Service Composition Process Research Articles

Transaction Management in Service-Oriented Systems: Requirements and a Proposal

Service-Oriented Computing (SOC) is becoming the mainstream development paradigm of applications over the Internet, taking advantage of remote independent functionalities. The cornerstone of SOC's success lies in the potential advantage of composing services on the fly. When the control over the communication and the elements of the information system is low, developing solid systems is challenging. In particular, developing reliable web service compositions usually requires the integration of both composition languages, such as the Business Process Execution Language (BPEL), and of coordination protocols, such as WS-AtomicTransaction and WS-BusinessActivity. Unfortunately, the composition and coordination of web services currently have separate languages and specifications. The goal of this paper is twofold. First, we identify the major requirements of transaction management in Service-oriented systems and survey the relevant standards. Second, we propose a semiautomatic approach to integrate BPEL specifications and web service coordination protocols, that is, implementing transaction management within service composition processes, and thus overcoming the limitations of current technologies.

An approach for composite web service selection based on DGQoS

Virtual enterprise is a temporary network of independent companies or enterprises that can quickly bring together to fulfill a value-added task. With the development of Web service technologies, the enterprise business systems can be encapsulated as Web services. Establishing a virtual enterprise is actually a process of Web services composition. As more and more Web services are available, many Web services with different quality of service (QoS) can be found for tasks of the composite Web service. Thus, a significant research problem in Web service composition is how to select the correct Web services for tasks such that the composite Web service gives the best overall quality. In this paper, we propose an approach to achieve Web services selection efficiently with excellent comprehensive quality. Firstly, a comprehensive evaluation model based on generic QoS (GQoS) and domain QoS (DQoS) of composite Web service is established. Secondly, a novel optimization algorithm named culture max–min ant system (C-MMAS) is constructed to solve the problem of Web service selection based on DGQoS. Simulations show that when used in Web service selection, C-MMAS is better than ant colony optimization algorithm and MMAS in efficiency.

Hierarchical Colored Petri Nets Based Modeling and Analyzing for Web Service Composition

Web services composition is a complex and error-prone process, but there are no effective verification mechanisms among the existing composition specifications. Based on the semantics of web services ontology language OWL-S, a formal description and modeling method using Hierarchical Colored Petri nets(HCPN) for web services composition processes is proposed. In the method, the control and data flow information of web services composition process model which is described by the OWL-S can be transformed into HCPN model, with the ease of simulation and verification. On the other hand, the state space explosion problem can be transfered into the memory limit of computer which is not a serious problem now. With the help of CPN-Tools, the established HCPN model can be simulated dynamicly, the dynamic behaviors of the model can be obtained, and the correctness and effectiveness of web services composition can be verified. The method can be used to analyze and verify complex systems. An instance of hospital services is given to illustrate the modeling and analysis of the service composition process with HCPN.

Coordination-theoretic approach to modelling grid service composition process

A grid service composite process is made up of complex coordinative activities. Developing the appropriate model of grid service coordinative activities is an important foundation for the grid service composition. According to the coordination theory, this paper elaborates the process of the grid service composition by using UML 2.0, and proposes an approach to modelling the grid service composition process based on the coordination theory. This approach helps not only to analyze accurately the task activities and relevant dependencies among task activities, but also to facilitate the adaptability of the grid service orchestration to further realize the connectivity, timeliness, appropriateness and expansibility of the grid service composition.

A service-based framework for pharmacogenomics data integration

Data are central to scientific research and practices. The advance of experiment methods and information retrieval technologies leads to explosive growth of scientific data and databases. However, due to the heterogeneous problems in data formats, structures and semantics, it is hard to integrate the diversified data that grow explosively and analyse them comprehensively. As more and more public databases are accessible through standard protocols like programmable interfaces and Web portals, Web-based data integration becomes a major trend to manage and synthesise data that are stored in distributed locations. Mashup, a Web 2.0 technique, presents a new way to compose content and software from multiple resources. The paper proposes a layered framework for integrating pharmacogenomics data in a service-oriented approach using the mashup technology. The framework separates the integration concerns from three perspectives including data, process and Web-based user interface. Each layer encapsulates the heterogeneous issues of one aspect. To facilitate the mapping and convergence of data, the ontology mechanism is introduced to provide consistent conceptual models across different databases and experiment platforms. To support user-interactive and iterative service orchestration, a context model is defined to capture information of users, tasks and services, which can be used for service selection and recommendation during a dynamic service composition process. A prototype system is implemented and cases studies are presented to illustrate the promising capabilities of the proposed approach.

Web Service Composition Survey: State of the Art Review

The Web service composition has received much attention recently to support business-to-business enterprise applications integration. Many composition approaches, languages, platforms, and patents have been proposed to overcome this issue. In this paper we present some of Web service composition languages, platforms, patents, and composition strategies, we compared them to some of the features that must be held by composition process, features such as the dynamic adaptation, execution monitoring, and quality of service (QoS) constraints to satisfy client's requirements to execute Web process. And we give an outlook to essential future research work. Recent patent and research advances aim to find methods for dynamic learning and redesigning along with monitoring and optimization of Web service composition process to satisfy user constraints.

