nach oben

2009 | Buch

Kapitel lesen Erstes Kapitel lesen

Distributed Applications and Interoperable Systems

9th IFIP WG 6.1 International Conference, DAIS 2009, Lisbon, Portugal, June 9-11, 2009. Proceedings

herausgegeben von: Twittie Senivongse, Rui Oliveira

Verlag: Springer Berlin Heidelberg

Buchreihe : Lecture Notes in Computer Science

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

Einloggen, um Zugang zu erhalten

Über dieses Buch

This book constitutes the refereed proceedings of the 9th IFIP WG 6.1 International Conference on Distributed Applications and Interoperable Systems, DAIS 2009, held in Lisbon, Portugal, in June 2009. The DAIS conference was held as part of the federated event on Distributed Computing Techniques (DisCoTec), together with the 11th International Conference on Coordination Models and Languages (Coordination 2009) and the IFIP WG 6.1 International Conference on Formal Techniques for Distributed Systems (FMOODS/FORTE 2009). The 12 revised full papers presented were carefully reviewed and selected from 32 submissions. The papers address service orientation, quality of service and service contract, business processes, Web services, service components, algorithms and protocols supporting dependability, fault tolerance, data replication, group communication, adaptive and collaborative systems, context awareness, model-driven development, middleware for ubiquitous computing and sensor networks, ad hoc network protocols, peer-to-peer systems, and overlays. They are organized in topical sections peer-to-peer networks, adhoc networks, dependability, and infrastructure and services.

Inhaltsverzeichnis

Frontmatter

Peer-to-Peer Networks

Exploiting Synergies between Coexisting Overlays

Abstract

Overlay networks have emerged as a powerful paradigm to realise a large range of distributed services. However, as the number of overlays grows and the systems that use them become more interconnected, overlays must increasingly co-exist within the same infrastructure. When this happens, overlays have to compete for limited resources, which causes negative interferences. This paper takes an opposite view, and argues that coexisting overlays may also introduce positive synergies that can be exploited to benefit a distributed system. Unfortunately, and in spite of some pioneering work, this phenomenon is still poorly understood and has yet to be investigated systematically. To address this problem, this paper proposes a principled classification of synergies, and illustrates how it can be used to exploit synergies in a typical overlay platform targeting gossip protocols (GossipKit). We review in detail the risks and benefits of each identified synergy; we present experimental data that validate their added value, and finally discuss the lessons we have learnt from our implementation.

Shen Lin, François Taïani, Gordon Blair

D-Praxis : A Peer-to-Peer Collaborative Model Editing Framework

Abstract

Large-scale industrial systems involve nowadays hundreds of developers working on hundreds of models representing parts of the whole system specification. Unfortunately, few tool support is provided for managing this huge set of models. In such a context of collaborative work, the approach commonly adopted by the industry is to use a central repository and to make use of merge mechanisms and locks.

In this article we present a collaborative model editing framework, peer-to-peer oriented, that considers that every developer has his own partial replication of the system specification and that makes use of messages exchange for propagating changes made by developers. Our approach has the advantage not to be based on a single repository, which is more and more the case in large-scale industrial projects.

Alix Mougenot, Xavier Blanc, Marie-Pierre Gervais

A Reflective Middleware to Support Peer-to-Peer Overlay Adaptation

Abstract

As peer-to-peer systems are evolving from simplistic application specific overlays to middleware platforms hosting a range of potential applications it has become evident that increasingly configurable approaches are required to ensure appropriate overlay support is provided for divergent applications. This is exacerbated by the increasing heterogeneity of networked devices expected to host the overlay. Traditional adaptation approaches rely on simplistic design-time isolated fine-tuning of overlay operations. This, however, cannot fully support the level of configurability required by next generation peer-to-peer systems. To remedy this, a middleware overlay framework is designed that promotes the use of architectural reconfiguration for adaptive purposes. Underpinning this is a generic reusable component pattern that utilises software reflection to enable rich and extensible adaptation of overlays beneath divergent applications operating in heterogeneous environments. This is evaluated through a number of case-study experiments showing how overlays developed using the framework have been adapted to address a range of application and environmental variations.

