Partial Selection: An Efficient Approach for QoS-Aware Web Service Composition

Background/Objectives: This article proposes a novel methodology based on rubrics and feature-based schemes for the appraisal and comparison of approaches to semantic Web services composition and discovery. Methods/Statistical analysis: In order to evaluate the Semantic Web services composition and discovery approaches we created a new framework called RFSWS. This framework is the combination of traditional feature-based evaluation schemes and newly developed analytic rubrics tables. Five recently introduced prominent Semantic Web services composition approaches were identified, explained, and then evaluated/compared using RFSWS. Findings: In this work we determined aspects of Semantic Web services composition and discovery processes that can be evaluated as performance criteria in rubric tables. This is a novel application of rubrics, which have traditionally been used for grading student performance by teachers. We created a novel framework called RFSWS consisting of rubric tables and a feature-based evaluation scheme for the evaluation and comparison of Semantic Web service discovery and composition approaches, and applied it in the evaluation of five recently introduced prominent Semantic Web services composition approaches. Considering the shortcomings of existing Semantic Web services composition approaches that were discovered through this evaluation, we proposed an idealized dynamic Semantic Web service discovery and composition method, a yardstick by which all future Semantic Web services composition approaches can be evaluated. Application/ Improvements: Our novel RFSWS framework can be applied in the comprehensive and systematic evaluation/comparison of Semantic Web services discovery and composition approaches.

E-Government services are increasingly being deployed using service-based architectures. Individual web services, developed from legacy and modern firmware, are composed to achieve e-service delivery. Current web service composition approaches range from practical languages aspiring to become standards (like BPEL, WS-CDL, OWL-S and WSMO) to theoretical models (like automata, Petri nets and process algebras). In this work, current approaches were studied and a comparison of their features and weaknesses was carried out. It was observed that current composition mechanisms are static and not agile enough to cater for functional change in business needs. This paper proposes a new web service composition and messaging mechanism for electronic government services in which composition of web services is done dynamically to provide for more agility in government e-services. The proposed composition mechanism works on a software architecture which enables application software integration. This architecture has been developed to deploy end-to-end e-services to G2B, G2C and G2G users starting from legacy government software applications. Using the proposed approach, integrating back-end e-Government applications to deliver end-to-end e-services can be agile, simpler and faster. The main contribution of this paper is the novel dynamic web service composition mechanism.

Integrating modified cuckoo algorithm and creditability evaluation for QoS-aware service composition

Composition of Web services is a cornerstone step in the development of interoperable systems. However, Web services still face data-heterogeneity challenges, although several attempts of using semantics. In addition, the context in which Web services evolve is still somehow ”ignored”, hampering their adaptability to changes in composition situations. In this paper, we argue how context permits to determine the semantics of interfaces that Web services expose to third parties. We show the need for a context- and semantic-based approach for Web services composition.

Web service composition (WSC) is the task of combining a chain of connected single services together to create a more complex and value-added composite service. Quality of service (QoS) has been mostly applied to represent nonfunctional properties of web services and differentiate those with the same functionality. Many research has been done on QoS-aware service composition, as it significantly affects the quality of a composite service. However, existing methods are restricted to predefined workflows, which can incur a couple of limitations, including the lack of guarantee for the optimality on overall QoS and for the completeness of finding a composite service solution. In this paper, instead of predefining a workflow model for service composition, we propose a novel planning-based approach that can automatically convert a QoS-aware composition task to a planning problem with temporal and numerical features. Furthermore, we use state-of-the-art planners, including an existing one and a self-developed one, to handle complex temporal planning problems with logical reasoning and numerical optimization. Our approach can find a composite service graph with the optimal overall QoS value while satisfying multiple global QoS constraints. We implement a prototype system and conduct extensive experiments on large web service repositories. The experimental results show that our proposed approach largely outperforms existing ones in terms of solution quality and is efficient enough for practical deployment.