Correlation-aware web services composition and QoS computation model in virtual enterprise

When establishing a virtual enterprise (VE), how some enterprises with different resources and advantages form the alliances by providing respective services to compose the VE for certain profits, it is actually a process of services composition. There always exist a lot of web services with similar functions but different non-functionality properties in the process of web services composition. In order to enhance the quality of service composition, non-functionality properties, i.e., quality of service (QoS) are usually considered. However, most existing works about QoS-based service composition treat the services involved in composition as independent from each other, and their correlations are usually ignored. In fact, most services have some correlations with each other, and the correlations can affect the whole quality of service composition badly. In this paper, three kinds of correlations in services composition are investigated, and a correlation-aware QoS model is studied. The impact of each kind of correlation on the whole QoS of services composition is investigated. A case study indicates that higher quality of services composition can be achieved when considering the correlations among composite services.

Towards runtime discovery, selection and composition of semantic services

Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on-demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end-users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process.

Toward effective service composition for real-time SOA-based systems

Many application domains are increasingly leveraging service-oriented architecture (SOA) techniques to facilitate rapid system deployment. Many of these applications are time-critical and, hence, real-time assurance is an essential step in the service composition process. However, there are gaps in existing service composition techniques for real-time systems. First, admission control is an essential technique to assure the time bound for service execution, but most of the service composition techniques for real-time systems do not take admission control into account. A service may be selected for a workflow during the composition phase, but then during the grounding phase, the concrete service may not be able to admit the workload. Thus, the entire composition process may have to be repeated. Second, communication time is an important factor in real-time SOA, but most of the existing works do not consider how to obtain the communication latencies between services during the composition phase. It is clear that maintaining a full table of communication latencies for all pairs of services is infeasible. Obtaining communication latencies between candidate services during the composition phase can also be costly, since many candidate services may not be used for grounding. Thus, some mechanism is needed for estimating the communication latency for composite services. In this paper, we propose a three-phase composition approach to address the above issues. In this approach, we first use a highly efficient but moderately accurate algorithm to eliminate most of the candidate compositions based on estimated communication latencies and assured service response latency. Then, a more accurate timing prediction is performed on a small number of selected compositions in the second phase based on confirmed admission and actual communication latency. In the third phase, specific concrete services are selected for grounding, and admissions are actually performed. The approach is scalable and can effectively achieve service composition for satisfying real-time requirements. Experimental studies show that the three-phase approach does improve the effectiveness and time for service composition in SOA real-time systems. In order to support the new composition approach, it is necessary to effectively specify the needed information. In this paper, we also present the specification model for timing-related information and the extension of OWL-S to support this specification model.

Web service composition using fluent calculus

This paper presents a new approach for automatic web service composition based on the formalism of fluent calculus. In our approach, the service composition process is viewed as an AI planning problem in the fluent calculus. To semantically describe the services, we have used a 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 Analyser formalism is used. The paper also presents an experimental prototype for the fluent-calculus-based service composition and demonstrates its effectiveness with the help of an application scenario from the social-event planning domain.

Modelling and analysing interoperability in service compositions using COSMO

A service composition process typically involves multiple service models. These models may represent the composite and composed services from distinct perspectives, e.g. to model the role of some system that is involved in a service, and at distinct abstraction levels, e.g. to model the goal, interface or orchestration of some service. The consistency among these models needs to be maintained in order to guarantee the correctness of the composition process. Two types of consistency relations are distinguished: interoperability, which concerns the ability of different roles to interoperate, and conformance, which concerns the correct implementation of an abstract model by a more concrete model. This paper gives an overview of the various types of models that may be used in service composition, and explains when interoperability and conformance need to be assessed during the composition process. The paper further focuses on techniques to describe and analyse the interoperability relation using concepts from the COSMO framework. The choice of COSMO allows one to address both interoperability and conformance within a single conceptual framework. For techniques to describe and analyse the conformance relation reference is made to earlier work. Examples are presented to illustrate how different types of models can be used during the service composition process and how interoperability and conformance among these models can be assessed.

Fault diagnosis for Web service composition based on Bayesian network

A fault diagnosis model based on Bayesian network to identify the most likely problematic services in a Web service composition process was proposed.The Bayesian network topology construction method and the parameters configuration method were specified respectively in detail.A fault diagnosis algorithm based on the Bayesian network was proposed and the algorithm was analyzed.The experimental simulation show that the model can rule out the root cause of the problems in the Web service composition process effectively and efficiently.

A Hybrid Model for Service Selection in Semantic Web Service Composition

One of the most important aspects of semantic web service composition process is the selection of most appropriate semantic web service. The Quality of Service (QoS) and cognitive parameters can be a good basis for this selection process. In this paper, we have presented a hybrid selection model for the selection of semantic web services based on their QoS and cognitive parameters. The presented model provides a new approach of measuring the QoS parameters in an accurate way and provides a completely novel and formalized measurement of different cognitive parameters.

