorithm) based on QoS prediction mechanism in dynamic environments. We use structural equation to model the QoS measurement of web services. By taking the advantage of the prediction mechanism of structural equation model, we can quantitatively predict the change of quality of service dynamically. Optimal web service is selected based on the predicted results. Simulation results show that in dynamic environments, GFS provides higher selection accuracy than previous selection methods.

QoS-aware Service Composition in Service Overlay Networks

As the amount of Web services over the Internet grows continuously, these services can be interconnected to form a service overlay network (SON). On the basis of SON, building value-added services by service composition is an effective method to satisfy the changeable functional and non-functional QoS (quality of service) requirements of customers. However, the previous research on QoS- aware service composition in SON mainly focuses on the context where services have simple interactions, and it can not support application scenarios with complex business collaboration in electronic business. In this paper, we propose the HOSSON (hierarchical service composition framework in SON) framework, which can be used to construct more general-purpose SON through describing the relations among services using business protocols. In HOSSON, business protocols instead of interactive messages are adopted to simplify the description of service composition requirements and a novel approach named protocol computing are proposed to implement service composition on demand. Furthermore, two algorithms, OSS and MCSS, are designed to support service selection for QoS-aware service composition. Finally, comprehensive simulations are conducted to evaluate the performance of algorithms.

PASS: An Approach to Personalized Automated Service Composition

With the rapid development of SOC (Service oriented computing), the automated service composition has become an important research direction. Through automated service composition, business processes need not to be constructed in advance, which helps to improve the flexibility of service composition. The current research on automated service composition is mainly based on AI techniques, and a common domain-oriented knowledge base is usually required to perform the heuristic planning. In practice, it is impossible for the knowledge base to characterize the personalized requirements of different users, so the AI-based methods can not apply to the user-centric application scenarios. In this paper, we propose PASS, a novel approach to personalized automated service composition. With PASS, both the hard-constraints represented by users initial state, and the soft-constraints represented by user preferences can be satisfied in the process of automated service composition. Furthermore, three algorithms are designed to implement preference-aware automated service composition. In these algorithms, the Pareto dominance principle and relaxation degree are used to select the most satisfied composite service for users. Finally, comprehensive simulations are conducted to evaluate the performance and effectiveness of the proposed algorithms.

AutoSyn: A new approach to automated synthesis of composite web services with correctness guarantee

How to compose existing web services automatically and to guarantee the correctness of the design (e.g. freeness of deadlock and unspecified reception, and temporal constraints) is an important and challenging problem in web services. Most existing approaches require a detailed specification of the desired behaviors of a composite service beforehand and then perform certain formal verification to guarantee the correctness of the design, which makes the composition process both complex and time-consuming. In this paper, we propose a novel approach, referred to as AutoSyn to compose web services, where the correctness is guaranteed in the synthesis process. For a given set of services, a composite service is automatically constructed based on L* algorithm, which guarantees that the composite service is the most general way of coordinating services so that the correctness is ensured. We show the soundness and completeness of our solution and give a set of optimization techniques for reducing the time consumption. We have implemented a prototype system of AutoSyn and evaluated the effectiveness and efficiency of AutoSyn through an experimental study.

GOS: A Global Optimal Selection Approach for QoS-Aware Web Services Composition

Services composition technology provides a promising way to create a new service in services-oriented architecture (SOA). However, some challenges are hindering the application of services composition. One of the greatest challenges for composite service developer is how to select a set of services to instantiate composite service with quality of service (QoS) assurance across different autonomous region (e.g. organization or business). To solve QoS-aware Web service composition problem, this paper proposes a global optimization selection (GOS) based on prediction mechanism for QoS values of local services. The GOS includes two parts. First, local service selection algorithm can be used to predict the change of service quality information. Second, GOS aims at enhancing the run-time performance of global selection by reducing to aggregation operation of QoS. The simulation results show that the GOS has lower execution cost than existing approaches.

Automated synthesis of composite services with correctness guarantee

In this paper, we propose a novel approach for composing existing web services to satisfy the correctness constraints to the design, including freeness of deadlock and unspecified reception, and temporal constraints in Computation Tree Logic formula. An automated synthesis algorithm based on learning algorithm is introduced, which guarantees that the composite service is the most general way of coordinating services so that the correctness is ensured. We have implemented a prototype system evaluating the effectiveness and efficiency of our synthesis approach through an experimental study.

GOS: a global optimal selection strategies for QoS-aware web services composition

Services composition technology provides a promising way to create new services in services-oriented architecture. However, some challenges are hindering the application of services composition. One of the major challenges encountered by composite services developer is how to effectively select a set of services across different autonomous regions (e.g., organization or business) to instantiate a composite service which can satisfy user’s QoS constraints. To solve QoS-aware Web service composition problem, this paper proposes a global optimization selection (GOS) approach based on prediction mechanism for QoS values of local services. The GOS includes two parts. First, the local preprocessing service selection algorithm can be used to increase composite services performance in run-time by predicting the change of service quality parameters. Second, GOS aims at enhancing the run-time performance of global selection by reducing QoS aggregation operations. The simulation results show that the GOS has excellent selection and lower execution cost than existing approaches.

PAAS: A Protocol-based Approach to Adaptive Service Composition

For the development of network applications across multiple organizations, Service composition has been widely accepted as a promising technique. However, the atomic services are generally dynamic and distributed over the Internet, how to guarantee the adaptiablity capability in such open environment has become an important issue. In this paper, we address this problem by proposing a novel approach—PAAS (Protocol-based Approach for Adaptive Service Composition). We firstly design a protocol based system architecture supporting adaptive service composition. Then, we propose adaptive mechanisms based on the service and protocol optimization. Furthermore, we design adaptive service composition algorithm base on policies and protocols to deal with the variety of service resources and requirements. Finally we implement the PAAS approach and evaluate the proposed mechanism.

PASCAL: A Protocol-Based Approach for Service Composition and Dependable Optimization

Service composition is a promising technique for developing applications especially for those across multiple organizations. The dependability of composite services, however, is difficult to be guaranteed due to the distributed, dynamic and autonomous characteristics of service domains. In this paper, we address this problem by proposing a novel approach—PASCAL (Protocol-based Approach for Web Service Composition And Dependable Optimization). We initially propose a protocol based service composition system architecture supporting online monitoring of services interaction and dynamic replacing of service. Then, we design the dependable optimization mechanism based on the service and dependencies monitoring. Furthermore, we design an algorithm to adjust the configuration adaptively base on policies and protocols to keep the composite service dependable while service failure appears. Finally we implement the PASCAL approach based on XService suit and evaluate the proposed mechanism through comprehensive experiments and achieve improved results.