Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 14

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  peer-to-peer
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
The development of high speed mobile networks and the widespread use of smartphones have enabled users to easily obtain large data volumes via the Internet. This causes a heavy consumption of network resources, a burden on the available bandwidth. To solve such problems, a data offloading method with a wireless LAN access point has been used to distribute traffic from mobile to fixed networks. However, the method using wireless LAN access points can only change the communication paths but cannot reduce the overall traffic. This paper proposes a local cooperative data offloading system (LoCO) that reduces the overall traffic by sharing data, with direct communication between neighbors based on their location-related information. Moreover, the authors implemented the LoCO system on Android smartphones and clarified its performance in comparison with a traditional client/server system through experiments to download data in a real-world environment.
EN
This paper proposes a novel peer-to-peer communication framework to implement geographical location oriented networks, called G-LocON. Location-based services have been gaining in popularity, as proven by ridesharing and mobile games. Although these services have to construct geolocation oriented networks based on their users’ geographical locations, they completely rely on client/server models to communicate with neighboring terminals. G-LocON provides geolocation oriented device-to-device communication only with the current wireless technologies, such as LTE and Wi-Fi, cooperating with the global positioning system and peer-to-peer overlay networking. G-LocON will serve as a type of a mobile ad-hoc network in which devices located within the focusing area are capable of communicating directly. We developed a primitive Android application to implement the GLocON framework. Evaluation of the solution’s performance has verified the usefulness of the proposed system that offers an admissive transmission delay. Moreover, to confirm the application-related potential of the G-LocON framework, we also show a practical map software in which all neighboring mobile devices present in the focusing area are displayed.
EN
Most geolocation applications for mobile devices assume a constant connection with the network and high computational power nodes. However, with ever-developing devices it now becomes possible to establish peer-to-peer networks in case when the network can be unreachable due to special circumstances (like conflicts or natural disasters). In this paper, a method for clustering spatial data in mobile environment is discussed. A simple solution based on OPTICS algorithm with lexical distance is proposed for grouping the observations.
EN
Information and communication technologies enable the emergence of a new phenomenon called the “sharing economy”. An increasing number of articles in the media as well as debates about the positive and negative aspects of the sharing economy show a growing interest in the subject. The paper aims to review the different approaches to the definition of the sharing economy and to present the authors’ views on the concept. The reviewed literature reveals the main drivers for participating in the sharing economy. A survey was conducted to learn more about the motives of Lithuanian people participating in this concept. The survey reveals the following leading factors of using the sharing economy platforms: an easy way to make extra money; supporting individuals and/or small/independent companies; meeting new people and having an interesting experience/doing something most people haven’t tried yet. The survey also reveals that most of the respondents prefer to own things rather than share them. Despite the widespread popularity of the sharing economy platforms in the world, this phenomenon is in its infancy in Lithuania.
5
Content available remote Designing a software transactional memory for peer-to-peer systems
EN
Transactional memory is a rather novel approach to concurrency control in parallel computing, that has just recently found its way into distributed systems research. However, the research concentrates mainly on single processor solutions or cluster environment. In this paper we argue, that peer-to-peer systems would require a different design of transactional memory because of the increased failure-rate of nodes, slower network and possibility of network splits. We also present a few of our design ideas, namely increased performance and fault tolerance through the use of higher-level conflict detection and resolution via abstract data types and eventually consistency, that as we think could be important to a successful implementation of a scalable and resilient transactional memory.
PL
Nowe możliwości w realizacji automatyki zabezpieczeniowej wnoszą wymagania normy IEC 61850 (PN-EN 61850) opublikowanej w latach 2002 - 2010 w 14 częściach. Norma ujednolica zasady wymiany danych pomiędzy urządzeniami stacji elektroenergetycznych. Zasadniczym celem standardu 61850 jest zapewnienie kompatybilności urządzeń pochodzących od różnych producentów. Standard zakłada zastosowanie mikroprocesorowych urządzeń stacyjnych IED (ang. Intelligent Electronic Devices), takich jak zabezpieczenia cyfrowe, sterowniki polowe, stacyjne oraz przetworniki pomiarowe i aparaty wykonawcze, wyposażonych w odpowiednie interfejsy komunikacyjne. Norma przewiduje komunikację w najszybciej rozwijającej się technologii sieciowej Ethernet. Pozwala to na realizację najbardziej złożonych powiązań logicznych automatyki stacyjnej i między-stacyjnej przy wyeliminowaniu miedzianych kabli sterowniczych oraz sygnalizacyjnych. Jednakże, sprawdzenie współdziałania zastosowanych urządzeń IED wymaga czasochłonnych testów przeprowadzanych na budowanych bądź modernizowanych obiektach elektroenergetycznych.
EN
The requirements of IEC 61850 published in 2002 - 2010 (in 14 parts) establish new opportunities in the implementation of protective automation. The standard harmonizes the rules for data exchange and compatibility between substation devices supplied bydifferent manufacturers. Not only does system enable communication in the fastest growing Ethernet technology, but also eliminates the need for copper cables for control signal as well.The paper discusses the interoperability tests conducted by the author for five different manufacturers' protective relays.