A dual-layered model for web services representation and composition

Nowadays more and more companies and organizations implement their business services in the Internet due to the tremendous progress made recently in the field of Web services. It becomes possible to publish, locate and invoke applications across the Web. Thus, the ability to select efficiently and integrate at runtime services located in different sites on the Web is an important issue. In some situations, if no single Web service can satisfy the request of the user, there should be a possibility to combine existing services together in order to meet the user's request. This paper provides a dual-layered model for web services, where the first model layer captures the high-level functional specifications (namely goals, achievement contexts, and external behaviours), and the second model layer captures the low-level functional specifications (namely interfaces). This model allows the service composition process to be performed on both high-level and low-level specifications. We also introduce the composition operators (both high-level and low-level) to allow composition of virtual services.

Applying Triple Graph Grammars For Pattern-Based Workflow Model Transformations.

Workflow and business process modeling approaches have become essential for designing service collaborations when developing SOA-based systems. To derive actual executable business process descriptions from the high-level workflow models, model transformation techniques can be used. Various service composition and business process languages are available for describing the executable processes. They have been developed having slightly different aims and requirements in mind. They do, however, share common key constructs, called workflow patterns that recur in descriptions given in these languages. We propose a model-driven approach for transforming workflow models given as UML activity diagrams into service composition descriptions. This paper will show how to realize a transformation from UML to BPEL and XPDL with a technology based on Triple Graph Grammars (TGGs). TGGs allow structural relationships between the different model elements to be elegantly expressed in graphical, declarative rules. We will show, in particular, how the commonly known workflow patterns recurring in the different business process languages can act as a guideline for designing the transformation rules. Based on the experiences in this application domain, we furthermore outline ways to enhance the usability and applicability of TGG for this purpose.

A Dynamic Web Services Selection Algorithm with QoS Global Optimal in Web Services Composition

As a new Web pattern, Web service has been rapidly developed in recent years. How to dynamically integrate the existent Web services to form a newly value-added and complex service to meet the requirement of different users is a popular research area. This paper presents an algorithm GODSS (global optimal of dynamic Web services selection) to resolve dynamic Web services selection with QoS global optimal in Web services composition. The essence of the algorithm is that the problem of dynamic Web Service selection with QoS global optimal is transformed into a multi-objective services composition optimization with QoS constraints. The theory of intelligent optimization of multi-objective genetic algorithm is utilized to produce a set of optimal Pareto services composition process with constraint principle by means of optimizing various objective functions simultaneously. Theoretical analysis and experimental results indicate the feasibility and efficiency of this algorithm.

NON-INTRUSIVE MONITORING OF SERVICE-BASED SYSTEMS

This paper presents a framework for monitoring the compliance of systems composed of Web-services with requirements set for them at runtime. This framework assumes systems composed of Web-services which are co-coordinated by a service composition process expressed in BPEL and uses event calculus to specify the requirements to be monitored. These requirements may include behavioral properties of a system which are automatically extracted from the specification of its composition process in BPEL and/or assumptions that system providers can specify in terms of events extracted from this specification.

Providing security for Web Service Composition using Finite State Machine

The revolution impacted by Web Service as a solution to business and enterprise application integration throws light on the significance of security provided by Web Services during Web Service Composition. Satisfying the security requirements is truly a demanding task because of the dynamic and capricious nature of the Web. Web Service Composition associates web services to create high level business process that absolutely matches and conforms appropriately to the service requestor’s needs. It involves customizing services often by locating, assimilating and deploying elementary services. Our paper proposes a policy based system for granting security during the process of web service composition. Policies defined for effective and secure composition analyze and verify the conditions under which the task of the web service is allowed or rejected. To achieve this specification, we make use of Finite State Machine model which clearly portrays the business and flow logic. Nodes in the Finite State Machine represent rules. Upon efficacious fulfillment of policies which are defined in the node access points, transition between rules is stimulated. A service composition is said to be successfully incorporated only if there is complete absence of policy violations when combining the policies of elementary services. The simulated FSM which extracts the rules and policies of the web services and correctly matches and satisfies the policy constraints defined in the access points ensure providing security for the composite web service.

A declarative approach to composing web services in dynamic environments

A recent trend in E-business is the deployment of a variety of web services by product and service vendors to facilitate B2B and B2C E-commerce. To utilize these web services effectively, customer's have to (a) locate each of these services from service directories and retrieve brief service descriptions, (b) analyze service features and evaluate their applicability to the task at hand dynamically, and finally (c) invoke these services in a certain sequence to complete an overall business or personal need. Alternatively, intermediaries execute the aforementioned steps manually and provide a composite service for access from a single service platform. Both these approaches are highly tedious (either for the customer or intermediary) and non-scalable due to the volatility and size of the web. The dynamic nature of the availability and features of web services, real-time requirements on service composition and the large number of alternative combinations of service choices to fulfill a service need makes major demands on the service composition process. This paper presents a novel declarative approach to facilitate dynamic and scalable web service composition called Integrated Service Planning and Execution (ISP&E) based on AI planning techniques. Implementation of an architecture for dynamic web service composition and execution based on a domain-independent AI planning framework called Hierarchical Task Network (HTN) planning is described in this paper. Simulated experiments highlight the effectiveness of our proposed approach which interleaves service composition and execution, to cope with dynamic service capabilities and service volatility.