Web Service Composition Research Articles

A Partial Pre-composing Method for Composition of Web Services

In recent years, web service compositions are deemed to be one of the new technologies to build an application system. By composing independent web services, loosely coupled services are integrated into value-added service compositions. In this paper, we address the web service composition problem and propose a partial pre-composing approach. This approach picks and generates popular user requests as service combinations stored in the service repository. We compare our approach with QoS driven, extended A* and Graphplan methods, the experimental results indicate that our algorithm can return a solution with fewer web services or less execution time.

A semantic assessment framework for e-learning systems

Semantic web technologies are applied in a wide spectrum of applications including search engines, web services discovery and composition, semantic tags and electronic assessment of e-learning systems. Recently, the field of electronic assessment has grabbed the attention of many researchers. Electronic assessment is a real challenge taking to consideration the diversity of question types. E-assessment of answers to open questions has created new challenges regarding extracting students' answers using natural language processing techniques and infer new knowledge using description logic reasoning. To be able to automate the process of assessing the students' answers, they have to be annotated with semantics. This paper presents a thorough survey of significant research efforts that adopt semantic annotation to enhance the process of e-assessment. Moreover, in this paper, we propose a semantic-based framework that automates the process of electronically assessing the answers of questions on e-learning systems based on their semantic descriptions.

Towards a Performance Analysis of Composite Web Services using Petri Nets.

The proliferation of web services-based applications, collaboration, interoperability between companies, and more generally demands of web services over the internet are major challenges in the design of performance evaluation in web services discovery and composition. It is required for the web services providers to analyse the performance related to the satisfaction of clients requests. This paper presents an analytical model based on Petri nets, for evaluating the performance of a web services system where requests and web services follow an exponential server. The arrival process of the users requests and web services follows a Poisson distribution. When the web services finish the service, they join the queue. This model follows a Poisson distribution, it is based on Petri nets. We use an analytical method for solving the model. Furthermore, we compute the system's response time, and the average number of clients in the system in terms of the arrival rate of clients requests. We find the limit number of clients in the system from which it begins to be saturated.

Optimisation of automatic web services composition using genetic algorithm

In recent years, with the expansion of organisations, service-oriented architecture is known as an effective tool for creating applications. Hence, the need to use web services in organisations to reduce costs is felt more than ever. The purpose of web service composition is to determine a proper mix of user requests that cannot be met by a simple web service. In this paper, a genetic-based algorithm is proposed for combining cloud services that ensures multiple clouds work efficiently. The proposed method also provides an overview of the weaknesses of other available methods in terms of computational complexity in automated selection of web services and makes it possible to fulfil the demands of the composition of web services in a more optimal way. It is worth noting that the simulation results show the superiority of the proposed method compared to other methods analysed in the paper.

A model-driven approach for the verification of an adaptive service composition

The development of web service compositions is a complex task that needs coherent mechanisms in order to maintain the quality of the provided business process and to satisfy user needs. This paper proposes a development process of an adaptable composed web service and mainly focuses on the reliability and the performance properties. It explores the model driven architecture transformation technique in order to formally model the whole service orchestration using the timed coloured Petri net formalism. The software CPN Tools offers, among others, the ASK-computational tree logic, the model checking technique and several monitors that will be exploited to describe and verify different properties at design time. They will also be used via access/CPN library in order to reason about the reconfiguration technique at runtime. An example of an identity card management process is given to prove the feasibility of the proposed solution.

An attempt to enhance the time of reply for web service composition with QoS

The web services are the commonly prevailing service clusters of the service-oriented framework (SOA) and service related assessments. The disputes are related to the quality of service (QoS) for choosing web services freely and creating a collection of web services for carrying out trades. The ultimate aim is to choose web services based on the non-functional features and quality of service (QoS) ranks. In order to choose a web service for every process a social aspect web (SAW) scheme is employed which does not comprehensively make use of all sorts of web services. It employs the requirements of the user for ranking web service set of the applications and finally provides SAW schemes over a set of web service applicants. The mechanism helps in selecting the web services in terms of quality of services (QoS) scores and user needs. The choice of web services over varied web services based on scheme can be utilised for aggregation and organising web services resulting in optimised time of reply to the web service actions.

Testing Web Service Compositions: Approaches, Methodology and Automation

Testing Web Service Compositions: Approaches, Methodology and Automation

An attempt to enhance the time of reply for web service composition with QoS

The web services are the commonly prevailing service clusters of the service-oriented framework (SOA) and service related assessments. The disputes are related to the quality of service (QoS) for choosing web services freely and creating a collection of web services for carrying out trades. The ultimate aim is to choose web services based on the non-functional features and quality of service (QoS) ranks. In order to choose a web service for every process a social aspect web (SAW) scheme is employed which does not comprehensively make use of all sorts of web services. It employs the requirements of the user for ranking web service set of the applications and finally provides SAW schemes over a set of web service applicants. The mechanism helps in selecting the web services in terms of quality of services (QoS) scores and user needs. The choice of web services over varied web services based on scheme can be utilised for aggregation and organising web services resulting in optimised time of reply to the web service actions.

