An orchestrator for dynamic interconnection of software components

Composing and orchestrating software components is a fundamental concern in modern software engineering. This paper addresses the possibility of such orchestration being dynamic, in the sense that the structure of component's interconnection patterns can change at run-time. The envisaged approach extends previous work by the authors on the use of coalgebraic models for the specification of software connectors.POSI/ICHS/44304/200

A perspective on service orchestration

Service-oriented computing is an emerging paradigm with increasing impact on the way modern software systems are designed and developed. Services are autonomous, loosely coupled and heterogeneous computational entities able to cooperate to achieve common goals. This paper introduces a model for service orchestration, which combines a exogenous coordination model, with services’ interfaces annotated with behavioural patterns specified in a process algebra which is parametric on the interaction discipline. The coordination model is a variant of Reo for which a new semantic model is proposed

An approach to modelling and verification of component based systems

We build on a framework for modelling and investigating component-based systems that strictly separates the description of behavior of components from the way they interact. We discuss various properties of system behavior as liveness, local progress, local and global deadlock, and robustness. We present a criterion that ensures liveness and can be tested in polynomial time. © Springer-Verlag Berlin Heidelberg 2007

SAVCBS 2005 Proceedings: Specification and Verification of Component-Based Systems

This workshop is concerned with how formal (i.e., mathematical) techniques can be or should be used to establish a suitable foundation for the specification and verification of component-based systems. Component-based systems are a growing concern for the software engineering community. Specification and reasoning techniques are urgently needed to permit composition of systems from components. Component-based specification and verification is also vital for scaling advanced verification techniques such as extended static analysis and model checking to the size of real systems. The workshop will consider formalization of both functional and non-functional behavior, such as performance or reliability. This workshop brings together researchers and practitioners in the areas of component-based software and formal methods to address the open problems in modular specification and verification of systems composed from components. We are interested in bridging the gap between principles and practice. The intent of bringing participants together at the workshop is to help form a community-oriented understanding of the relevant research problems and help steer formal methods research in a direction that will address the problems of component-based systems. For example, researchers in formal methods have only recently begun to study principles of object-oriented software specification and verification, but do not yet have a good handle on how inheritance can be exploited in specification and verification. Other issues are also important in the practice of component-based systems, such as concurrency, mechanization and scalability, performance (time and space), reusability, and understandability. The aim is to brainstorm about these and related topics to understand both the problems involved and how formal techniques may be useful in solving them

Establishing Properties of Interaction Systems

We exhibit sufficient conditions for generic properties of component based systems. The model we use to describe component based systems is the formalism of interaction systems. Because the state space explosion problem is encountered in interaction systems (i.e., an exploration of the state space gets unfeasible for a large number of components), we follow the guideline that these conditions have to be checkable efficiently (i.e., in time polynomial in the number of components). Further, the conditions are designed in such a way that the information gathered is reusable if a condition is not satisfied. Concretely, we consider deadlock-freedom and progress in interaction systems. We state a sufficient condition for deadlock-freedom that is based on an architectural constraint: We define what it means for an interaction system to be tree-like, and we derive a sufficient condition for deadlock-freedom of such systems. Considering progress, we first present a characterization of this property. Then we state a sufficient condition for progress which is based on a directed graph. We combine this condition with the characterization to point out one possibility to proceed if the graph-criterion does not yield progress. Both sufficient conditions can be checked efficiently because they only require the investigation of certain subsystems. Finally, we consider the effect that failure of some parts of the system has on deadlock-freedom and progress. We define robustness of deadlock-freedom respectively progress under failure, and we explain how the sufficient conditions above have to be adapted in order to be also applicable in this new situation

Service-Interoperabilität für naturwissenschaftliche Anwendungen : Identifikation und Anpassung von komponentenbasierten Service-Mediatoren

