To Replicate or Not To Replicate Queries in the Presence of Autonomous Participants?

National audienceIn summary, the main contributions of this paper are as follows. 3 We formalize the query allocation problem and make precise query replication in the presence of autonomous participants (Section II). We introduce a global satisfaction notion to characterize the fact that (i) queries have different criticality for consumers; (ii) a consumer may receive less results than it expects; and (iii) a provider may perform queries for nothing (Section IV). We propose two automatic query replication algorithms, SbQR and SbQR+, that consider global satisfaction as the basis of their functionality to decide on-the-fly (i) which queries should be replicated and (ii) how many query replicas should be created (Section V). We experimentally demonstrate that SbQR: (i) significantly outperforms popular baseline algorithms and (ii) automatically adapts to the workload and the criticality of queries (Section VI).L'objectif d'un syst'eme largement distribu'e sur Internet est d'int'egrer des participants dont les sp'ecificit'es et motivations ne sont pas toujours clairement identifi'ees a priori. En particulier, des participants autonomes peuvent avoir des int'erˆets individuels sp'ecifiques vis-'a-vis des requˆetes, mais aussi des autres participants. Dans un tel contexte, un syst'eme ne prenant pas en compte les individualit'es provoque des d'eparts qui peuvent, par un effet domino, avoir des cons'equences d'evastatrices. La satisfaction des participants passe par la prise en compte de leurs int'erˆets lors de l'allocation des requˆetes, mais elle peut aussi ˆetre affect'ee par les probl'emes de pannes. La r'eplication des requˆetes est une solution permettant de r'esoudre ce dernier probl'eme. Cependant, la pr'esence de participants autonomes rend cette approche plus d'elicate. Non seulement la r'eplication de requˆete peut rapidement surcharger les participants et le syst'eme, mais l'int'erˆet des participants 'a traiter des requˆetes au cas o'u leurs coll'egues tombent en panne peut ˆetre assez faible. Les questions qui se posent alors naturellement sont est-il opportun de r'epliquer les requˆetes ?, mais aussi quelles requˆetes r'epliquer ? et dans ce cas avec quel niveau de r'eplication ? Dans cet article, nous proposons des r'eponses 'a ces questions en revisitant le probl'eme de la r'eplication du point de vue de la satisfaction des participants. Nous pr'esentons une nouvelle proposition, SbQR, qui d'ecide en temps r'eel si une requˆete doit ˆetre r'epliqu'ee et avec quel degr'e. Pour cela, SbQR s'appuie sur les notions de satisfaction des participants et de probabilit'e de panne. Dans la mesure o'u la r'eplication d'un grand nombre de requˆetes peut surcharger le syst'eme et donc impacter fortement sur ses performances, nous proposons une variante, SbQR+. L'id'ee directrice consiste, dans les p'eriodes de forte charge, 'a utiliser les ressources disponibles prioritairement pour le traitement des requˆetes critiques. Les requˆetes 'a faible impact sur la satisfaction des participants peuvent alors voir le nombre de leurs r'eplicats diminuer. Exceptionnellement elles peuvent mˆeme ˆetre totalement abandonn'ees. Nos exp'erimentations d'emontrent que ces solutions am'eliorent de mani'ere significative les algorithmes de r'ef'erence du point de vue des performances et de la satisfaction tout en s'adaptant dynamiquement aux 'evolutions de la criticit'e des requˆetes et des probabilit'es de pannes sans n'ecessiter aucun r'eglage ("tunning") particulier

WUW (What Users Want): A Service to Enhance Users' Satisfaction in Content-Based Peer-to-Peer Networks

20 pagesPeer-to-Peer (P2P) architectures are more and more used in Content Delivery Net- works (CDN), because the traditional client-server architectures are burdened by high distribution and maintenance cost, whereas in P2P systems those costs are almost negli- gible. In general, such applications do not take into account user preferences, other than QoS-related parameters. As users resources are the richness of P2P systems, we think it is important to satisfy their preferences concerning the usage of their resources. In this work we propose WUW (What Users Want), a service to improve users' satisfaction in a personal way. WUW runs on top of unstructured P2P systems, and its main goal is to allow users to strategically impact their local neighborhoods according to their own personal preferences. We present first results of experiments, deployed in a cluster, obtained with the prototype implementation of our service, which runs on top of Bit- Torrent, the most used file sharing protocol. We show that BitTorrent performances are not affected by the users strategic choices introduced by WUW. The advantage of our approach is that, without loosing performance, users can chose the peers they want to collaborate with according to their personal preferences

A framework for the dynamic management of Peer-to-Peer overlays

Peer-to-Peer (P2P) applications have been associated with inefficient operation, interference with other network services and large operational costs for network providers. This thesis presents a framework which can help ISPs address these issues by means of intelligent management of peer behaviour. The proposed approach involves limited control of P2P overlays without interfering with the fundamental characteristics of peer autonomy and decentralised operation. At the core of the management framework lays the Active Virtual Peer (AVP). Essentially intelligent peers operated by the network providers, the AVPs interact with the overlay from within, minimising redundant or inefficient traffic, enhancing overlay stability and facilitating the efficient and balanced use of available peer and network resources. They offer an “insider‟s” view of the overlay and permit the management of P2P functions in a compatible and non-intrusive manner. AVPs can support multiple P2P protocols and coordinate to perform functions collectively. To account for the multi-faceted nature of P2P applications and allow the incorporation of modern techniques and protocols as they appear, the framework is based on a modular architecture. Core modules for overlay control and transit traffic minimisation are presented. Towards the latter, a number of suitable P2P content caching strategies are proposed. Using a purpose-built P2P network simulator and small-scale experiments, it is demonstrated that the introduction of AVPs inside the network can significantly reduce inter-AS traffic, minimise costly multi-hop flows, increase overlay stability and load-balancing and offer improved peer transfer performance

