Web Service Composition Approach Research Articles

Multi‐objective memetic approach for the optimal web services composition

AbstractService composition is the process of combining a set of elementary or atomic services. The aim is to produce a new composite service to satisfy the user's request that cannot be satisfied by the atomic services. Combining multiple services is a complex problem that has been the subject of several research studies. The meta‐heuristic approaches are good techniques that have been used to solve several complex problems in various domains. These techniques are able to discover promising search regions and locate good quality solutions in reasonable time without exploring the whole solution space. In this paper, we deal with the problem of optimal web service composition by using meta‐heuristic approaches. Given a set of services and a set of tasks to be completed, the problem is to find the best set of services composition to complete all tasks where each service must be assigned to a given task. This problem can be modelled as a combinatorial optimization problem with a set of objective functions that need to be optimized. We search for a composite service that allows us to execute the considered tasks and offers the best quality of services (QoS). More precisely, we search for an execution plan that indicates for each task the assigned service. First, we propose a multi‐objective local search based meta‐heuristic (MO‐LS) and a multi‐objective genetic algorithm (MO‐GA) to handle our problem. Then we propose a multi‐objective memetic algorithm (MO‐MA) that combines the two methods LS and GA. The role of GA is to detect promising regions to be explored. The role of LS is to exploit efficiently the potential regions created by GA. Four objective functions are used to compute the Pareto optimal set of solutions. The main objective is to minimize cost and time and to maximize availability and reputation and produce a good composite service. The three proposed approaches namely MO‐LS, MO‐GA, and MO‐MA are evaluated on some datasets generated randomly and on the well‐known QWS dataset to select the best fit services in terms of maximum or minimum aggregated end‐to‐end QoS parameters. The numerical results are encouraging and demonstrate the effectiveness of the proposed MO‐MA for the web service composition.

Coordinate System-Based Trust-Aware Web Services Composition in Edge and Cloud Environment

Abstract In the next few years, the number of devices connected to the web will increase dramatically. This has encouraged the development of complexes and intelligent service-based applications using new paradigms and technologies such as edge computing and cloud computing. These applications are mainly built by the interaction between heterogonous web services. Answering end-users’ queries demands that these services collect, integrate and communicate sensitive data, which makes the vulnerability of data a serious issue. Thereby, this issue is a critical problem in the automatic services composition while users are frequently unquieted about the security and control of their sensitive data. To address this problem, our main idea is that avoiding disclosure of sensitive information can be ensured by selecting services where their mutual trust is high while preserving a good quality of service (QoS) as possible. A new Heuristic Trust-aware Web Services Composition Approach (CWS_SMA) is proposed. CWS_SMA aims to: (i) compute an optimal trust and QoS-aware web services composition based on the mathematical coordinate system, (ii) improve the composition response time based on a set of cooperative intelligent agents. Eventually, the simulations results show the effectiveness of the proposed solution.

A Multiobjective Discrete Grey Wolf Optimization Approach for Transactional and QoS-driven Web Services Composition

ABSTRACT 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.

A Survey of Evolutionary Computation for Web Service Composition: A Technical Perspective

Service oriented computing has emerged as a popular software development paradigm. In the era of Cloud computing, Big data, the Internet of Things (IoT) and Smart Cities, Web service composition has been extensively researched. Web service composition aims to find the best way of combining services, which accomplish simple tasks, into a more sophisticated composite application. Evolutionary computation lends itself to tackling the problem of Web service composition, since it allows for the optimisation of the overall Quality of Service attributes of the composite solution. In order to gain a better understanding of the different evolutionary computation-based approaches applied to this problem, a number of literature surveys have been written in this area. However, these surveys do not focus on the technical aspects of using evolutionary computation to this end, instead focusing on the general application of methods. Thus, the focus of this survey is on analysing existing works from a technical perspective, paying particular attention to the following key decisions when choosing an evolutionary computation-based approach for Web service composition: a) the representation of candidates, b) the fitness evaluation strategy, c) the handling of correctness constraints, d) the choice of evolutionary algorithms and operators. Based on these analyses, current trends, limitations, and future research paths are identified.

Automatic Dynamic Web Service Composition Using AND/OR Directed Graphs

In this article, the authors propose a dynamic web service composition approach based on representing the semantic relationship between web services using a weighted directed AND/OR graph. The nodes in this graph represent available services while the arcs represent the semantic input/output dependencies among them. The novelty of this work consists of constructing the graph and computing offline the shortest paths between each pair of its nodes to disconnect this tedious task from the composition query process. A set of dynamic optimization techniques has been included to reduce the size of the graph and thus improve the scalability and performance of this approach. In addition to the sequence and fork relations between services, this solution also supports the parallel relation. Furthermore, a recovery mechanism is integrated to ensure the continuity of the execution of the composition.

