Aphrodite Tsalgatidou

An Overview of Standards and Related Technology in Web Services

The Internet is revolutionizing business by providing an affordable and efficient way to link companies with their partners as well as customers. Nevertheless, there are problems that degrade the profitability of the Internet: closed markets that cannot use each others services; incompatible applications and frameworks that cannot interoperate or built upon each other; difficulties in exchanging business data. Web Services is a new paradigm for e-business that is expected to change the way business applications are developed and interoperate. A Web Service is a self-describing, self-contained, modular application accessible over the web. It exposes an XML interface, it is registered and can be located through a Web Service registry. Finally, it communicates with other services using XML messages over standard Web protocols. This paper presents the Web Service model and gives an overview of existing standards. It then sketches the Web Service life-cycle, discusses related technical challenges and how they are addressed by current standards, commercial products and research efforts. Finally it gives some concluding remarks regarding the state of the art of Web Services.

Business models and transactions in mobile electronic commerce: requirements and properties

Abstract Advances in wireless network technology and the continuously increasing number of users of hand-held terminals make the latter a possible channel for offering personalized services to mobile users and give pace to the rapid development of mobile electronic commerce (MEC). MEC operates partially in a different environment than Internet e-commerce due to the special characteristics and constraints of mobile terminals and wireless networks and the context, situations and circumstances in which people use their hand-held terminals. In this paper, we discuss the business models in MEC and transaction modeling issues pertinent for the business models and the environment.

Integrated value chains and their implications from a business and technology standpoint

Unlike previous decades where enterprises prized independence, the next decade will be one of business alliances and competing, end-to-end value chains. Enterprise value chains comprised of powerful business alliance partners will exceedingly compete as single entities for customers. Such extended corporations reach out not only with business relationships; they must integrate their business processes and information systems. In this paper, we review the business and technological requirements of modern extended organizations and explain how adaptive business objects and controlled interoperability are the key enabling technologies to the challenge of integrated value chains. q 2000 Elsevier Science B.V. All rights reserved.

Scenarios of using web services in M-commerce

The web service paradigm is a promising technology for developing applications in open, distributed and heterogeneous environments. The proliferation of this new technology has coincided with significant advances in the hardware and software capabilities of mobile devices. Due to the great benefits that come with the web service technology, such as interoperability, dynamic service discovery and reusability, there is a strong interest in making mobile devices capable of providing and consuming web services over wireless networks. This paper describes several scenarios of using web services in mobile devices and identifies their advantages, issues and challenges.

Unified publication and discovery of semantic Web services

The challenge of publishing and discovering Web services has recently received lots of attention. Various solutions to this problem have been proposed which, apart from their offered advantages, suffer the following disadvantages: (i) most of them are syntactic-based, leading to poor precision and recall, (ii) they are not scalable to large numbers of services, and (iii) they are incompatible, thus yielding in cumbersome service publication and discovery. This article presents the principles, the functionality, and the design of PYRAMID-S which addresses these disadvantages by providing a scalable framework for unified publication and discovery of semantically enhanced services over heterogeneous registries. PYRAMID-S uses a hybrid peer-to-peer topology to organize Web service registries based on domains. In such a topology, each Registry retains its autonomy, meaning that it can use the publication and discovery mechanisms as well as the ontology of its choice. The viability of this approach is demonstrated through the implementation and experimental analysis of a prototype.

Developing scientific workflows from heterogeneous services

Scientific WorkFlows (SWFs) need to utilize components and applications in order to satisfy the requirements of specific workflow tasks. Technology trends in software development signify a move from component-based to service-oriented approach, therefore SWF will inevitably need appropriate tools to discover and integrate heterogeneous services. In this paper we present the SODIUM platform consisting of a set of languages and tools as well as related middleware, for the development and execution of scientific workflows composed of heterogeneous services.

PYRAMID-S: a scalable infrastructure for semantic Web service publication and discovery

Web services enhance current Web functionality by altering its nature from document to service-oriented. As the number of Web services increases, it becomes increasingly important to provide a scalable infrastructure of registries that allows both developers and end-users to perform discovery of semantic Web enabled services. The discovery of services needs to be based on QoS characteristics in order to enable result ranking and service selection. Current Web service publication and discovery mechanisms, such as UDDI, either address these issues partially or not at all. In this paper, we build on the enabling technologies of Web services, peer-to-peer and semantic Web in an attempt to address all these important dimensions of service publication and discovery. More specifically, we use a hybrid peer-to-peer topology to organize registries based on domains. In such a model, each registry retains its autonomy, meaning that it can use the publication and discovery mechanisms as well as the ontology of its choice.

Taxonomy of attacks and defense mechanisms in P2P reputation systems—Lessons for reputation system designers

A B S T R A C T Robust and credible reputation systems are essential for the functionality of Peer-to-Peer (P2P) applications. However, they themselves are susceptible to various types of attacks. Since most current efforts lack an exploration of a comprehensive adversary model, we try to fi ll in this gap by providing a thorough view of the various credibility threats against a decentralized reputation system and the respective defense mechanisms. Therefore, we explore and classify the types of potential attacks against reputation systems for P2P applications. We also study and classify the defense mechanisms which have been proposed for each type of attack and identify confl icts between defense mechanisms and/or desirable characteristics of credible reputations systems. We fi nally propose a roadmap for reputation system designers on how to use the results of our survey for the design of robust reputation systems for P2P applications. c

Interoperability among Heterogeneous Services

Service-oriented computing (SOC) has been marked as the technology trend which caters for the interoperability among the components of a distributed system. However, the emergence of various incompatible instantiations of the SOC paradigm e.g. Web, grid and P2P services, as well as the interoperability problems encountered within each of these instantiations (e.g. Web service interoperability problems addressed by the WS-I basic profile) state clearly that interoperability is still elusive. In order to address this problem we first need to identify all problem dimensions and consequently to provide appropriate solutions. Within this paper we describe a set of interoperability dimensions that need to be considered and we present a generic service model which we view as a first step in addressing some of the identified problem dimensions

Mobile Electronic Commerce: Emerging Issues

There are many definitions for Mobile Electronic Commerce (M-Commerce). We define M-Commerce as any type of transaction of an economic value having at least at one end a mobile terminal and thus using the mobile telecommunications network. The Wireless Application Protocol (WAP) plays an important role in m-commerce by optimizing Internet standards for the constraints of the wireless environment and thus bridging the gap between Internet and mobile world. Mobile Network Operators can play a major role in m-commerce by being strategically positioned between customers and content/service providers. In this paper we investigate the roles the operator can play in m-commerce and discuss respective problems and emerging issues.