Web Service Composition Optimization Based on Improved Artificial Bee Colony Algorithm

To deal with the problems such as Web Services selection algorithm, availability of Web Services composition and QoS(Quality of Service) guarantee, presents a model for Web Services composition based on QoS and providers' benefit. In this model, the traditional UDDI is expanded to describe the QoS attributes of Web Services. A Service Proxy role is added into this model. All Web Services compositions requested by service consumers are fond, bound and invoked by the Service Proxy role. In order to maximize services providers' benefit, presents a Service Request Queue Scheduling algorithm in the Service Proxy role. This model meets the QOS requirements of service consumers, guarantees the availability of Web Services composition and maximizes service providers' benefit. Experimental results confirm the efforts of this model.

To deal with Failure classification and code winding,a fault-tolerant model of web service composition based on aspect oriented programming is proposed.Firstly,fault reasons at all stage of Web services during execution are analyzed and classified,appropriate fault-tolerant strategies are presented,and web service composition model are built based on separation-of-concerns.Business function and quality of service are ensured,while function concerns and fault-tolerant concerns are separated.Finally,a case study of setup planning is presented to verify the feasibility of the method.

Web service development and composition are mainly realized using programming languages. The high demand of productivity in the development of composite Web service requires different approaches. Conceptual modeling could be a solution. In this work we present an approach to conceptual modeling of Web service composition. Considering that a composite Web service is a way of implementing functionality reuse, we propose to use aggregation and specialization relationships (at conceptual level) with a precise semantics as mechanisms to allow the composition characterization. These conceptual models could be included in other methods (as Web engineering methods) or models in order to capture the integration requirements needed to define collaborative applications.

In the Web Service Composition (WSC) domain, Web Services (WSs) execute in a highly dynamic environment, as a result, the Quality of Service (QoS) of a WS is constantly evolving, and this requires tracking of the global optimization overtime to satisfy the users’ requirements. In order to make a WSC adapt to such QoS changes of WSs, we propose a self-healing model for WSC. Self-healing is the automatic discovery, and healing of the failure of a composite WS by itself due to QoS changes without interruption in the WSC and any human intervention. To the best of our knowledge, almost all the existing self-healing models in this domain substitute the faulty WS with an equivalent one without paying attention to the WS selection processes to achieve global optimization. They focus only on the WS substitution strategy. In this paper, we propose a self-healing model where we use our hybrid approach to find the optimal WSC by using Parallel Genetic Algorithm based on Q-learning, which we integrate with K-means clustering (PGAQK). The components of this model are organized according to IBM’s Monitor, Analyse, Plan, Execute, and Knowledge (MAPE-K) reference model. The PGAQK approach considers as a module in the Execute component. WS substitution strategy has also been applied in this model that substitutes the faulty WS with another equivalent one from a list of candidate WSs by using the K-means clustering technique. K-means clustering is used to prune the WSs in the search space to find the best WSs for the environment changes. We implemented this model over the NET Framework using C# programming language. A series of comparable experiments showed that the proposed model outperforms improved GA to achieve global optimization. Our proposed model also can dynamically substitute the faulty WSs with other equivalent ones in a time-efficient manner

As the capability of an individual Web service is limited, it's necessary to create new functionalities with existing Web services. Web services composition is the ability to create a new value-added service by incorporating some existing Web services together. An important challenge for Web services composition is how to ensure the correctness and reliability of the WS-BPEL (Web services business process execution language) process and the composition. A graphical and formal modeling tool suitable for solving this problem is CPN (Colored Petri net), which provides formal semantics and a number of analysis techniques for modeling and verifying web services composition. This paper proposes a CPN-based model for web services composition, describes how to translate WS-BPEL to CPN model, and discusses the analysis and verification of services composition. The model enables efficient composition of Web services and validates the correctness of composition by formal verification.

Modeling and Verification of Response Time of QoS-aware Web Service Composition by Timed CSP

The goal of the Web service composition (WSC) problem is to find an optimal composition of web services to satisfy a given request using their syntactic and/or semantic features. In this paper, in particular, we study the Quality of Services (QoS)-driven WSC problem to optimize service quality criteria, e.g., response time and/or throughput. We propose a novel solution based on Learning-based Depth First Search (LDFS). Given a set of web service descriptions including QoS information and a requirement web service, we reduce the QoS-driven WSC problem into a planning problem on a state-transition system. We then find the optimal solution for the problem using a dynamic programming based on LDFS which recently has shown a promising result.