As Web services become widespread, many complex applications require service composition to cope with high scalability and heterogeneity. Centralized Web service composition approaches are not sufficient as they always limit the scalability and stability of the systems. How to efficiently compose and adapt Web services under decentralized environments has become a critical issue, and important research question in Web service composition. In this paper, a stigmergic-based approach is proposed to model dynamic interactions among Web services, and handle some issues in service composition and adaptation. In the proposed approach, Web services and resources are considered as multiple agents. Stigmergic-based self-organization among agents are adopted to evolve and adapt Web service compositions. Experimental results indicate that by using this approach, service composition can be efficiently achieved, despite dealing with incomplete information and dynamic factors in decentralized environments.

Managing Service Level Agreement (SLA) for composite semantic web services is a very complex process, as it involves many complex tasks such as components discovery, provisioning, monitoring, recovery, and coordination. Indeed, managing all these tasks manually is a very cumbersome operation, nevertheless it is time consuming and prone to errors. To overcome such problems, automated SLA management for composite semantic web services is needed. This requires the SLA of the composite service to be described in a machine-understandable format such that it can be understood and processed by the automated SLA management tool. Currently, there is no SLA description language for composite semantic web services, but there exists an SLA description language for atomic web services, known as the Web Service Level Agreement (WSLA). Hence, in this paper, we aim to extend the WSLA language to describe composite semantic web services' SLAs, then we show how we can automatically generate the components' SLAs from the composite semantic web services' SLAs; adopting the CRECENT framework that we previously proposed for managing composite web services.

With the proliferation of Web services as a business solution to enterprise application integration, ranking and selecting the best Web services among the providers become an important factor in the success of the business solution. Quality of service (QoS) determines the quality and usability of a service including its price, performance, reliability, integrity, accessibility, availability, interoperability, and security. Given a set of QoS attributes from a variety of sources, it is a challenge to sort through all of them and be able to get the best services that meet QoS requirement. In this paper, we describe a novel method by which Web services can be ranked and selected automatically based on a number of observed QoS parameters and feedback responses learned from prior knowledge. This new approach treats the observed Web services QoS attributes and target Web services relationship, represented by a matrix, as a statistical problem. Using singular value decomposition (SVD) technique, and an user assisted weighting system, implicit higher order correlations among Web services and their associated QoS attributes are extracted and used to estimate the selection of recommended Web services.

Due to cloud computing and advanced web-based technologies, more and more service providers provide similar functionality web services with different QoS attribute values. The transactional behaviour of web services is described using transactional properties. Web services composition offers cost-effective construction of business applications. Finding a composite web service optimal in terms of QoS and transactional aspects is a multi-objective and challenging problem. Most of the existing optimization works proposed a single objective-based solution using weights assigned to various QoS attributes. They did not provide any information about weight assignment and used the weighted sum of QoS attributes as a fitness function. In this paper, we propose a modified grey wolf optimization approach for web services composition. Analytic Hierarchy Process (AHP) technique is used to assign weights to different QoS attributes. Fitness function is based on the Technique of Order Preference by Similarity to Ideal Solution (TOPSIS) technique. The proposed approach is compared with the genetic algorithm and Discrete Particle Swarm Optimization. Result analysis indicates the effectiveness of the proposed method.KeywordsWeb services compositionTOPSISAHPModified grey wolf optimization

Web services are provided as reusable software components in the services-oriented architecture. More complicated composite services can be combined from these components to satisfy the user requirements represented as a workflow with specified Quality of Service (QoS) limitations. The workflow consists of tasks where many services can be considered for each task. Searching for optimal services combination and optimizing the overall QoS limitations is a Non-deterministic Polynomial (NP)-hard problem. This work focuses on the Web Service Composition (WSC) problem and proposes a new service composition algorithm based on the micro-bats behavior while hunting the prey. The proposed algorithm determines the optimal combination of the web services to satisfy the complex user needs. It also addresses the Bat Algorithm (BA) shortcomings, such as the tradeoff among exploration and exploitation searching mechanisms, local optima, and convergence rate. The proposed enhancement includes a developed cooperative and adaptive population initialization mechanism. An elitist mechanism is utilized to address the BA convergence rate. The tradeoff between exploration and exploitation is handled through a neighborhood search mechanism. Several benchmark datasets are selected to evaluate the proposed bat algorithm’s performance. The simulation results are estimated using the average fitness value, the standard deviation of the fitness value, and an average of the execution time and compared with four bat-inspired algorithms. It is observed from the simulation results that introduced enhancement obtains significant results.