A Web Service Composition Approach Based on Planning Graph and Propositional Logic

To improve the computational efficiency of web service automatic composition, this article proposes a novel approach based on a planning graph and propositional logic. This approach has a forward searching stage and a backward combination stage: the former stage searches services in a service storage and performs the composition in a hierarchical architecture based on a planning graph, while the latter stage combines them via propositional logic operations. This method can obtain all composite services that contain no redundant services, and the computational complexity can be significantly reduced. Experiments are done to illustrate the effectiveness of the approach.

The dynamic reconfiguration approach for fault-tolerance web service composition based on multi-level VCSOP

The dynamism of web service on the internet brings new needs to build autonomous services. In practical environments, Web services could occur many incidents with unacceptable information and generate a large number of undesirable solutions. Thus, it becomes an additionally urgent challenge on how to adjust service-based applications to meet highly dynamic environments and fast-changing business requirements. A self-reconfigurable application becomes a necessity to produce an adequate web service process. To cope with this hindrance, the present paper proposes a sensor and repair-based algorithm to achieve reliability at the component level before a system crash occurs. We adopt a new sensor method based on project management rules to detect the faulty region on a workflow. After that, we applied the repair algorithm: such as a single service (SSR) and multiple service reconfiguration (MSR) that systematically search to find a new nearby solution. In MSR algorithm we referred to a new multi-level VCSOP with Harmony Search (HS) metaheuristic to quickly recover the faulty region without system crash. The results show that our proposed method could recover the original instance of the faulty region without user integration and in a very acceptable time regarding the recomposing process.

LP-WSC: a linear programming approach for web service composition in geographically distributed cloud environments

In recent years, cloud computing has emerged as the most popular technologies for accessing and delivering enterprise applications as the services to the end users over the Internet. Since different enterprises may offer web services with various capabilities, these web services can be combined with other to provide the complete functionality of a large software application to meet the users’ requests. Therefore, the service composition as an NP-hard optimization problem to combine the distributed and heterogeneous web services is introduced as a challenging issue. In this work, we propose a linear programming approach to web service composition problem which is called ‘LP-WSC’ to select the most efficient service per request in a geographically distributed cloud environment for improving the quality-of-service criteria. Finally, we evaluate the effectiveness of our approach under three scenarios with varying the number of atomic services per set. The experimental results indicate that the proposed approach significantly reduces the cost of selection and composition of the services and also increases the availability of services and the reliability of the servers compared with the other approaches.

Reusing process fragments for fast service composition: a clustering-based approach

ABSTRACTWith the proliferation of Web services over the Internet and due to the increasing complexity of users’ needs, Web service composition has emerged as a powerful method of software reuse, allowing to deliver complete business processes as a set of interacting services. To guarantee a rapid and secure service composition, fragments of available business processes at different granularities may be considered as a composition unit and recombined to deliver effective compositions. Despite the benefits of this method, most of the existing works do not take into consideration the reuse of service process fragments (SPF). Reusing SPFs allows, not only to minimize the composition time, but also to improve the reliability of the composition process. In this paper, we propose a Web service composition approach that aims to combine service process fragments rather that atomic services. We adopt a powerful mathematical model called Formal Concept Analysis (FCA) to define the relationships between services and fragments. Moreover, we exploit the regrouping capabilities of FCA by proposing algorithms for the extraction of candidate fragments’ combinations. A scoring function is also defined to determine the quality level of each SPF and its ability to participate in a composition. The experimental studies proved the effectiveness of our FCA-based approach compared to existing state-of-the-art solutions.

A quality-controlled logic-based clustering approach for web service composition and verification

PurposeService-oriented architecture is an emerging software architecture, in which web service (WS) plays a crucial role. In this architecture, the task of WS composition and verification is required when handling complex requirement of services from users. When the number of WS becomes very huge in practice, the complexity of the composition and verification is also correspondingly high. In this paper, the authors aim to propose a logic-based clustering approach to solve this problem by separating the original repository of WS into clusters. Moreover, they also propose a so-called quality-controlled clustering approach to ensure the quality of generated clusters in a reasonable execution time.Design/methodology/approachThe approach represents WSs as logical formulas on which the authors conduct the clustering task. They also combine two most popular clustering approaches of hierarchical agglomerative clustering (HAC) and k-means to ensure the quality of generated clusters.FindingsThis logic-based clustering approach really helps to increase the performance of the WS composition and verification significantly. Furthermore, the logic-based approach helps us to maintain the soundness and completeness of the composition solution. Eventually, the quality-controlled strategy can ensure the quality of generated clusters in low complexity time.Research limitations/implicationsThe work discussed in this paper is just implemented as a research tool known as WSCOVER. More work is needed to make it a practical and usable system for real life applications.Originality/valueIn this paper, the authors propose a logic-based paradigm to represent and cluster WSs. Moreover, they also propose an approach of quality-controlled clustering which combines and takes advantages of two most popular clustering approaches of HAC and k-means.