Traditional formal method has been solved the problems of functional modeling and verification of Web service composition, but it could not effectively analyze and calculate the costs of the service composition. A minimum cost composition algorithm based on process algebra CSP is proposed. The algorithm first translates the XML format Web service composition description to CSP format formal description. According to the trace model of the CSP, the executive paths for the proper composition schemes can be found. Finally, the total cost of the composition schemes can be solved out according to the cost of the single event in the web services' interfaces. A case study is presented that shows the algorithm can effectively calculate the total costs of the composition schemes, and the optimal scheme can be pick out refer to the results.

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.

The paper summarizes current technologies of dynamic web service composition. Then, based on the existing technologies, we raise a new solution for dynamic web service composition. We make use of the knowledge of domain ontology. On the one hand, the user’s requirement was broken down into a series of abstract web services, according to the logic of business processes. On the other hand, through establishing the web service index storehouse, we gather the existing atomic services and composite services in domain ontology. By semantic matching between the abstract services and the atomic services or the composite services, the executable web services composition could be obtained. Finally, an application example of the solution is showed.

In the environment of Internet of things, devices are encapsulated as web services and device operations are encapsulated as web service methods. These web services are stateful because devices can't be controlled by more than one client at the same time. Traditional web service composition methods are lack of considering state of the web services and have great challenge under Internet of things. In this paper, a three-layer model for modeling stateful web services composition based on extended Petri net is proposed. It includes web services layer, ws-resource layer and process layer. A method of a web service is abstracted as a ws-resource. There are two types of ws-resources: exclusive resources can be invoked serially, non-exclusive resources can be invoked simultaneously. In this model, a web service is associated with one or more ws-resources, a web service can be invoked only when all needed ws-resources are available. Finally an example is demonstrated to illustrate how this model works.

Web Services Composition (WSC) is one of the main benefits of Service Oriented Architecture (SOA), however, its optimization is still a highly discussed research topic. In order to have an optimal composition, and therefore the best composite service, the composition mechanism must meet the requirements and issues of this process. Among the most important needs, we focus on the quality of web services involved, since the functional properties are not sufficient to determine the most appropriate service to meet the business goal. Researchers in this area propose different approaches and architectures to integrate Quality Of Service (QoS) values as a selection criterion, but they don't mention how to automatically generate those information and they don't consider the QoS values variations. They evaluate the QoS once and use calculated values in a static way. In our research work, we propose to automate the web service database filling. So, we don't have to manually read the WSDL file and extract necessary information for each operation. Moreover, we propose a QoS monitor component to calculate and update stored QoS values.

To enforce reliability of composite Web Services at run-time, this paper proposes a transaction management model based on Compensation Planning Graph for Web Service composition. First, a web service composition model with transactional properties is introduced. Second, in order to handle transaction when exceptions are occurred, compensation dependency relationships and Compensation Planning Graph is introduced, and an algorithm of automatic generation of compensation dependency relationships and transaction handling based on CPG is proposed. Finally, evaluation methods of QoS of web services and user satisfaction of transaction handling are given. During the execution of composite web services, this approach can guarantee compensation achieving through forward- or backward-compensation. In addition, in this model, a novel concept named Transfer Service is proposed to solve the problem that there are no compensation services or unsuccessful retriable services after many retry times. This model and method can improve self-adjustability and stability of composite services in the course of deployment and execution. Simulations prove that this approach can efficiently guarantee the reliability of composite services at run-time.

This paper proposes the concept of business events as the cornerstone to web service description and coordination. First, a web service architecture is introduced as the result of an event based analysis & design phase. Then, it is advocated how the event concept can be used for semantically rich web service description. A distinction is made between two web service interfaces: a non-transactional query interface and a transactional event notification interface. Furthermore, a web service composition model is proposed, based on event broadcasting and event preconditions, instead of traditional one-to-one method invocations. The composition model is presented in a static variant and in a version with dynamic subscription. Throughout the paper, it is shown how the event based approach fits entirely within the current standard SOAP/WSDL/UDDI web services stack.KeywordsRemote ServiceQuery InterfaceMethod InvocationInput ServiceBusiness EventThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

A lot of work have been carried out to find the efficient algorithms for QoS-aware dynamic web service composition. The multi-objective multi-choice problem as an evolutive multi-dimension multi-objective 0-1 knapsack problem (MMKP) can be reduced into the web service composition with multiple QoS constraints, while many approaches based on ant colony optimization (AOC) have been introduced in order for solving MMKP. This paper presents a novel QoS-aware dynamic web service composition optimization algorithm with improved AOC. The essence of the algorithm is that the problem of dynamic web service selection with QoS global optimality is transformed into a multi-objective multi-choice QoS-aware web services composition optimization (an evolutive MMKP), for the final purpose of our algorithm is to achieve Pareto Optimality.