Q-Graphplan: QoS-Aware Automatic Service Composition With the Extended Planning Graph

With the progress of web technologies, web services with abundant functionalities, such as video transmission, location, navigation, etc., are becoming more and more pervasive. Automatic web service composition aims to automatically combine selected elementary web services from a finite service set by matching the input and output parameters given an initial state and a goal state. Considering the end-to-end Quality-of-Service(QoS) of each web service, the service composition problem becomes an optimization problem to find the optimal solution. This paper maps this problem to an automatic planning problem and proposes Q-Graphplan based on the classical graphplan, an efficient planner for solving classical planning problems. First, we construct a planning graph based on the dependency relationships of the web services and extract essential heuristics according to the reachability analysis. Second, we convert this planning graph to a directed path generation graph. Finally, we extract the optimal solution from the path generation graph using a backward A* algorithm with the heuristics of the planning graph. Furthermore, our approach avoids redundancies when constructing the planning graph and improves the searching effectiveness in extracting solution. We conduct experiments on the WSC-2009 dataset to compare performance against present approaches, and the results show the efficiency and effectiveness of our proposed approach.

IWSN: A novel method for modeling the interaction of web services

As the most notable implementation of service-oriented architectures, web services has brought some challenging research issues, one of which is the composition. Correct interaction among web services is the prerequisite of their successful composition. In this paper, we propose a novel approach to model dynamic interactive behavior of web services, aiming to effectively take advantage of the flexibility of service composition technology and guarantee the behavior compatibility of web services and further to facilitate the application of web service composition in healthcare field. An interaction model of web services based on Kahn process network (KPN) is presented in this paper, which is a data-flow and channel-based model supporting parallel and cooperative computation. Formal behavioral semantics of this model is defined by Pi-calculus process algebra and formal properties of the proposed model are discussed. An application case is demonstrated to illustrate how the proposed model can be applied to describe services behavior and their interaction. The reachability analysis of the application case is performed based on modal -calculus. How the supporting tool, i.e. CWB-NC, can be utilized to verify the properties we anticipate is presented.

A Meta-Heuristic-Based Approach for Qos-Aware Service Composition

Recently, with the rapid increase in the number of web services, QoS-aware Web Service Composition(QWSC) has become a popular topic in both industry and academia. Meta-heuristic algorithm, as an effective way to solve classical optimization problems, has been successfully applied to QWSC nowdays. However, such approach has intrinsic drawbacks and usually lack of good performance in large-scale scenarios. For example, some meta-heuristic algorithms are suitable for continuous search space, while the search space of QWSC is discrete. For solving those problems which were commonly faced when applying meta-heuristic algorithm on QWSC, in this research, we firstly introduce a preprocessing approach for constructing fuzzy continuous neighborhood relations of concrete services, which makes the local search strategy of meta-heuristic algorithms be as effective in discrete space as in continuous space, thus improving the optimization performance. Second, we combine Harris Hawks Optimization (HHO) algorithm and logical chaotic sequence to propose an improved meta-heuristic algorithm named CHHO for solving QWSC. The ergodic and chaotic characteristics of chaotic sequences are used to enhance the ability of the CHHO to jump out of the local optimum for further optimization. Experimental results show that the CHHO has better optimization performance by comparing with the existing mainstream algorithms when solving QWSC problems. Additionally, the preprocessing approach not only greatly improves the optimization performance of the CHHO but also can be freely utilized in other meta-heuristics based approaches.

Self-healing of web service compositions: a specification rewriting approach

Self-healing of web service compositions: a specification rewriting approach

Towards a performance analysis of composite web services using Petri nets

The proliferation of web services-based applications, collaboration, interoperability between companies, and more generally demands of web services over the internet are major challenges in the design of performance evaluation in web services discovery and composition. It is required for the web services providers to analyse the performance related to the satisfaction of clients requests. This paper presents an analytical model based on Petri nets, for evaluating the performance of a web services system where requests and web services follow an exponential server. The arrival process of the users requests and web services follows a Poisson distribution. When the web services finish the service, they join the queue. This model follows a Poisson distribution, it is based on Petri nets. We use an analytical method for solving the model. Furthermore, we compute the system's response time, and the average number of clients in the system in terms of the arrival rate of clients requests. We find the limit number of clients in the system from which it begins to be saturated.