In der Softwareentwicklung wird die Serviceorientierung als neues Realisierungsparadigma propagiert. Sie erlaubt lose gekoppelte Services bedarfsbezogen in Workflows zu aggregieren. Hierbei ist die Überbrückung der Heterogenität dieser Services ein anerkanntes Problem von hohem wirtschaftlichem Interesse. Es besteht der Bedarf die Service-Interoperabilität weitestgehend automatisch herzustellen. In dieser Arbeit wurde ein Konzept für Service-Mediatoren entwickelt, die über eine offene und erweiterbare, software-unterstützte Prozedur (semi-)automatisch identifiziert und problembezogen in einen Workflow eingebettet werden können. Service-Mediatoren über\-brücken die Heterogenität der einzelnen Services und erzielen so die geforderte Service-Interoperabilität. Die offene Architektur und Entwicklung dieser Prozedur erlaubt erstmals die Vorteile gängiger Ansätze zu integrieren. Um einmal entwickelte Service-Mediatoren in verschiedenen Workflows einsetzen und wiederverwenden zu können, bedarf es ihrer gezielten Identifikation und Anpassung. Leider stellt gerade die Suche nach benötigten Service-Mediatoren ein besonders schwieriges Problem da. Dies gilt insbesondere, wenn erst mehrere geeignet verknüpfte Service-Mediatoren zusammen die Service-Interoperabilität erreichen und bereits bei der Suche diese Kombination identifiziert werden muss. Die Aspekte der Suche und der Anpassung erfordern eine Beschreibungssprache, die die Fähig\-keiten eines Service-Mediators sowohl syntaktisch als auch semantisch beschreiben kann. Mit der Mediator Profile Language (MPL) wurde eine derartige, auf OWL basierende Beschreibungssprache entwickelt, die die Grundlage des entworfenen Komponentenmodells der Service-Mediatoren bildet. Sie erlaubt u. a. die Beschreibung der Komposition mehrerer Service-Mediatoren, sowie deren Konfiguration über zustandsbehaftete Eigenschaftsfelder. Die semantische Annotation eines Service-Mediators geschieht hierbei über Konzepte einer Domänenontologie. Im Rahmen dieser Arbeit wurden Matchmaking-Algorithmen zur Suche entwickelt, die eine Identifikation adäquater Service-Mediatoren und deren Komposition erlauben. Durch den Einsatz von Ontologien zur semantischen Annotation der Service-Mediatoren kann die Suche auch über rein syntaktische Merkmale hinaus durchgeführt werden. Trotz der den Servicebeschreibungen innewohnenden Unschärfe wurde ein Verfahren realisiert, welches die Servicebeschreibungen auf MPL abbildet und dabei eine automatische Annotation durch die Konzepte einer Ontologie vornimmt. Die Matchmaking-Algorithmen wurden auch auf das Problem der semantischen Suche nach Service-Operationen übertragen. Die entwickelten ontologiebasierten Matchmaking-Verfahren liefern im Vergleich zu Standard-IR-Techniken signifikant bessere Ergebnisse, wie durch entsprechende Benchmarks mit anschließender Messung von Precision und Recall gezeigt werden konnte.Service Interoperability for Science Applications - Identification and Adaptation of Component-Based Service MediatorsService-orientation is a new software paradigm for building distributed, component-based software. It allows the aggregation of loosely coupled services into value-added workflows. In this context the gap between heterogeneous services is an accepted problem with particular commercial interest. Thus, there is the need to create service interoperability semi-automatically. In this thesis the concept of service mediators is developed. Through a software-aided procedure service mediators are identified, adapted and integrated into workflows in order to bridge the heterogeneity of different services. Service mediators are software components realizing for instance transformation facilities. The open architecture of the developed procedure allows the integration of benefits from current approaches. The discovery of relevant service mediators is a difficult problem, especially if several service mediators have to be combined adequately to reach the desired service interoperability. One major challenge is that such compositions have to be identified during discovery. The discovery and adaptation phases of the software-aided procedure require a suitable description of the capabilities of service mediators. Such a description should contain both syntactical and semantical information. The OWL-based Mediator Profile Language (MPL) addresses these issues. MPL permits among other things the description of compositions of service mediators as well as their customization by stateful properties. Semantical information is assigned by concepts of a domain ontology. In this dissertation different matchmaking algorithms were developed supporting the user in identifying relevant service mediators as well as new compositions of service mediators. Requirements for service mediators are derived from service descriptions and represented by query profiles in MPL. Even though the service descriptions are fuzzy the query generation algorithm automatically creates semantical annotations by mapping syntactical information to concepts of the domain ontology. These annotations are also stored within the query profile. Due to the application of the domain ontology the discovery process enables not only syntactical matchmaking but also semantical matchmaking. Furthermore, the matchmaking algorithms were transferred to the problem of discovering service operations. By measuring precision and recall it could be shown that ontology-based matchmaking is advantageously over standard information retrieval techniques