14 research outputs found

    Development framework for web service choreographies in pervasive environments

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    Message correlation in web services choreographies: a 4-phase validation method

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    The majority of large companies are adopting Service Oriented Architectures, mainly to automate their business processes, both centralized and distributed. This paper will focus on distributed business processes. At the moment there are two interesting ways to implement a distributed business process, via orchestration or choreography. Whereas an orchestration can be thought of as a service composition with a single participant taking the lead, a choreography is a decentralized collaboration between different autonomous participants. One of the most prominent remaining issues, associated with both approaches, is the correlation problem, which is addressed in this paper. We will show that the abstract overall view, provided by a choreography description, makes it possible to determine (even at design time) whether its interactions can be unambiguously correlated. It is shown that this correlation validation is more feasible to realize in case of choreographies than with orchestrations, due to the orchestration's limited view on the overall business process

    IHE cross-enterprise document sharing for imaging: interoperability testing software

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    <p>Abstract</p> <p>Background</p> <p>With the deployments of Electronic Health Records (EHR), interoperability testing in healthcare is becoming crucial. EHR enables access to prior diagnostic information in order to assist in health decisions. It is a virtual system that results from the cooperation of several heterogeneous distributed systems. Interoperability between peers is therefore essential. Achieving interoperability requires various types of testing. Implementations need to be tested using software that simulates communication partners, and that provides test data and test plans.</p> <p>Results</p> <p>In this paper we describe a software that is used to test systems that are involved in sharing medical images within the EHR. Our software is used as part of the Integrating the Healthcare Enterprise (IHE) testing process to test the Cross Enterprise Document Sharing for imaging (XDS-I) integration profile. We describe its architecture and functionalities; we also expose the challenges encountered and discuss the elected design solutions.</p> <p>Conclusions</p> <p>EHR is being deployed in several countries. The EHR infrastructure will be continuously evolving to embrace advances in the information technology domain. Our software is built on a web framework to allow for an easy evolution with web technology. The testing software is publicly available; it can be used by system implementers to test their implementations. It can also be used by site integrators to verify and test the interoperability of systems, or by developers to understand specifications ambiguities, or to resolve implementations difficulties.</p

    Service-Oriented Middleware for the Future Internet: State of the Art and Research Directions

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    International audienceService-oriented computing is now acknowledged as a central paradigm for Internet computing, supported by tremendous research and technology development over the last ten years. However, the evolution of the Internet, and in particular, the latest Future Internet vision, challenges the paradigm. Indeed, service-oriented computing has to face the ultra large scale and heterogeneity of the Future Internet, which are orders of magnitude higher than those of today's service-oriented systems. This article aims at contributing to this objective by identifying the key research directions to be followed in light of the latest state of the art. This article more specifically focuses on research challenges for service-oriented middleware design, therefore investigating service description, discovery, access and composition in the Future Internet of services

    The CHORCH Approach: How to Model B2Bi Choreographies for Orchestration Execution