This paper presents a new approach for automatic Web service composition based on the formalism of Fluent Calculus using semantic Web service descriptions. In our approach, the Web service composition process is viewed as an AI planning problem in the Fluent Calculus formalism. To semantically describe Web services, we have used a Web service domain ontology which is then translated into a Fluent Calculus knowledge base, necessary for the composition planning phase. For verifying the composed services, the Label Transition System Analyzer (LTSA) formalism is used. The paper also presents an experimental prototype for the Fluent Calculus based Web service composition and demonstrates its effectiveness with the help of an application scenario from the social event planning domain.

Aiming at the hot and difficult issues in Web services and service composition, this paper analyzes and studies the selection of Web services and service composition from the functional and non functional attributes of Web services, and mainly makes the following work and innovation. First of all, the functional attributes of Web services are studied, Web services on various service provision platforms are collected, and Web services are classified. Secondly, aiming at the shortcomings of existing Web service QoS attribute evaluation models, an improved method is proposed, which introduces a comprehensive evaluation mechanism of variable weight vector. Based on the constant weight comprehensive evaluation method, the state variable weight vector is established to dynamically adjust the attribute weights of various service QoS indicators, so as to improve the accuracy and objectivity of the Web service QoS attribute evaluation. Finally, in view of the defects and deficiencies of traditional algorithms in the selection of Web service composition, the particle swarm optimization algorithm with linearly decreasing inertia weight and learning factor is introduced, which better balances the self cognition and social learning ability of particles, and improves the search speed and global search ability of particles. And a large number of experiments are carried out to compare it with the traditional algorithm, which verifies the effectiveness and superiority of the improved particle swarm optimization algorithm.

Web services run in a highly dynamic environment, as a result, the QoS of which will change relatively frequently. In order to make the composite service adapt to such dynamic property of Web services, we propose a self-healing approach for web service composition. Such an approach is an integration of backing up in selection and reselecting in execution. In order to make the composite service heal itself as quickly as possible and minimize the number of reselections, a way of performance prediction is proposed in this paper. On this basis, the self-healing approach is presented including framework, the triggering algorithm of the reselection and the reliability model of the service. Experiments show that the proposed solutions have better performance in supporting the self-healing Web service composition.

Web services facilitate reusability that allows cost-effective development of business applications using web services composition. Due to the proliferation of web services, different service providers are providing similar functionality web services. But these web services can have different values for QoS attributes and transactional properties. Thus, it is difficult to build a transactional and QoS optimal composite web service. Most of the existing works used the scalarization-based method for selecting optimal composite web service. In the scalarization-based method, the service user should have a priori knowledge of its preferences about the nonfunctional requirements of desired solutions. This paper proposes a Multiobjective Discrete Grey Wolf Optimization (MDGWO)-based approach for Transactional and QoS-driven Web Services Composition. The Pareto dominance concept is used to select optimal composite web service. Generational Distance (GD), Inverse Generational Distance (IGD), and Spread measures are used to evaluate the performance of the proposed approach. Experimental results indicate that the proposed approach performs well.

This paper presents a novel approach for semantic web service composition based on the formalism of fluent calculus. We show how the planning capabilities of the fluent calculus can be used to automatically generate an abstract composition model. For describing web service capabilities we have used an OWL-S ontology. Based on the OWL-S ontology semantics, we encode the web service description in the fluent calculus formalism and provide a planning strategy for service composition. For testing our composition method, we have implemented an experimental framework that automatically composes and executes web services.