Christian Zirpins

Lifting XML Schema to OWL

The Semantic Web will allow software agents to understand and reason about data provided by Web applications. Unfortunately, formal ontologies, needed to express data semantics, are often not readily available. However, common data schemas can help to create ontologies. We propose mappings from XML Schema to OWL as well as XML to RDF and show how web engineering can benefit from the gained expressiveness as well as the use of inference services.

Flexible coordination of service interaction patterns

Service-oriented computing is meant to support loose relationships between organisations: Collaboration procedures on the application-level translate to interaction processes via Web Services. Service composition deals with the specification and enforcent of such processes. Its main focus is on service <i>orchestration</i> where workflow managent is utilised for proactive coordination. In such an approach, coordination process and interaction logic are usually captured in the same workflow - which leads to deficiencies in recognising the possible impact of operational coordination on the interaction logic. In this paper, we claim that the choice of coordination alternatives impacts the quality of the composed service and has to be customised to each specific service case. As a consequence, we outline a solution that is based on <i>service interaction patterns</i> where the paradigms of patterns and idioms are applied to interaction procedures and orchestration processes. This allows studying a) reusable interaction patterns typical for service relationships and b) for each pattern a range of possible coordination idioms. Finally, we sketch a technique that refines the service logic based on analysis of its interaction patterns and utilisation of suitable coordination idioms selected by rules in terms of changing service context.

Web service interfaces for inter-organisational business processes an infrastructure for automated reconciliation

For the majority of front-end e-business systems, the assumption of a coherent and homogeneous set of interfaces is highly unrealistic. Problems start in the back-end, with systems characterised by a heterogeneous mix of applications and business processes. Integration can be complex and expensive, as systems evolve more in accordance with business needs than with technical architectures. E-business systems are faced with the challenge to give a coherent image of a diversified reality. Web services make business interfaces more efficient, but effectiveness is a business requirement of at least comparable importance. We propose a technique for automatic reconciliation of the Web service interfaces involved in inter-organisational business processes. The working assumption is that the Web service front-end of each company is represented by a set of WSDL and WSCL interfaces. The result of our reconciliation method is a common interface that all the parties can effectively enforce. Indications are also given on ways to adapt individual interfaces to the common one. The technique was embodied in a prototype that we also present.

Advanced concepts for next generation portals

Over the last two years, portal sites surfaced as a major trend in electronic commerce. Unlike many other exaggerated trends, portals have become an important facet of the World Wide Web which is likely to stay. Emerging from search engines and catalogues, they integrate an increasing amount of information and functionality. The paper reflects on portal characteristics as well as on foundations of their realization and introduces technology needed for the next generation service trading concepts: based on the promising open source project Jetspeed, a prototype of the GIBRALTAR service portal is introduced, capable of integrating, trading and composing complex remote e-services.

The FRESCO framework: an overview

The dynamic composition of existing services into new services is at the core of service-oriented computing. The objective of FRESCO (Foundational Research on Service Composition) is to develop a framework that service providers can use in order to model, develop, and execute composite services. The FRESCO framework will include conceptual tools, such as models for service composition and aggregation. The framework will also include technology elements, such as an integrated development environment and specific components of the infrastructure for service execution. A methodology will be given for the use of the FRESCO framework in the development of composite service solutions. We describe the main aspects of the approach to service composition adopted in FRESCO.

Evolution of Service Processes by Rule Based Transformation

The notion of service is closely coupled with the notion of process in general and of workflow in particular. Processes capture the coordination logic for the various resources involved in the realisation of the service content. Moreover, processes drive the actual delivery of a service. Internal processes underpin the capabilities of a service provider. Delivery processes underpin contractual agreements between service providers and consumers. In both cases, the ability to adapt service processes in response to changing environmental conditions is fundamental. Change must be rapid but at the same time accurate and consistent. In this paper, we present the framework for automated process transformation developed within the context of the FRESCO (Foundational Research on Service Composition) initiative. The conceptual part of the framework builds on the standard workflow meta-model proposed by the WfMC (Workflow Management Coalition). The change logic is expressed by transformation rules that can be automatically applied to the processes underpinning a service. The technical part of the framework specifically targets Web service platforms and BPEL (Business Process Execution Language).

A Service Oriented Approach to Interorganisational Cooperation

Many E-business applications are based on increased cooperation between various organisational units and partners. System support for such applications can be provided using concepts from the area of service oriented computing — thus lifting inter-organisational integration to a higher level of effectiveness and efficiency. E-services provide means for modularisation of arbitrary organizational assets into components that can be dynamically offered, discovered, negotiated, accessed, and composed in an open application environment. Technically, E-services are software systems that are implemented on top of conventional information and communication technology. As an important step into that direction, Web Services have laid the foundation for interoperable communication between arbitrary systems. This paper introduces an approach to plan, build, and run such application-level services efficiently. Therefore, a fundamental notion of service, originating from distributed systems, is being extended by a specific concept of cooperative interaction processes. Accordingly, an application-level service model and corresponding service engineering mechanisms are proposed and realised as system software middleware based on OGSA Web Services and BPEL4WS processes.

Object orientation and web services

The annual European workshop on Object Orientation and Web Services focusses challenges and potentials of service-oriented computing in relation to object-oriented technologies and methodologies. In particular it brings together the academic and the industrial perspective on Web Services. This years issue was characterised by the competency and motivation of the participants, both workshop activists who presented their specific results as well as organisers and invited speaker, who contributed their broad experience. This report outlines the contributions and discussions of the event, as well as the conclusions reached by the participants.

A provision-centric model for electronic service

In addition to producing a pervasive standard and a technology framework, the Web service industry initiative has prompted businesses to re-examine their service delivery channels. Back-end systems are already in place to capture business knowledge and manage operational strategies and procedures. Web services enable access to such systems, as well as basic orchestration. The infrastructure is in place to recreate the business-level notion of an electronic service. However, the gap between technology-oriented and business-oriented models for services is still considerable. In this paper, we outline a model for electronic services as defined by the FRESCO project. The model constitutes an architectural blueprint of the technical and business infrastructure for an electronic service. The focus is on the provisional aspects of electronic services.

Generative Softwarekonstruktion auf Basis typisierter Komponenten

Die komponentenbasierte Entwicklungssicht erhalt zunehmend Aufmerksamkeit, insbesondere auf Grund der von ihr in Aussicht gestellten vielversprechenden Vorteile wie besserer Produktivitat, Test- und Wartbarkeit, Wiederverwendung und Qualitat. Andererseits fehlt immer noch ein solides Fundament, auf dem sich solche Erwartungen grunden konnen. Zumindest bildet jedoch ein kompositorisches Vorgehen zweifellos den Kern kompentenbasierter Entwicklung. Dieser Beitrag stellt daher einen als Generative Softwarekonstruktion bezeichneten Entwicklungsprozess vor, der auf Basis eines interaktionsorientierten Typmodells eine hochgradig automatisierte Komposition verteilter Anwendungssysteme erlaubt. Das semantisch reiche Typmodell wird dabei als Erweiterung des aktuellen CORBA Component Model vorgestellt, unterstutzt eine typkorrekte und bei Bedarf automatisch adaptierende Komposition und wird anhand seiner Anwendung in der Finananzdienstleistungsdomane illustriert.