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    The establishment and implementation of cross-organizational business processes is an implication of today's market pressure for efficiency gains. In this context, Business-To-Business integration (B2Bi) focuses on the information integration aspects of business processes. A core task of B2Bi is providing adequate models that capture the message exchanges between integration partners. Following the terminology used in the SOA domain, such models will be called choreographies in the context of this work. Despite the enormous economic importance of B2Bi, existing choreography languages fall short of fulfilling all relevant requirements of B2Bi scenarios. Dedicated B2Bi choreography standards allow for inconsistent outcomes of basic interactions and do not provide unambiguous semantics for advanced interaction models. In contrast to this, more formal or technical choreography languages may provide unambiguous modeling semantics, but do not offer B2Bi domain concepts or an adequate level of abstraction. Defining valid and complete B2Bi choreography models becomes a challenging task in the face of these shortcomings. At the same time, invalid or underspecified choreography definitions are particularly costly considering the organizational setting of B2Bi scenarios. Models are not only needed to bridge the typical gap between business and IT, but also as negotiation means among the business users of the integration partners on the one hand and among the IT experts of the integration partners on the other. Misunderstandings between any two negotiation partners potentially affect the agreements between all other negotiation partners. The CHORCH approach offers tailored support for B2Bi by combining the strengths of both dedicated B2Bi standards and formal rigor. As choreography specification format, the ebXML Business Process Specification Schema (ebBP) standard is used. ebBP provides dedicated B2Bi domain concepts such as so-called BusinessTransactions (BTs) that abstractly specify the exchange of a request business document and an optional response business document. In addition, ebBP provides a format for specifying the sequence of BT executions for capturing complex interaction scenarios. CHORCH improves the offering of ebBP in several ways. Firstly, the execution model of BTs which allows for inconsistent outcomes among the integration partners is redefined such that only consistent outcomes are possible. Secondly, two binary choreography styles are defined as B2Bi implementation contract format in order to streamline implementation projects. Both choreography styles are formalized and provided with a formal execution semantics for ensuring unambiguity. In addition, validity criteria are defined that ensure implementability using BPEL-based orchestrations. Thirdly, the analysis of the synchronization dependencies of complex B2Bi scenarios is supported by means of a multi-party choreography style combined with an analysis framework. This choreography style also is formalized and standard state machine semantics are reused in order to ensure unambiguity. Moreover, validity criteria are defined that allow for analyzing corresponding models for typical multi-party choreography issues. Altogether, CHORCH provides choreography styles that are B2Bi adequate, simple, unambiguous, and implementable. The choreography styles are B2Bi adequate in providing B2Bi domain concepts, in abstracting from low-level implementation details and in covering the majority of real-world B2Bi scenarios. Simplicity is fostered by using state machines as underlying specification paradigm. This allows for thinking in the states of a B2Bi scenario and for simple control flow structures. Unambiguity is provided by formal execution semantics whereas implementability (for the binary choreography styles) is ensured by providing mapping rules to BPEL-based implementations. The validation of CHORCH's choreography styles is performed in a twofold way. Firstly, the implementation of the binary choreography styles based on Web Services and BPEL technology is demonstrated which proves implementability using relatively low-cost technologies. Moreover, the analysis algorithms for the multi-party choreography styles are validated using a Java-based prototype. Secondly, an abstract visualization of the choreography styles based on BPMN is provided that abstracts from the technicalities of the ebBP standard. This proves the amenability of CHORCH to development methods that start out with visual models. CHORCH defines how to use BPMN choreographies for the purpose of B2Bi choreography modeling and translates the formal rules for choreography validity into simple composition rules that demonstrate valid ways of connecting the respective modeling constructs. In summary, CHORCH allows integration partners to start out with a high-level visual model of their interactions in BPMN that identifies the types and sequences of the BusinessTransactions to be used. For multi-party choreographies, a framework for analyzing synchronization dependencies then is available. For binary choreographies, an ebBP refinement can be derived that fills in the technical parameters that are needed for deriving the implementation. Finally, Web Services and BPEL based implementations can be generated. Thus, CHORCH allows for stepwise closing the semantic gap between the information perspective of business process models and the corresponding implementations. It is noteworthy that CHORCH uses international standards throughout all relevant layers, i.e., BPMN, ebBP, Web Services and BPEL, which helps in bridging the heterogeneous IT landscapes of B2Bi partners. In addition, the adoption of core CHORCH deliverables as international standards of the RosettaNet community give testament to the practical relevance and promise dissemination throughout the B2Bi community.BetriebsĂŒbergreifende