Dominik Kuropka

Semantic Service Provisioning

Service-oriented computing has recently gained extensive momentum in both industry and academia, and major software vendors hook on to the service paradigm and tailor their software systems towards services in order to accommodate ever-changing process and product requirements in todays dynamic market environments. While dynamic binding of services at runtime was identified as a core functionality of service-based environments as far back as 2000, its industrial-strength implementation has yet to be achieved. The main reason for this is the lack of rich service specifications, concepts, and tools to process them. This book introduces advanced concepts in service provisioning and service engineering, including semantic concepts, dynamic discovery and composition, and illustrates them in a concrete business use case scenario. To prove the validity of the concepts and technologies, a semantic service provisioning reference architecture framework as well as a prototypical implementation of its subsystems and a prototypical realization of a proper business scenario are presented. Thus the book goes way beyond current service-based software technologies by providing a coherent and consistent set of technologies and systems functionality that realizes advanced concepts in service provisioning. Both the use case scenario and the provisioning platform have already been substantiated and implemented by the EU-funded Adaptive Services Grid project. The book therefore presents state-of-the-art research results that have already passed a real industrial implementation evaluation which is based on the work of over 20 European partners cooperating in the field of semantic service provisioning.

Implementing a Semantic Service Provision Platform

ZusammenfassungDie nahtlose Integration von Informationssystemen spielt eine wichtige Rolle bei der Entwicklung und Wartung von Softwareprodukten. In den heutigen, dynamischen Märkten ist Veränderung eher die Regel als die Ausnahme. Daher ist die Möglichkeit, Softwareprodukte effizient an Veränderungen der Anwendungslandschaft anzupassen, ein wichtiger Vorteil für eine Unternehmung. Die Vision dienstorientierter Ansätze geht dahin, dass unternehmensrelevante Funktionalitäten von existierenden Softwaresystemen als Dienste bereitgestellt werden, die dann durch eine Komposition der Dienste zu weiteren oder neuen Anwendungen zusammengestellt werden. Leider ist diese Vision bis heute noch nicht in einem hinreichenden Maß in der Praxis umgesetzt worden. Der Artikel präsentiert eine Plattform, die eine semantische Suche, Komposition und Ausführung von Diensten unterstützt und die oben genannte Vision umsetzt. Die Realisierung der Vision wurde prototypisch für ein begrenztes Anwendungsszenario umgesetzt, um ihre grundsätzliche Implementierbarkeit aufzuzeigen. Erkenntnisse aus der prototypischen Umsetzung sind: Erstens, die Anforderungen an die logischen Reasoner sind hoch, wenn man „echte“ Problemstellungen lösen möchte. Zweitens, die formale Spezifikation „realer“ Dienste ist eine aufwändige Aufgabe und drittens, es ist zurzeit nicht einfach, reale Szenarien für eine dynamische Dienstkomposition zu finden, weil das Vertrauen in diese Technologie fehlt, weil die Frage nach der Verantwortung im Fehlerfalle nicht geklärt ist und weil die Investitionen in die semantische Modellierung von Diensten sich nur für hochdynamische Umgebungen auszahlen.AbstractSeamless integration of information systems plays a key role in the development and maintenance of products. In today’s dynamic market environments, change is the rule rather than the exception. Consequently, the ability to change products is an effective way to adapt to a changing information technology landscape which is an important competitive advantage of a successful company. The vision of service-oriented computing is to capture business relevant functionalities of existing software systems as services and use service composition to form composite applications. Unfortunately, this vision has yet to be achieved. We present here a high-level overview of a semantic service discovery, composition, and enactment system that realizes this vision. Rather than addressing a fully fledged industrial strength system, we present a research prototype that realizes this vision in a narrow application domain to show the general feasibility of automatic semantic discovery, composition and flexible enactment of services. The lessons we learned from implementing this prototype are: a) The requirements regarding the features of logical reasoners for the implementation of “real” scenarios are high. b) A formal and exact specification of the semantics of “real world” services is a laborious task. c) It is hard to find adequate scenarios, because people don’t trust this technology and they don’t like to give the control on business processes to a machine, because questions like “Who is responsible?” arise. Furthermore, the application of automated and flexible service discovery and composition at run-time is only cost-effective if changes and volatilities are frequent in the service landscape.

