George Athanasopoulos

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

Interoperability Among Heterogeneous Services: The Case of Integration of P2P Services with Web Services

Service-oriented computing (SOC) has been marked as the technology trend that caters for interoperability among the components of a distributed system. However, the emergence of various incompatible instantiations of the SOC paradigm, e.g. Web or peer-to-peer services (P2P), and the divergences encountered within each of these instantiations state clearly that interoperability is still an open issue, mainly due to its multi-dimensional nature. In this paper we address the interoperability problem by first presenting its multiple dimensions and then by describing a conceptual model called generic service model (GeSMO), which can be used as a basis for the development of languages, tools and mechanisms that support interoperability. We then illustrate how GeSMO has been utilized for the provision of a P2P service description language and a P2P invocation mechanism which leverages interoperability between heterogeneous P2P services and between P2P services and Web services.

Paving the Way for Interoperability in Digital Libraries: The DL.org Project

While Digital Libraries are working towards making universally accessible collections of human knowledge a reality, considerable advances are needed in Digital Libraries methodologies and technologies to make this happen. Achieving interoperability between Digital Libraries is a crucial requirement for reaching this goal. Interoperability is a multi-layered and context-specific concept. It encompasses different levels along a multidimensional spectrum ranging from organisational to technological aspects. Addressing the interoperability challenges is the prime goal of the DL.org project. DL.org is advancing the state of the art in this area, and is proposing solutions for interoperability in addition to best practices and shared standards, bringing together knowledge from the DELOS project and expertise of Digital Library stakeholders. To achieve its objectives, the project is looking at the DELOS Digital Library Reference Model and investigating interoperability from the viewpoint of the six fundamental Digital Library concepts: Content, User, Functionality, Quality, Policy, and Architecture. Our paper describes the results of DL.org research, and how the project is addressing the interoperability challenge from the perspectives of the six domains. Relevant Digital Library interoperability aspects will be described, from conceptualisation at a high organisational level to instantiation at process level, and modelling techniques for representing and enabling interoperability between heterogeneous digital library mediation approaches, methods, and systems. By pursuing the interoperability goal, DL.org is paving the way forward for embedding new research achievements into real-world systems, and is supporting the advancement of research and the creation of a European Information Space for the knowledge-based economy.

Semantically Enhanced Discovery of Heterogeneous Services

Industrial application development approaches are striving for solutions that promote the rapid development of flexible and adaptable systems and the exploitation of legacy systems and resources. The Service-oriented Development (SOD) paradigm, a current trend in software development, could be beneficial to industrial application development approaches. However, the heterogeneity in existing standards and protocols for the discovery of the various service types is an obstacle for the use of SOD in industry. This paper addresses this issue by proposing a solution that supports the unified discovery of heterogeneous services and thus supporting the use of SOD in industry. The proposed solution comprises a generic service model (GeSMO), which facilitates the specification of heterogeneous services, a query language called Unified Service Query Language (USQL), based on GeSMO, which facilitates the unified discovery of heterogeneous services within heterogeneous service registries and a query engine called USQL Engine, that enables the execution of queries described in terms of the USQL, upon heterogeneous service registries.

SAMBA — An Agent architecture for Ambient Intelligence Elements Interoperability

The SAMBA (Systems for AMBient intelligence enabled by Agents) architecture reported here is a conceptual service-oriented architecture supporting the interaction and interoperability of systems, applications and actors by the notion of an “Ambient Intelligence Element Society”. The objective is to provide an ecosystem infrastructure supporting the interaction and interoperability of various elements by encapsulating and representing them through agents acting as members of an Ambient Intelligence Elements Society, and by using executable models at run-time in support of interoperability.

Quantified matchmaking of heterogeneous services

As the service-oriented computing paradigm and its related technologies mature, it is expected that electronic services will continue to grow in numbers. In such a setting, the course of service discovery could yield many alternative yet heterogeneous services which, by all means, may be of different type and moreover distinguished by their quality characteristics. To come through such situations and ease the task of service selection, service search engines need to be powered by an efficient matchmaking mechanism, which will abstract requesters from service heterogeneity and provide them with the means for choosing the service that best fits their requirements, among a wide set of services with similar functionally. In this paper, we present an efficient service matchmaking algorithm, which facilitates the task of heterogeneous service selection, whilst combining and exploiting the syntactic, semantic, and Quality-of-Service (QoS) properties contained in service advertisements.

A functionality perspective on digital library interoperability

Digital Library (DL) interoperability requires addressing a variety of issues associated with functionality. We report on the analysis and solutions identified by the Functionality Working Group of the DL.org project during its deliberations on DL interoperability. Ultimately, we hope that work based on our perspective will lead to improved architectures and software, as well as to greater interoperability, for next-generation DL systems.

Platform Specific Extensions in the SOA-Pro Profile for the Description of Peer-to-Peer and Grid Services

Developments in service-oriented computing have led to the emergence of heterogeneous service technologies moving well beyond Web services, such as Peer-to-Peer (P2P) and Grid services. Although all these technologies instantiate the de-facto service-oriented model, they introduce a number of technology-specific characteristics which hinder their integration and interoperability. A first step in overcoming this obstacle is to address the aforementioned heterogeneity at the design level. In this paper, we present our work towards enriching the upcoming SOA-Pro profile, which supports the design of service-oriented systems in a platform-agnostic manner, with the concepts necessary to model P2P and Grid services. We propose a set of extensions, which capture the specific features of P2P and Grid services, as they are seen in two prominent representative platforms, namely the JXTA technology for P2P services, and the WSRF framework for Grid services. The applicability and merits of our contribution are demonstrated through a case study based on the Purchase Order example.