GeschĂ€ftsprozessintegration ist eine logische Konsequenz allgegenwĂ€rtigen Wettbewerbsdrucks. In diesem Kontext fokussiert Business-To-Business integration (B2Bi) auf die Informationsaustausche zwischen Unternehmen. Eine B2Bi-Kernanforderung ist die Bereitstellung adĂ€quater Modelle zur Spezifikation der Nachrichtenaustausche zwischen Integrationspartnern. Diese werden im Rahmen dieser Arbeit in Anlehnung an Service-orientierte Architekturen (SOA)-Terminologie Choreographien genannt. Bestehende Choreographiesprachen decken die Anforderungen an B2Bi-Choreographien nicht vollstĂ€ndig ab. Dedizierte B2Bi-Choreographiestandards definieren inkonsistente Austauschprozeduren fĂŒr grundlegende Interaktionen und nur unvollstĂ€ndige Semantiken fĂŒr fortgeschrittene Interaktionen. Formale oder Technik-getriebene Choreographiesprachen bieten die benötigte PrĂ€zision, lassen aber DomĂ€nenkonzepte vermissen oder operieren auf einer niedrigen Abstraktionsebene. Angesichts solcher MĂ€ngel wird die Spezifikation valider und vollstĂ€ndiger B2Bi-Choreographien zu einer echten Herausforderung. Gleichzeitig sind mangelhafte Choreographiemodelle gerade im B2Bi-Bereich besonders problematisch, da diese nicht nur zwischen Fach- und IT-Abteilung, sondern auch ĂŒber Unternehmensgrenzen hinweg eingesetzt werden. Der CHORCH-Ansatz schafft an dieser Stelle mittels maßgeschneiderter Choreographien Abhilfe, welche die Vorteile von B2Bi-Choreographien und von formalen AnsĂ€tzen kombinieren. Als Ausgangspunkt wird das ebXML Business Process Specification Schema (ebBP) verwendet, das als B2Bi-Choreographiestandard DomĂ€nenkonzepte wie zum Beispiel sogenannte BusinessTransactions (BTs) bietet. Eine BT ist der Basisbaustein von B2Bi-Choreographien und spezifiziert den Austausch eines GeschĂ€ftsdokuments sowie eines optionalen Antwortdokuments. DarĂŒber hinaus bietet ebBP ein Format zur Spezifikation von BT-Kompositionen zur UnterstĂŒtzung komplexer Interaktionen. CHORCH erweitert ebBP wie folgt. Erstens, das AusfĂŒhrungsmodell fĂŒr BTs wird neu definiert, um inkonsistente ErgebniszustĂ€nde zu eliminieren. Zweitens, fĂŒr Entwicklungsprojekte werden zwei binĂ€re Choreographieklassen definiert, die als B2Bi-Implementierungskontrakt dienen sollen. Die Formalisierung beider Klassen sowie formale operationale Semantiken gewĂ€hrleisten Eindeutigkeit, wĂ€hrend ValiditĂ€tskriterien die AusfĂŒhrbarkeit entsprechender Modelle mittels BPEL-basierter Orchestrationen garantieren. Drittens, zur Analyse der Synchronisationsbeziehungen komplexer B2Bi-Szenarien wird eine Multi-Party-Choreographieklasse nebst Analyseframework definiert. Wiederum wird fĂŒr diese Klasse eine Formalisierung definiert, die mittels Standard-Zustandsautomatensemantik Eindeutigkeit gewĂ€hrleistet. Ferner garantieren ValiditĂ€tskriterien die Anwendbarkeit der definierten Analysealgorithmen. Insgesamt bieten die Choreographieklassen des CHORCH-Ansatzes ein B2Bi-adĂ€quates, einfaches, eindeutiges und implementierbares Modell der Nachrichtenaustausche zwischen B2Bi-Partnern. B2Bi-AdĂ€quatheit wird durch Verwendung von B2Bi-DomĂ€nenkonzepten, Abstraktion von rein technischen Kommunikationsdetails und Abdeckung der meisten praktisch relevanten B2Bi-Szenarien gewĂ€hrleistet. Einfachheit ist ein Ausfluss der Verwendung eines Zustandsmaschinen-basierten Modellierungsparadigmas, das die Definition des Interaktionsfortschritts in Form von ZustĂ€nden sowie einfache Kontrollflussstrukturen ermöglicht. Eindeutigkeit wird durch die Verwendung formaler Semantiken garantiert, wĂ€hrend Implementierbarkeit (fĂŒr die beiden binĂ€ren Choreographieklassen) durch Angabe von Mapping-Regeln auf BPEL-Orchestrationen sichergestellt wird. Die Validierung der CHORCH-Choreographieklassen erfolgt in zweierlei Hinsicht. Erstens, die Implementierbarkeit der binĂ€ren Choreographieklassen mit Hilfe von Web Services und BPEL wird durch die Definition entsprechender Mappingregeln belegt. Weiterhin wird das Analyseframework der Multi-Party-Choreographieklasse als Java-Prototyp implementiert. Zweitens, fĂŒr alle Choreographieklassen wird eine abstrakte Visualisierung auf BPMN-Basis definiert, die von diversen technischen Parametern des ebBP-Formats abstrahiert. Damit wird die Integrierbarkeit der CHORCH-Choreographieklassen in EntwicklungsansĂ€tze, die ein visuelles Modell als Ausgangspunkt vorsehen, belegt. CHORCH definiert, wie sogenannte BPMN-Choreographien zum Zweck der B2Bi-Choreographiemodellierung zu verwenden sind und ĂŒbersetzt die ValiditĂ€tskriterien der CHORCH-Choreographieklassen in einfache Modell-Kompositionsregeln. In seiner Gesamtheit bietet CHORCH somit einen Ansatz, mit Hilfe dessen B2Bi-Partner zunĂ€chst die Typen und zulĂ€ssigen Reihenfolgen ihrer GeschĂ€ftsdokumentaustausche auf Basis eines abstrakten visuellen BPMN-Modells identifizieren können. Im Fall von Multi-Party-Choreographien steht dann ein Framework zur Analyse der Synchronisationsbeziehungen zwischen den Integrationspartnern zur VerfĂŒgung. Im Fall von binĂ€ren Choreographien können ebBP-Verfeinerungen abgeleitet werden, welche die Modelle um technische Parameter anreichern, die zur Ableitung einer Implementierung benötigt werden. Diese ebBP-Modelle sind in Web Services- und BPEL-basierte Implementierungen ĂŒbersetzbar. Damit erlaubt CHORCH die schrittweise ÜberbrĂŒckung der semantischen LĂŒcke zwischen der Informationsaustauschperspektive von GeschĂ€ftsprozessmodellen und den zugehörigen Implementierungen. Ein beachtenswerter Aspekt des CHORCH-Ansatzes ist die Verwendung einschlĂ€giger internationaler Standards auf allen Abstraktionsebenen, im Einzelnen BPMN, ebBP, Web Services und BPEL. Die Verwendung von Standards trĂ€gt dem heterogenen Umfeld von B2Bi-Szenarien Rechnung. ZusĂ€tzlich wurden Kernergebnisse des CHORCH-Ansatzes als internationale Standards der RosettaNet-B2Bi-Community veröffentlicht. Dies belegt die praktische Relevanz des Ansatzes und fördert die Verbreitung innerhalb der B2Bi-Community

