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International audience; Over the last few years, social networks, mobile devices and personalized services have been heavily responsible for a substantial in- crease in remote services available over Internet. Consequently, service consumers have to discover remote services anytime, anywhere across networks boundaries making thus service discovery, and their underlying Service Discovery Protocols (SDPs) more important than ever. In this paper, we introduce ZigZag, a middleware to reuse and extend current SDP, designed for local networks, to discover available services across network boundaries as required in Future Internet. Our approach is based on protocol translation to enable service discovery irrespective of their underlying SDP. Further, we provide a thorough evaluation to validate our approach.

Current publish/subscribe systems provide very limited support to modify subscriptions dynamically. Consequently, they cannot efficiently control the flow of events between publishers and subscribers, which may lead to unnecessary network traffic. In addition, it is not possible to automatically subscribe or unsubscribe to a service depending on certain context of use. This implies for developers to manually manage subscriptions (e.g., taking care of when to cancel or re-issue a subscription), which may result in inappropriate subscription states (e.g., subscriptions that are cancelled too late). In this paper, we propose the concept of dynamic subscription mechanisms that improves the expressiveness and flexibility of subscriptions. We introduce a new dimension to a subscription that allows a subscriber to express the flow of matched events, and when a new subscription can be (re)issued. We validate our claims for improved flexibility and expressiveness by providing language abstractions and a prototype implementation of a dynamic subscription mechanism framework called Flexub that supports a variation of subscription mechanisms. When compared to existing subscription models, our experiment results show that the support for dynamic subscription mechanisms greatly reduces network traffic of events sent from publishers to the subscribers. In addition, our approach reduces the workload on the subscriber side. ispartof: pages:132-139 ispartof: Distributed Applications and Interoperable Systems vol:7272 pages:132-139 ispartof: DAIS 2012 location:Stockholm, Sweden date:13 Jun - 16 Jun 2012 status: published

International audience; The phenomenon of social networking has entered the lives of millions of people via the ubiquitous Web-based platforms such as Facebook and Google+ which are centralized platforms completely controlled by single entities. However, a complete parallel message-passing infrastructure already exists and has the benefit of 30 years experience and investments: the SMTP e-mail network, which together with the latest technologies can be utilized to provide a completely decentralized, convenient, private and even fault-tolerant social networking platform. This work in progress aims to design and implement a proof of concept of such idea.

International audience; Secure systems are usually complex since stateful security mechanisms like authentication and authorization have to be integrated into the functional behavior at various places. The security operations are, in general, interdependent such that events at one place may influence the behavior at other places. Thus, the composed specification of a system is neither easy to understand nor to analyze, and a faulty integration of the security mechanisms is often overseen. In this paper, we introduce the concept of singletons into our model-based engineering technique SPACE which facilitates a straightforward integration of security aspects. The behavior of a security protocol is encapsulated in a building block using a two-view interface contract. One view of the contract is quite simple and suffices for the correct integration of the block into a system specification. The other view is more complex but has to be considered only by the block designers to verify that the behavioral model in the block fulfills its interface contract. We exemplify the singletons by means of an authorization mechanism and discuss how to prove that the two views of its interface contract are consistent.

International audience; Online shopping has reached an unforeseen success during the last decade thanks to the explosion of the Internet and the development of dedicated websites. Nonetheless, the wide diversity of e-commerce websites does not really foster the sales, but rather leaves the customer in the middle of dense jungle. In particular, finding the best offer for a specific product might require to spend hours browsing the Internet without being sure of finding the best deal in the end. While some websites are providing comparators to help the customer in finding the best offer meeting her/his requirements, the objectivity of these websites remains questionable, the comparison criteria are statically defined, while the nature of products they support is restricted to specific categories (e.g., electronic devices). In this paper, we introduce MACCHIATO as a user-centered platform leveraging online shopping. MACCHIATO implements the principles of the Internet-of-Things by adopting the REST architectural style and semantic web standards to navigate product databases exposed on the Internet. By doing so, customers keep the control of their shopping process by selecting the stores and comparing the offers according to their own preferences.