A clustering network-based approach to service composition in cloud manufacturing

Cloud manufacturing (CMfg) is a new business paradigm that aims to provide manufacturing resources as services over the Internet in a convenient pay-as-you-go mode. Service composition is a critical means for achieving value adding and synergy of resources in CMfg. There are a vast number of services in a CMfg platform, which makes traditional service composition methods incapable and low efficiency in solving the problem of service composition. Most of existing research on CMfg was devoted to the optimal selection of services under a specific composition flow and a group of given candidate pools. Hence, there is a need to explore effective approaches to obtaining service composition flow and candidate sets. The network-based web service composition approach has recently drawn much attention and has been proved effective in coping with the challenge of large-scale services. Inspired by this, a novel approach called service clustering network-based service composition is proposed in this paper. In this method, services are first clustered into abstract services, and then a clustering network of the abstract services is established. In this way, service composition paths and corresponding candidate sets for fulfilling manufacturing tasks can be quickly obtained without requiring task decomposition, which decreases the difficulty and improves efficiency of service composition. Effectiveness and efficiency of the approach are verified through simulation experiments.

A bitwise-based indexing and heuristic-driven on-the-fly approach for Web service composition and verification

During the last decade, software engineering community has witnessed the emerging of SOA architecture, where Web services play a crucial role. It prompts the concept of Web Service Composition (WSC). Even though interesting, this issue posed some remarkable challenges, one of which is constraint handling. To be more precise, one needs to ensure that the composite Web service fulfills, at the same time, many constraints, including functional constraints, Quality of Service (QoS), and the execution order of the component services, or temporal relations. Those constraints are of different natures, thus finding an efficient verification on all kinds of constraints during the composition process is by no means a trivial task. Backed by a solid foundation of temporal logic, model checking (MC) is a suitable approach to handle this issue. However, MC-based approach suffers from the infamous problem of state-space explosion, making it limited when applied to real-life situations. The work in this paper addresses the problem by proposing various approaches for handling the state-space exploration, including (i) an introduction of an LTS-based model known as LTS4WS, which can avoid generating full schema of Web service composition and allow on-the-fly verification on the state space; (ii) heuristics strategies to find the best potential composition, and (iii) a bitwise-based indexing mechanism for fast location of suitable Web services. All of those approaches are unified in a single tool, known as WSCOVER. As a result, a significant improvement of performance has been made, especially as compared with the other existing works in the same field.

A Novel Rubric and Feature-based Appraisaland Comparison Framework for the Evaluationof Semantic Web Services Composition Approaches

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.

Two-stage approach for reliable dynamic Web service composition

Web service composition is a key technology for creating value-added services by integrating available services. With the rapid development of Service Computing, Cloud Computing, Big Data, and the Internet of Things, mass services with the same functionalities and different quality of service (QoS) values are available on the Internet. Moreover, due to the uncertainties of services’ application environment, a service’s QoS is highly dynamic; these two factors cause reliable dynamic Web service composition to be a challenge. To address this issue, this paper proposes a two-stage approach for reliable dynamic Web service composition. In the first stage, the top K Web service composition schemes based on each service’s historical QoS values are selected with the proposed algorithm named Culture Genetic Algorithm (CGA). Then, component services in the top K schemes are filtered out and employed as the candidate services for dynamic service composition. This operation can greatly reduce the number of available services and filter out better candidate services for dynamic service composition. Next, the global QoS constraints are decomposed into local QoS constraints with the CGA algorithm, and the global optimal problem of service composition is transformed into a local optimal service selection problem; this conversion increases the flexibility of dynamic service composition and provides a chance to predict QoS values of services before service selection. In the second stage, before selecting the best service for each task during the running of the service composition workflow, QoS values of each candidate service are predicted based on the improved case-based reasoning, and the best service is selected according to the predicted QoS values. Through QoS prediction, the reliability of the composite Web service can be greatly enhanced. Finally, experimental results show that the proposed method is feasible and effective.