Gareth Tyson, Paul Grace, Andreas Mauthe, Gordon Blair, Sebastian Kaune

Adhoc Networks

WiSeKit: A Distributed Middleware to Support Application-Level Adaptation in Sensor Networks

Abstract

Applications for Wireless Sensor Networks (WSNs) are being spread to areas in which the contextual parameters modeling the environment are changing over the application lifespan. Whereas software adaptation has been identified as an effective approach for addressing context-aware applications, the existing work on WSNs fails to support context-awareness and mostly focuses on developing techniques to reprogram the whole sensor node rather than reconfiguring a particular portion of the sensor application software. Therefore, enabling adaptivity in the higher layers of a WSN architecture such as the middleware and application layers, beside the consideration in the lower layers, becomes of high importance. In this paper, we propose a distributed component-based middleware approach, named WiSeKit, to enable adaptation and reconfiguration of WSN applications. In particular, this proposal aims at providing an abstraction to facilitate development of adaptive WSN applications. As resource availability is the main concern of WSNs, the preliminary evaluation shows that our middleware approach promises a lightweight, fine-grained and communication-efficient model of application adaptation with a very limited memory and energy overhead.

Amirhosein Taherkordi, Quan Le-Trung, Romain Rouvoy, Frank Eliassen

Automated Assessment of Aggregate Query Imprecision in Dynamic Environments

Abstract

Queries are widely used for acquiring data distributed in opportunistically formed mobile networks. However, when queries are executed in such dynamic settings, the returned result may not be consistent, i.e., it may not accurately reflect the state of the environment. It can thus be difficult to reason about the meaning of a query’s result. Reasoning about imperfections in the result becomes even more complex when in-network aggregation is employed, since only a single aggregate value is returned. We define the semantics of aggregate queries in terms of a qualitative description of consistency and a quantitative measure of imprecision. We provide a protocol that performs in-network aggregation while simultaneously generating quality assessments for the query result. The protocol enables intuitive interpretations of the semantics associated with an aggregate query’s execution in a dynamic environment.

Vasanth Rajamani, Christine Julien, Jamie Payton

Dependability

Fault-Tolerant Aggregation by Flow Updating

Abstract

Data aggregation plays an important role in the design of scalable systems, allowing the determination of meaningful system-wide properties to direct the execution of distributed applications. In the particular case of wireless sensor networks, data collection is often only practicable if aggregation is performed. Several aggregation algorithms have been proposed in the last few years, exhibiting different properties in terms of accuracy, speed and communication tradeoffs. Nonetheless, existing approaches are found lacking in terms of fault tolerance. In this paper, we introduce a novel fault-tolerant averaging based data aggregation algorithm. It tolerates substantial message loss (link failures), while competing algorithms in the same class can be affected by a single lost message. The algorithm is based on manipulating flows (in the graph theoretical sense), that are updated using idempotent messages, providing it with unique robustness capabilities. Furthermore, evaluation results obtained by comparing it with other averaging approaches have revealed that it outperforms them in terms of time and message complexity.

Paulo Jesus, Carlos Baquero, Paulo Sérgio Almeida

Foraging for Better Deployment of Replicated Service Components

Abstract

Our work focuses on distributed software services and their requirements in terms of system performance and dependability. We target the problem of finding optimal deployment mappings involving multiple services, i.e. mapping service components in the software architecture to the underlying platforms for best possible execution. We capture important non-functional requirements of distributed services, regarding performance and dependability. These models are then used to construct appropriate cost functions that will guide our heuristic optimization method to provide better deployment mappings for service components. This paper mainly focuses on dependability. In particular, a logic enabling replication management and deployment for increased dependability is presented. To demonstrate the feasibility of our approach, we model a scenario with 15 services each with different redundancy levels deployed over a 10-node network. We show by simulation how the deployment logic proposed is capable to satisfy replica deployment requirements.

Máté J. Csorba, Hein Meling, Poul E. Heegaard, Peter Herrmann

A Generic Group Communication Approach for Hybrid Distributed Systems

Abstract

Group Communication is a powerful abstraction that is being widely used to manage consistency problems in a variety of distributed system models, ranging from synchronous, to time-free asynchronous model. Though similar in principles, distinct implementation mechanisms have been employed in the design of group communication for distinct system models. However, the hybrid nature of many modern distributed systems, with dynamic and varied QoS guarantees, has put forward the need for integrated models. Furthermore, adaptation with degraded service is a common requirement in such scenarios. This paper tackles this new challenge by introducing a generic group communication mechanism. Because of its integrated feature, our approach is capable of handling group communication for both synchronous and asynchronous distributed systems, dynamically adapting to the available QoS. For example, it can dynamically switch to the asynchronous version when the run-time system can no longer guarantee a timely operation. The properties and algorithms of the integrated approach are presented in this paper, as well as a performance evaluation through simulation, comparing this mechanism with some classical approaches.

