Proactively Composing Web Services as Tasks by Semantic Web Agents

This chapter presents the framework for agent-enabled dynamic composition of Semantic Web services. The approach and the framework have been developed in several research and development projects by ISRG and IOG. The core of the methodology is the new understanding of a Semantic Web service as a capability of an intelligent software agent supplied with the proper ontological description. It is demonstrated how diverse Web services may be composed and mediated by dynamic coalitions of software agents collaboratively performing tasks for service requestors. Middle agent layer is introduced to conduct the transformation of a Web service request to the corresponding task, agent-enabled cooperative task decomposition and performance. Discussed are the formal means to arrange agents’ negotiation, to represent the semantic structure of task-activity-service hierarchy and to assess fellow-agents’ capabilities and credibility factors. It is argued that the presented technique is applicable to various application domains. Presented is the ongoing work on designing and implementing agent-based layered architecture for intelligent rational information and document retrieval. Finally, the discussion of the OntoServ.Net framework for the development of P2P mobile service infrastructures for industrial asset management provides the extension of the Web service composition approach.

QoS-Aware Web Services Discovery with Federated Support for UDDI

Web services’ discovery mechanism is one of the most important research areas in Web services because of the dynamic nature of Web services. In practice, UDDI takes an important role in service discovery since it is an online registry standard to facilitate the discovery of business partners and services. However, QoS related information is not naturally supported in UDDI. Service requesters can only choose good performance Web services by manual test and comparison. In addition, discovery among private UDDI registries in a federation is not naturally supported. To address these problems, we propose UDDI extension (UX), an enhancement for UDDI that facilitates requesters to discover services with QoS awareness. In this system the service requester invokes and generates feedback reports, which are received and stored in local domain’s UX server for future usage. By sharing these experiences from those requesters in the local domain, the UX server summarizes and predicts the service’s performance. A general federated service is designed to manage the service federation. The discovery between different cooperating domains is based on this general federated service, and therefore the links between domains are maintained dynamically. The system handles the federated inquiry, predicates the QoS difference among different domains, and provides a simple view over the whole federation. Meanwhile, the UX server’s inquiry interface still conforms to the UDDI specification.

Web Services Enabled E-Market Access Control Model

With the dramatic expansion of global e-markets, companies collaborate more and more in order to streamline their supply chains. Small companies often form coalitions to reach the critical mass required to bid on large volume or wide ranges of products. Meanwhile, they also compete with one another for market shares. Because of the complex relationships among companies, controlling the access to shared information found in e-markets is a challenging task. Currently, there is a lack of comprehensive access control approaches that can be used to maintain data security in e-markets. We propose to integrate several known access control mechanisms such as role-based access control, coalition-based access control, and relationship driven access control into an e-market access control model (EMAC). In this chapter, we present a Web services-based architecture for EMAC and the associated concepts and algorithms. We also illustrate, via an automotive e-market example, how the EMAC model can support e-market access control.

Architectural Foundations of WSRF NET

State management has always been an underlying issue for large scale distributed systems, but it has only recently been brought to the forefront of Grid computing with the introduction of the Web services resource framework (WSRF) and its companion WS-notification. WSRF advocates standardized approaches for client exposure to and potential manipulation of stateful services for Grid computing; however, these arguments and their long term implications have been difficult to assess without a concrete implementation of the WSRF specifications. This chapter describes the architectural foundations of WSRF.NET, which is an implementation of the full set of specifications for WSRF and WS-notification on the Microsoft .NET framework. To our knowledge, the observations and lessons learned from the design and implementation of WSRF.NET provide the first evaluation of the WSRF approach. A concrete example of the design, implementation and deployment of a WSRF-compliant service and its accompanying WSRF-compliant client are used to guide the discussion. While the potential of WSRF and WS-notification remains strong, initial observations are that there are many challenges that remain to be solved, most notably the implied programming model derived from the specifications, particularly the complexity of service-side and client-code and the complexity of WS-notification.