    Web service choreography conformance verification through the piX-model

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    As the adoption of the Service Oriented Architecture paradigm has dramatically increased over the past few years, proper coordination of loosely coupled services becomes an important issue when building state-of-the-art applications. This coordination is typically organized through orchestration (requiring a central coordinating entity) or through choreographies. While the latter approach allows for a fully distributed coordination, the need also arises for a distributed conformance check, ensuring that each participant of the choreography behaves according to the general choreography. In this paper, a formalism is presented to ensure this conformance at design time, with possible extensions to deploy time and to runtime conformance checking. This formalism is referred to as the piX-model and it will be shown that the approach taken is inherently less complex, both in time and space, than the conventional p-calculus-based approach, whilst offering the same conformance guarantees. This gain in performance allows for a small design turnaround time, and also opens the avenue to runtime conformance checking by resource constrained devices

    Intermedial Studies

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    Intermedial Studies provides a concise, hands-on introduction to the analysis of a broad array of texts from a variety of media – including literature, film, music, performance, news and videogames, addressing fiction and non-fiction, mass media and social media. The detailed introduction offers a short history of the field and outlines the main theoretical approaches to the field. Part I explains the approach, examining and exemplifying the dimensions that construct every media product. The following sections offer practical examples and case studies using many examples, which will be familiar to students, from Sherlock Holmes and football, to news, vlogs and videogames. This book is the only textbook taking both a theoretical and practical approach to intermedial studies. The book will be of use to students from a variety of disciplines looking at any form of adaptation, from comparative literature to film adaptations, fan fictions and spoken performances. The book equips students with the language and understanding to confidently and competently apply their own intermedial analysis to any text
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