Automation of Web Services Composition Development Cycle

Since the emergence of Service Oriented Architecture and its implementation with the Web services technology, combining several Web services to response to a complex request presented a hard challenge. This is an area that has attracted the interest of many research organizations and manufactories. This paper firstly presents a summary of developed approach of Web services composition based on Model Driven Approach, and using different languages and systems, like Multi-Agent Reactive Decisional system for modeling task, Lotos language for formal verification, and Business Process Execution language for implementation. Secondly, the paper seeks to automate the generation of different processes (business process, executable process and formal process) by using the framework AWSCPM «Automatic Web Services Composition Processes based on MARDS», which is developed as part of this research work.

AN INTEGRATED THREE-FLOW APPROACH FOR FRONT-END SERVICE COMPOSITION

End-User Service Composition (EUSC) aims to enable end-user programmers who are not professional developers develop applications by composing or aggregating existing web services. Despite the effort, studies have shown that, end-user programmers are not able to deal with the technical complexities involved in EUSC. One way to deal with this issue is Front-End Service Composition (FESC), which allows end-user programmers to compose web services at the presentation layer of an application by configuring user interface (UI) widgets that represent the back-end web services. However, there are not many studies on FESC and the existing ones suffer two main problems, namely, lack of control flow and/or application flow visualization, and they still require end-user programmers to have certain technical knowledge in the service composition process that these end-user programmers generally do not possess. Following that, this study proposes an integrated three-flow approach (application flow, control flow and data flow) to deal with the current limitations of FESC. The approach generates the GUI of web services automatically, thus allowing the UI of the application to be developed at the same time the required web services are assembled. The approach allows end-user programmers to explicitly configure the three different types of flows involved in service composition. A proof-of-concept prototype, QuickWSC, that incorporates the three-flow approach was developed. It adopts a side-by-side multiple-view design to support visual configuration of the three flows in an uncluttered yet synchronized manner that adhered to established design guidelines. A user evaluation study was conducted on QuickWSC. The results show that it is easy to compose web services by explicitly specifying the three flows, that the configurations of the three flows integrated in the two views helps in composing application from web services, and that no technical knowledge is required to use QuickWSC

Semantic web service composition using semantic similarity measures and formal concept analysis

One of the main assets of the Service Oriented Architecture (SOA) is composition, which consists in developing higher-level services by re-using well-known functionality provided by other services in a low-cost and rapid development process. In this paper, we present IDECSE a new integrated approach for composite services engineering. By considering semantic Web services, IDECSE addresses the challenge of fully automating the classification, discovery and composition while reducing development time and cost. The classification and the discovery processes rely on adequate semantic similarity measures. Both semantic and syntactic descriptions are integrated through specific techniques for computing similarity measures between services. Formal Concept Analysis (FCA) is used then to classify Web services into concept lattices in order to facilitate relevant services identification. A graph based semantic Web service composition process was proposed within the IDECSE framework. Using semantic similarities in grouping classes of services and in composing services shows a significant improvement compared to other approaches.

Modeling and Implementation of Web Services Composition Based on MARDS

Modeling and Implementation of Web Services Composition Based on MARDS

Web service discovery with incorporation of web services clustering

With the rapid growth and adoption of web-based technologies, more and more service providers offer various services on the web. This can facilitate the organizations to develop business applications using web services composition over the Internet according to their business requirements. The primary requirement for developing composite web service is to discover the most relevant web service for realizing each function of the required composite web service. Finding the most relevant web service is still a challenging task. In this paper, we propose web service discovery approach that incorporates web services clustering. Clustering technique combines latent Dirichlet allocation(LDA) and k-Medoids and reduces search space for web service discovery. Web service discovery uses a match-making algorithm that utilizes WordNet database and Hungarian method to compute the semantic similarity score for a web service based on the requested query. Experimental results show that the proposed approach performs better than LDA-based approach.

End-to-end information flow security for web services orchestration

Multi-party interactions in Web Service (WS) composition are hard to managed and difficult to design and verify, especially while end-to-end information flow security (IFS) must be respected. Usually, IFS is guaranteed for a data originator and ultimate recipient WS, however inter-organizational service compositions involve partners that do not necessarily share the same level of security, especially for data they do not generate nor process themselves. In this paper, we focus on the non-interference property and we present a correct-by-construction approach to build orchestrated WSs with multi-party interactions. A key ingredient of this approach is to present the system composition at an abstract level as a component-based model where the IFS verification and the system configuration are considered at early stage. When this configuration is validated, that is, no security leak is detected, we automatically generate orchestrator components that handle IFS. Afterwards, we generate accordingly BPEL processes where the IFS constraints are enforced as security WS-policies in the BPEL description of services. We develop a set of tools that automate the approach and we validate the effectiveness of our approach with well known Web service use cases.

A Development of AWSCPM Framework for Automation of Web Services Composition Processes

A Development of AWSCPM Framework for Automation of Web Services Composition Processes