Semantic Enterprise Services Platform: Motivation, Potential, Functionality and Application Scenarios

Service oriented software architectures will form the core of operational enterprise IT landscapes in the future. This contribution starts with an introduction of the state of the art in service oriented architectures. A concrete case study identifies central requirements that are not satisfied by these architectures so far. The authors argue that semantically rich descriptions of services are essential to tap the full potential of service oriented architectures in enterprise environments. This regards matchmaking and binding of services, integration of new services as well as the cost-efficient development of added value services by composing semantically described basic services. This paper introduces a semantic service platform that implements dynamic matchmaking, composition and binding of semantically described services. Finally its functionality and possible application scenarios are outlined

Objektorientierter Entwurf eines flexiblen Workflow-Management-Systems

Zusammenfassung. Dieser Beitrag enthält die wesentlichen konzeptionellen Überlegungen zur Entwicklung eines flexiblen Workflow-Management-Systems. Ausgehend von einer Diskussion möglicher Modellierungsalternativen wird unter Verwendung objektorientierter Modellierungstechniken ein Workflow-Meta-Schema entwickelt, das die relevanten Entitäten klassifiziert und ihre Beziehungen abbildet. Anhand eines Beispiels werden die getroffenen Entwurfentscheidungen ausführlich begründet. Schließlich werden Zustände und Zustandsübergänge von Workflow-Instanzen beschrieben, und es wird diskutiert, wie dynamische Veränderungen von Workflows zur Laufzeit durchgeführt werden können, um laufende Workflows dynamisch an veränderte Umweltbedingungen anzupassen.Abstract. This contribution discusses the conceptual design of a flexible workflow management system. After discussing a set of modeling alternatives, a workflow meta schema is developed, using object oriented design principles. We describe how workflows are modelled and executed. Key design decisions are validated using a sample workflow model and a sample workflow instance based on that model. We propose a state transition diagram for workflow instances, and we discuss how dynamic modifications of workflow models can be conducted to adapt running workflow instances to changes in the workflow environment.

Requirements for automated service composition

Automated service composition is an important approach to create aggregate services out of existing services. Several different approaches towards automated service composition exist. They differ not only in the used algorithms but also in provided functionality. While some support the creation of compositions with alternative or parallel control flow, others are missing this functionality. This diversity yields from a missing consensus on the required functionality to automatically compose real-world services. Hence, with this paper we aim at providing the foundation for such a consensus. We derived the required functionality from multiple business scenarios set up in the Adaptive Services Grid (ASG) project.

Core Concepts and Use Case Scenario

This chapter starts the discussion on semantic service provision by establishing a common terminology. Furthermore, we are introducing a non-trivial use case scenario, which acts as a base for the following explanations in the book. Based on both the terminology and the use case, this chapter defines the semantic service provision lifecycle based on the introduced core building blocks.

Software Development Dynamics: Current Trends and Future Developments

In a digital networked economy companies rely increasingly on software systems to collaborate with partner companies, to provide services to their customers and overall to achieve their business goals. While this trend has been around for years, it continues to have implications on the way software systems are designed and developed, as well as on the business models companies are based on. On the other hand, software technology provides new opportunities for companies and new methods of doing business. This paper investigates the relationship between recent achievements in software, information systems, and process technology on the one hand and the new opportunities facilitated by these technologies on the other. To provide one step forward towards understanding this relationship, this paper discusses recent trends and technologies in software, information systems and process technology. Rather than focusing on the technical details of these domains, the fundamental concepts and the new opportunities are discussed.

Workflows in Computation Grids

This paper shows that flexibility of workflow executions, i.e., the ability to deviate from a given model on the fly and during execution, is crucial for a wide applicability of workflow management technology in computing grids. Since flexibility concepts for workflows have been elaborated extensively in conventional business-oriented domains, we show how to reuse and adapt them for workflow management in computation grids

Application and Outlook

Even though semantic service provisioning is still a hot research topic, many projects and collaborations already gained a tremendous amount of experiences. This chapter sketches the prototype experiences from one of these projects, the European integration project ASG, which was also the starting point for this book. The chapter further discusses possible next steps for advanced service provisioning platforms.

Workshop PC chairs' message

The rise of service-oriented architectures will boost the amount of available Web services in the future. This will put the question of proper Web service discovery and description on the agenda. Current technologies such as UDDI and ongoing research efforts on semantic service technology are usually focused on technical, theoretical and correctness issues rather than on the ease of use. This results in high requirements on both the service requesters who are searching for services, and the service providers who have to contribute proper descriptions of their services.