A Framework for Dynamic Web Services Composition

Dynamic composition of web services is a promising approach and at the same time a challenging research area for the dissemination of service-oriented applications. It is widely recognised that service semantics is a key element for the dynamic composition of Web services, since it allows the unambiguous descriptions of a service's capabilities and parameters. This paper introduces a framework for performing dynamic service composition by exploiting the semantic matchmaking between service parameters (i.e., outputs and inputs) to enable their interconnection and interaction. The basic assumption of the framework is that matchmaking enables finding semantic compatibilities among independently defined service descriptions. We also developed a composition algorithm that follows a semantic graph-based approach, in which a graph represents service compositions and the nodes of this graph represent semantic connections between services. Moreover, functional and non-functional properties of services are considered, to enable the computation of relevant and most suitable service compositions for some service request. The suggested end-to-end functional level service composition framework is illustrated with a realistic application scenario from the IST SPICE project

Web services composition, execution and visualization.

Visualization; International;

QoS-Aware Middleware for Web Services Composition

The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online Business-to-Business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different Quality of Service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming

Semantic web services composition

Web services are becoming the most predominant paradigm for distributed computing and electronic business. They are self-contained Internet accessible applications that are capable not only of performing business activities on their own, but they also possess the ability to engage with other Web services in order to build new value-added services. Both academic and industrial bodies have been investigating issues regarding service descriptions, discovery and invocation, but automated service composition was somewhat neglected. The latter involves automated methods for constructing a sequence of Web services to achieve a desired goal. In this work we present initial research that focuses on the issue of automated service composition in conjunction with the Semantic Web. In this report we propose a composition engine that will automatically handle the integration of Web services through the use of a Web service description language such as DAML-S, the planning of workflow definitions, scheduling of tasks, status monitoring of the execution process, handling of faults and communication with other entities such as user agents, service registries and other composition engines.peer-reviewe

Dynamic Web Services Composition

Emerging web services technology has introduced the concept of autonomic interoperability and portability between services. The number of online services has increased dramatically with many duplicating similar functionality and results. Composing online services to solve user needs is a growing area of research. This entails designing systems which can discover participating services and integrate these according to the end user requirements. This thesis proposes a Dynamic Web Services Composition (DWSC) process that is based upon consideration of previously successful attempts in this area, in particular utilizing AI-planning based solutions. It proposes a unique approach for service selection and dynamic web service composition by exploring the possibility of semantic web usability and its limitations. It also proposes a design architecture called Optimal Synthesis Plan Generation framework (OSPG), which supports the composition process through the evaluation of all available solutions (including all participating single and composite services). OSPG is designed to take into account user preferences, which supports optimality and robustness of the output plan. The implementation of OSPG will be con�gured and tested via division of search criteria in di�erent modes thereby locating the best plan for the user. The services composition and discovery-based model is evaluated via considering a range of criteria, such as scope, correctness, scalability and versatility metrics

Conversations for Web services composition

This paper presents how conversations are integrated into Web services composition. While much of the recent work on Web services has focussed on low-level standards for publishing, discovering, and triggering them, this paper promotes Web services to the level of active components. Such components engage in conversations, make decisions, and adjust their behavior according to the context of the situations in which they participate. Conversations between Web services are specified with state chart diagrams enhanced with context-awareness mechanisms. © Springer-Verlag Berlin Heidelberg 2005

Reconciling Semantic Heterogeneity in Web Services Composition

Service Oriented Computing (SOC) is a popular computing paradigm for the development of distributed Web applications. Service composition, a key element of SOC, is severely hampered by various types of semantic heterogeneity among the services. In this paper, we address the various semantic differences from the context perspective and use a lightweight ontology to describe the concepts and their specializations. Atomic conversions between the contexts are implemented using XPath functions and external services. The correspondences between the syntactic service descriptions and the semantic concepts are established using a flexible, standard-compliant mechanism. Given the naive BPEL composition ignoring semantic differences, our reconciliation approach can automatically determine and reconcile the semantic differences. The mediated BPEL composition incorporates necessary conversions to convert the data exchanged between different services. Our solution has the desirable properties (e.g., adaptability, extensibility and scalability) and can significantly alleviate the reconciliation efforts for Web services composition.This work was partially supported by the MIT Sloan China Management Education Project and grants from the National Natural Science Foundation of China (No. 60674080 and No. 60704027) and the National High-Tech R&D (863) Plan of China (No. 2007AA04Z150)