Ubiquitous Semantic Applications

As Semantic Web technology evolves many open areas emerge, which attract more research focus. In addition to quickly expanding Linked Open Data (LOD) cloud, various embeddable metadata formats (e.g. RDFa, microdata) are becoming more common. Corporations are already using existing Web of Data to create new technologies that were not possible before. Watson by IBM an artificial intelligence computer system capable of answering questions posed in natural language can be a great example. On the other hand, ubiquitous devices that have a large number of sensors and integrated devices are becoming increasingly powerful and fully featured computing platforms in our pockets and homes. For many people smartphones and tablet computers have already replaced traditional computers as their window to the Internet and to the Web. Hence, the management and presentation of information that is useful to a user is a main requirement for today’s smartphones. And it is becoming extremely important to provide access to the emerging Web of Data from the ubiquitous devices. In this thesis we investigate how ubiquitous devices can interact with the Semantic Web. We discovered that there are five different approaches for bringing the Semantic Web to ubiquitous devices. We have outlined and discussed in detail existing challenges in implementing this approaches in section 1.2. We have described a conceptual framework for ubiquitous semantic applications in chapter 4. We distinguish three client approaches for accessing semantic data using ubiquitous devices depending on how much of the semantic data processing is performed on the device itself (thin, hybrid and fat clients). These are discussed in chapter 5 along with the solution to every related challenge. Two provider approaches (fat and hybrid) can be distinguished for exposing data from ubiquitous devices on the Semantic Web. These are discussed in chapter 6 along with the solution to every related challenge. We conclude our work with a discussion on each of the contributions of the thesis and propose future work for each of the discussed approach in chapter 7

Advanced Automation for Space Missions

The feasibility of using machine intelligence, including automation and robotics, in future space missions was studied

Enhanced Living Environments

This open access book was prepared as a Final Publication of the COST Action IC1303 “Algorithms, Architectures and Platforms for Enhanced Living Environments (AAPELE)”. The concept of Enhanced Living Environments (ELE) refers to the area of Ambient Assisted Living (AAL) that is more related with Information and Communication Technologies (ICT). Effective ELE solutions require appropriate ICT algorithms, architectures, platforms, and systems, having in view the advance of science and technology in this area and the development of new and innovative solutions that can provide improvements in the quality of life for people in their homes and can reduce the financial burden on the budgets of the healthcare providers. The aim of this book is to become a state-of-the-art reference, discussing progress made, as well as prompting future directions on theories, practices, standards, and strategies related to the ELE area. The book contains 12 chapters and can serve as a valuable reference for undergraduate students, post-graduate students, educators, faculty members, researchers, engineers, medical doctors, healthcare organizations, insurance companies, and research strategists working in this area

Proceedings of the Twenty-Third Annual Software Engineering Workshop

The Twenty-third Annual Software Engineering Workshop (SEW) provided 20 presentations designed to further the goals of the Software Engineering Laboratory (SEL) of the NASA-GSFC. The presentations were selected on their creativity. The sessions which were held on 2-3 of December 1998, centered on the SEL, Experimentation, Inspections, Fault Prediction, Verification and Validation, and Embedded Systems and Safety-Critical Systems

Remote Access to a Prototyping Laboratory

There is a growing global demand for continuing adult higher education particularly in science and engineering subjects. New technologies are emerging which would enable the development of a Remote Access Laboratory for rapid prototyping of Artificial Intelligence, as a learning environment for mechatronic engineering, in which high precision electromechanical devices are designed to exhibit autonomous behaviour. Secondary research investigated the learning theories for a Remote Access Laboratory, and the current practices for distance learning, involving groupware in shared activity 'collaboratories'. Having determined that the laboratory would need a multi-user interactive environment architecture, with the requirement for adaptability to rapid developments,a distributed software architecture was selected. The laboratory design was subsequently argued to be best served by Intelligent Agents in a Multi-Agent system. The aims of the research were to establish the viability of a Remote Access Laboratory for mechatronic experimentation, and to evaluate the technologies required to implement such a laboratory environment for rapid prototyping. These were achieved by developing a novel user interface, based on a multi-functional screen layout, and a graphical specification facility to provide robotic navigation that is intuitive to use and does not require text-based programming. The research investigated the prototyping of robotic behaviour, which used Programming by Demonstration as an innovative technique to prototype robot navigation. The method of designing behaviours met an anticipated need to allow the robot to interact with an environment, to achieve goals under conditions of uncertainty, while requiring a level of abstraction in the behaviour design. The interface structured a composite of the designed behaviours into prototype Artificial Intelligence using a hierarchical behaviour architecture, which complied with the principles of Object Orientated programming. This was subsequently a new and original programming method to facilitate rapid prototyping of Artificial Intelligence design and structuring. Experimentation involved 20 participants attempting to accomplish a series of tasks which involved using the prototyped interface and an existing text-based robot programming system. The participants were profiled by their formal qualifications, knowledge and experience. The experimental data obtained were used to establish a comparative measure of the prototype interface success compared with an existing distance-learning, home experiment kit, in the form of a small controllable model vehicle. The data obtained provided strong evidence to support the hypothesis that a Programming by Demonstration based system for rapid prototyping is more flexible and easier to use than a previously existing distance learning text-based system. The Programming by Demonstration system showed great promise, being quicker for prototyping, and more intuitive. The learning interface design pioneered new techniques and technologies for rapid prototyping of Artificial Intelligence in a Mechatronics Remote Access Laboratory