International audience; Component-based platforms are widely used to develop and deploy distributed pervasive system that exhibit a high degree of dynam- icity, concurrency, distribution, heterogeneity, and volatility. This paper deals with the problem of ensuring safe yet efficient dynamic adaptation in a distributed and volatile environment. Most current platforms pro- vide capabilities for dynamic local adaptation to adapt these systems to their evolving execution context, but are still limited in their ability to handle distributed adaptations. Thus, a remaining challenge is to safely propagate reconfiguration policies of component-based systems to ensure consistency of the architecture configuration models over a dynamic and distributed system. In this paper we implement a specific algorithm rely- ing on the models at runtime paradigm to manage platform independent models of the current system architecture and its deployed configuration, and to propagate reconfiguration policies. We evaluate a combination of gossip-based algorithms and vector clock techniques that are able to propagate these policies safely in order to preserve consistency of archi- tecture configuration models among all computation nodes of the system. This evaluation is done with a test-bed system running on a large size grid network.

Lecture Notes in Computer Science, Volume 7272, 2012., The distributed aggregation of simple aggregates such as minima/maxima, counts, sums and averages have been studied in the past and are important tools for distributed algorithms and network co- ordination. Nonetheless, this kind of aggregates may not be comprehen- sive enough to characterize biased data distributions or when in presence of outliers, making the case for richer estimates. This work presents Spectra, a distributed algorithm for the estimation of distribution functions over large scale networks. The estimate is available at all nodes and the technique depicts important properties: robustness when exposed to high levels of message loss, fast convergence speed and fine precision in the estimate. It can also dynamically cope with changes of the sampled local property and with churn, without requiring restarts. The proposed approach is experimentally evaluated and contrasted to a competing state of the art distribution aggregation technique., (undefined)

International audience; Slicing a large-scale distributed system is the process of autonomously partitioning its nodes into k groups, named slices. Slicing is associated to an order on node-specific criteria, such as available storage, uptime, or bandwidth. Each slice corresponds to the nodes between two quantiles in a virtual ranking according to the criteria.For instance, a system can be split in three groups, one with nodes with the lowest uptimes, one with nodes with the highest uptimes, and one in the middle. Such a partitioning can be used by applications to assign different tasks to different groups of nodes, e.g., assigning critical tasks to the more powerful or stable nodes and less critical tasks to other slices.Assigning a slice to each node in a large-scale distributed system, where no global knowledge of nodes’ criteria exists, is not trivial. Recently, much research effort was dedicated to guaranteeing a fast and correct convergence in comparison to a global sort of the nodes.Unfortunately, state-of-the-art slicing protocols exhibit flaws that preclude their application in real scenarios, in particular with respect to cost and stability. In this paper, we identify steadiness issues where nodes in a slice border constantly exchange slice and large memory requirements for adequate convergence, and provide practical solutions for the two. Our solutions are generic and can be applied to two different state-of-the-art slicing protocols with little effort and while preserving the desirable properties of each. The effectiveness of the proposed solutions is extensively studied in several simulated experiments.

International audience; Situation-awareness is the ability of applications to adapt to the current situation of their users. For situation-awareness to be truly pervasive it should support the individual needs of every user, everywhere. We present a middleware for pervasive situation-awareness based on the idea of separating the features of a situation from the specification of how it should be recognised. The features of a situation can be seen as an interface that can be easily customised to satisfy individual user needs, while alternative specifications can be used to recognise a situation in different environments. The middleware views situations as collections of roles that individuals and devices play. Its implementation follows an agent-based architecture where collaborating agents acquire and reason over context data. We also show that the middleware can recognise a variety of highly customised situations using alternative specifications with performance that is acceptable for interactive situation-aware applications in realistic deployment sizes.

International audience; As personal devices become smarter, opportunities arise for sharing services, applications and data between them. While web technologies hold the promise of being a unifying layer, browsers lack functionality for supporting inter-device communication, synchronization, and security. To address this, we designed webinos: a cross-device distributed middleware providing interoperability, compatibility and security for mobile web applications. In this paper we present a case study of the webinos project, showing how the architecture of webinos was specified, designed and implemented, and reflect on several lessons learned.