Raimundo José de Araújo Macêdo, Allan Edgard Silva Freitas

Infrastructure and Services

A Flexible Approach for Business Processes Monitoring

Abstract

Business processes and their implementation as Web Service Compositions are not only dependent on Web Services and partners all over the Internet, but also on their failsafe execution. Service providers have to obligate their services to perform according to negotiated Quality of Service (QoS) parameters. For example, response time and throughput are important parameters to achieve fast and efficient services. Overloaded or failing services may compromise the reliability and execution of whole enterprise processes.

In this paper we introduce a flexible monitoring approach for the measurement of QoS in BPEL (Business Process Execution Language) processes. We propose a generic algorithm for QoS aggregation in BPEL processes. The novel generic aggregation algorithm applies customized aggregation functions for QoS dimensions. Furthermore, we present a BPEL monitoring system which supports ad-hoc sensor deployment and efficient runtime and offline data aggregation not only for whole process descriptions but also sections inside service processes.

Diana Comes, Steffen Bleul, Thomas Weise, Kurt Geihs

Distributed Contracting and Monitoring in the Internet of Services

Abstract

The recent approval of the EU Services Directive is fostering the Internet of Services (IoS) and will promote the emergence of marketplaces for business and real-world services. From a research perspective, the IoS will require a new bread of technological infrastructures to support the concepts of business service description, contract management from various perspectives, end-to-end marketplaces, and business monitoring.

The IoS is a vision referring to web service-based digital societies. When service hosting moves from best-effort provisioning to guaranteed service delivery, monitoring becomes a crucial point of proof for providers and consumers of such services. We present the uplifting of technical contract monitoring results to business effects based on the distributed service infrastructure developed in project THESEUS, use case TEXO.

Josef Spillner, Matthias Winkler, Sandro Reichert, Jorge Cardoso, Alexander Schill

Dependency Management in Smart Homes

Abstract

In future smart homes functionality will be provided to the inhabitants by software services decoupled from the underlying hardware devices. While this will enhance flexibility and will allow to provide cross-functionalities across multiple devices it will also lead to resource conflicts. Future devices will provide basic functionalities which are used by separate higher level services. Each person will use a number of different services and each environment can be inhabited by multiple users at the same time. All respective services have to be executed based on a limited number of devices, which will result in resource conflicts. In this paper we describe how we extended our existing dependency management approach for smart home services with a mechanism for monitoring service bindings and handling access control based on priority groups.

Daniel Retkowitz, Sven Kulle

SoundPark: Towards Highly Collaborative Game Support in a Ubiquitous Computing Architecture

Abstract

Ubiquitous computing architectures enable interaction and collaboration in multi-user applications. We explore the challenges of integrating the disparate services required in such architectures and describe how we have met these challenges in the context of a real-world application that operates on heterogeneous hardware and run-time environments. As a compelling example, we consider the role of ubiquitous computing to support the needs of a distributed multi-user game, including mobility, mutual awareness, and geo-localization. The game presented here, “SoundPark”, is played in a mixed-reality environment, in which the physical space is augmented with computer-generated audio and graphical content, and the players communicate frequently over a low-latency audio channel. Our experience designing and developing the game motivates significant discussion related to issues of general relevance to ubiquitous game architectures, including integration of heterogeneous components, monitoring, remote control and scalability.

Romain Pellerin, Nicolas Bouillot, Tatiana Pietkiewicz, Mike Wozniewski, Zack Settel, Eric Gressier-Soudan, Jeremy R. Cooperstock

Erratum to: Distributed Applications and Interoperable Systems

Abstract

Erratum to: T. Senivongse and R. Oliveira (Eds.) Distributed Applications and Interoperable Systems DOI: 10.1007/978-3-642-02164-0

The book was inadvertently published with an incorrect name of the copyright holder. The name of the copyright holder for this book is: © IFIP International Federation for Information Processing. The book has been updated with the changes.

Twittie Senivongse, Rui Oliveira

Backmatter

Titel: Distributed Applications and Interoperable Systems
herausgegeben von: Twittie Senivongse
Rui Oliveira
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-642-02164-0
Print ISBN: 978-3-642-02163-3
DOI: https://doi.org/10.1007/978-3-642-02164-0