Authentication Techniques for UDDI Registries

A Web service is a software system designed to support interoperable application-to-application interactions over the Internet. Web services are based on a set of XML standards, such as Web services description language (WSDL), simple object access protocol (SOAP) and universal description, discovery and integration (UDDI). A key role in the Web service architecture is played by UDDI registries, i.e., a structured repository of information that can be queried by clients to find the Web services that better fit their needs. Even if, at the beginning, UDDI has been mainly conceived as a public registry without specific facilities for security, today security issues are becoming more and more crucial, due to the fact that data published in UDDI registries may be highly strategic and sensitive. In this chapter, we focus on authenticity issues, by proposing a method based on Merkle hash trees, which does not require the party managing the UDDI to be trusted wrt authenticity. In the chapter, besides giving all the details of the proposed solution, we show its benefit wrt standard digital signature techniques.

RAWS & UWAS

Reflection is a powerful technology that allows us to produce auto-adaptable software. RAWS is a reflective, multilevel Web service architecture aimed at allowing a Web service to transform its structure and behaviour without the need of human intervention to change the source code, compile it or deploy it again on the application server. Using RAWS, the Web service can change itself automatically. Current application servers have a very important limitation: The deployment platform (J2EE, .NET, etc.). Using current servers, a Web service or application can only be deployed on a server which runs with the same technology. To solve this drawback, we have developed universal Web application server (UWAS), platform capable of deploying Web services or applications written in any object-oriented language or for any platform. This is possible thanks to the fact that UWAS internally uses a language-independent object-oriented Web server markup language (OOWSML) representation based on XML. Altogether, RAWS & UWAS make it possible to deploy a Web service on the server regardless of its implementation technology, providing the flexibility to automatically adapt or transform the Web service structure and/or behaviour.

Advanced Data Compression Techniques for SOAP Web Services

A major drawback of using SOAP for application integration is its enormous demand for network bandwidth. Compared to classical approaches, like Java-RMI and Corba, SOAP messages typically cause more than three times the network traffic. In this chapter we will explore compression strategies and give a detailed survey and evaluation of state of the art binary encoding techniques for SOAP. We also introduce a new experimental concept for SOAP compression based on differential encoding, which makes use of the commonly available WSDL description of a SOAP Web service. We not only conduct a detailed evaluation of compression effectiveness, but also provide the results of execution time measurements.

Dynamically Adaptable Web Services Based on the Simple Object Access Protocol

Dynamic protocol stacks enable a developer to select a particular protocol profile at bind time where each protocol profile is built from a rich library of protocol modules including UDP, packet loss detection, data encryption, TCP, Multicast among others. Communicating objects can be represented as object graphs that together realise the required behaviour built upon the IP service offered by the host computer. All protocols down to device driver level can be implemented at the user level, providing the maximum potential for configurability. The simple object access protocol (SOAP) is a lightweight remote procedure calling (RPC) protocol for the exchange of structured data in a decentralized environment. SOAP enables programs to run and interoperate with other SOAP applications (called Web services) in a distributed environment. The SOAP protocol is based on extensible markup language (XML) and hypertext transmission protocol (HTTP), which, it is claimed, makes it a language and platform neutral vehicle for RPC over the Internet and through firewalls. This chapter describes a SOAP Web service deployed which enables clients to download protocol stack components as simple MIME attachments.

Challenges and Opportunities for Web Services Research

Web services are becoming a major research topic for computer scientists, engineers and business consulting professionals. In this preface, I would like to outline the challenges of the current Web services research topics from the modeling, interoperability, and mathematical foundations points of view. Then I will introduce some research opportunities and possible future directions for moving Web services forward via some illustrative ideas such as business semantic computing as well as killer application driven Web services research approaches. For the business semantic computing aspect I will present some example application domains such as federated Web services discovery, dynamic Web services composition and extended business collaboration.

Metadata-Based Information Management Framework for Grids

Information service is a key component of a Grid environment and crucial to the operation of Grids. This chapter presents an information management framework for a Grid virtual organization (VO). This information management framework is a hierarchical structure which consists of VO layer, site layer and resource layer. We propose different models of information data organization for information management in Grids and simulation experiments were conducted to evaluate the performance of these models. Based on the experimental results, we further introduce the data organization model for our information management framework. A performance evaluation conducted on a cross-domain Grid testbed indicates that our information management framework presents good scalability with large number of concurrent users and large amount of information aggregated. In this chapter some application experiences of using the information management framework are also presented.