An interval-based fuzzy ranking approach for QoS uncertainty-aware service composition

Web services are a major technique for building loosely coupled distributed systems. QoS-aware service composition concerns the selection of candidate services while maximizing the overall Quality of Service (QoS). However, these approaches fail to take the uncertainty of QoS into account. The resultant QoS of composite service observed by users is therefore unstable and subject to risks of failing composition by end users. In this paper, we propose a QoS Uncertainty-aware Web Service Composition approach based on a novel QoS interval model. It performs evaluation under a trade-off between profit and stability of QoS in a fuzzy way, and selects out composite service among the numerous solutions with an overall more stable QoS. A Multi-criteria Decision Analysis (MCDA) method and improved Genetic Algorithm is introduced in this paper. Based on real-world dataset QWS, simulations validate the correctness of the interval model and demonstrate the performance of composite framework. A comparative study with traditional tentative model is also discussed briefly.

AOMD approach for context-adaptable and conflict-free Web services composition

BPEL or Business Process Execution Language is so far the most important standard language for effective composition of Web services. However, like most available process orchestration engines, BPEL does not provide automated support for reacting according to many changes that are likely to arise in any Web services composition, like downtime services, modifications in the business logic or even new policies to govern the composition. Also low-level specification of these new changes, which would be integrated at runtime in the BPEL process, will be far from being used conveniently. Moreover, the complexity of interaction in composite Web services and the diversity of rules and policies can lead to critical behavioral conflicts. We propose in this paper AOMD, a novel aspect-oriented and model driven approach that defines new grammar to address both adaptability and behavioral conflicts problems, and offers extension for WS-BPEL meta-model for high level specification of aspects. Further, we formally verify our proposition and we present real life case study, examples and experimental results that demonstrate the feasibility and effectiveness of our work.

A linear logic approach to the composition of RESTful web services

RESTful web services, which are declarative, lightweight and easy to access, are already widely used for exposing services on the internet and have attracted increasing interest from industry. The rising number of services being implemented and made available on the web is creating a demand for modelling techniques that can abstract REST design from the implementation in order to better specify, analyse and implement large-scale RESTful web systems. It can also help by providing suitable RESTful web service composition methods which can reduce costs by efficiently re-using the large number of services that are already available and by exploiting existing services for complex business purposes. This paper introduces a formal model of RESTful web services in linear logic and proposes a formal method approach for RESTful web service composition based on planning using linear logic via theorem proving. This is a two-stage planning method that finds resources for the composition at both the abstract resource and the service operation levels. It greatly improves the searching efficiency and guarantees the correctness and completeness of the service composition process. The paper demonstrates a further validation of the planning method through its implementation in the interactive Coq logic proof assistant.

Formal specification of flexible web service composition

Web services give a standard way for interface definition, transport mechanism, description, discovery and integration of services. Although the heterogeneity among applications is reduced, mismatches may occur at different levels structural, behavioural and non-functional during web services composition process. These mismatches require adaptation to ensure the correct working between web services. In this paper, we propose an approach for dynamic web service composition and adaptation. We specify formally the flexible web service composition FWSC using a rewriting logic-based language namely Maude. We show how to adapt the interfaces of existing web services without having to operate on the source manually. As a result, existing web services may be easily reused in a broader range of applications, and services libraries do not need to store many variants of a component that differ only in how the interfaces are used.

A genetic-based approach to web service composition in geo-distributed cloud environment

Independent fine-grain web services can be integrated to a value-added coarse-grain service through service composition technologies in Service Oriented Architecture. With the advent of cloud computing, more and more web services in cloud may provide the same function but differ in performance. In addition, the development of cloud computing presents a geographically distributed manner, which elevates the impact of the network on the QoS of composited web services. Therefore, a significant research problem in service composition is how to select the best candidate service from a set of functionally equivalent services in terms of a service level agreement (SLA). In this paper, we propose a composition model that takes both QoS of services and cloud network environment into consideration. We also propose a web service composition approach based on genetic algorithm for geo-distributed cloud and service providers who want to minimize the SLA violations.

ADVANCED APPROACH TO WEB SERVICE DISCOVERY AND SELECTION

Web Service Composition (WSC) is a process that helps to save much programming and cost effort by reusing existing components – web services. This process consists of two major stages – Web Service Discovery and Selection (WSD, WSS). This paper presents an overview of current state-of-the-art WSD and WSS methods. It also provides an analysis and highlighting of major problems like lack of support of the syntactical description in fuzzy logic algorithms in WSD and complex approach shortage in WSS problem. Moreover WSC approach and SLA-Aware WSC System are presented.