EN
In this paper a modification of the widely used Kademlia peer-to-peer system to tactical networks is proposed. We first take a look at the available systems today to cover the range of possibilities peer-to-peer systems offer. We identify candidates for use in military networks. Then we compare two candidate systems in an environment with highly dynamic participants. The considered environment is focused on the special conditions in tactical networks. Then we give rationale for choosing Kademlia as a suitable system for tactical environments. Since Kademlia is not adapted to military networks, a modification to this system is proposed to adapt it to the special conditions encountered in this environment. We show that optimizations in the routing may lead to faster lookups by measuring the modified algorithm in a simulation of the target environment. We show also that the proposed modification can be used to extend the battery lifetime of mobile peer-to-peer nodes. Our results show that peer-to-peer systems can be used in military networks to increase their robustness. The modifications proposed to Kademlia adapt the system to the special challenges of military tactical networks.
EN
The most prevalent P2P application today is file sha ring, both among scientific users and the general public. Afundamental process in file sharing systems is the search mechanism. The unstructured nature of real-world largescale complex systems poses a challenge to the search me thods, because global routing and directory services are impractical to implement. This paper presents a new antcolony algorithm, Adaptive Neighboring-Ant Search (AdaNAS), for the semantic query routing problem (SQRP) in a P2P network. The proposed algorithm incor porates an adaptive control parameter tuning technique for runtime estimation of the time-to-live (TTL) of the ants. AdaNAS uses three strategies that take advantage of the local environment: learning, characterization, and explo ration. Two classical learning rules are used to gain ex perience on past performance using three new learning functions based on the distance traveled and the resources found by the ants. The experimental results show that the AdaNAS algorithm outperforms the NAS algorithm where the TTLvalue is not tuned at runtime.
EN
This article reports on the results of our measurement study of the Kad network. Although several fully decentralized peer-to-peer systems have been proposed in the literature, most existing systems still employ a centralized architecture. The Kad network is a notable exception. Since the demise of the Overnet network, the Kad network has become the most popular peer-topeer system based on a distributed hash table. It is likely that its user base will continue to grow in numbers over the next few years due to the system’s scalability and reliability. The contribution of the article is twofold. First, we compare the two networks accessed by eMule: the centralized paradigmof the eDonkey network and the structured, distributed approach pursued by the Kad network. We re-engineer the eDonkey server software and integrate two modified servers into the eDonkey network in order to monitor traffic. Additionally, we implement a Kad client exploiting a design weakness to spy on the traffic at arbitrary locations in the ID space. The collected data provides insights into the spacial and temporal distributions of the peers’ activity. Moreover, it allows us to study the searched content. The article also discusses problems related to the collection of such data sets and investigates techniques to verify the representativeness of the measured data. Second, this article shows that today’s Kad network can be attacked in several ways. Our simple attacks could be used either to hamper the correct functioning of the network itself, to censor content, or to harm other entities in the Internet not participating in the Kad network, such as ordinary web servers. While there are heuristics to improve the robustness of Kad, we believe that the attacks cannot be thwarted easily in a fully decentralized peer-to-peer system, i.e., without some kind of a centralized certification and verification authority. This result may be relevant in the context of the current debate on the design of a clean-slate network architecture for the Internet which is based on concepts known from the peer-to-peer paradigm.
10
EN
The paper describes aspects of integrating relational resources in an object-oriented data intensive grid with extensive description of a grid architecture. The presented solution is generic and allows utilizing native query optimizers of a relational resource (indices, fast joins, etc.), which can be effectively combined with an object query language (SBQL) optimization.
EN
Spatial databases present challenges to data management not found in typical RDBMS. Among these is the desire of users for highly distributed access to data. A new peer to peer database model is being developed that supports high distribution and concurrency of information access. Some aspects of the model are presented in this paper. However the new peer to peer model faces the critical problem of how to lock data as it becomes highly distributed. Conceptual methods borrowed from decision support and data mining are proposed to create a new type of locking model based on 3D volumetrics. The methods and mathematics proposed in this paper can become the basis for the implementation of a new type of peer to peer based spatial database system where spatial information flows to where it is needed on demand.
EN
We propose a grid programming approach using the ProActive middleware. The proposed strategy addresses several grid concerns, which we have classified into three categories. I. Grid Infrastructure which handles the resource acquisition and creation using deployment descriptors and Peer-to-Peer. II. Grid Technical Services which can provide non-functional transparent services like: fault tolerance, load balancing, and file transfer. III. Grid Higher Level programming with: group communication and hierarchical components. We have validated our approach with several grid programming experiences running applications on heterogeneous Grid resource using more than 1000 CPUs.
PL
W artykule przedstawiono pierwszy etap realizacji koncepcji DataGrid przy wykorzystaniu otwartej platformy transportowej opartej o sieć "każdy z każdym". Opisano część implementacyjną dotyczącą integracji obiektowych baz danych z istniejącym prototypem platformy transportowej. Prototypowe rozwiązanie daje możliwość realizacji sieci grid integrującej rozproszone obiektowe bazy danych.
EN
The paper presents the first stage of accomplishing a DataGrid concept by utilizing an open transport platform based on the peer--to-peer architecture. Implementation details concerning integration of object-oriented databases with the prototype of a transport platform are described. The prototype solution enables one to accomplish a grid network integrating distributed object-oriented data-bases.
PL
Artykuł prezentuje wyniki badań dotyczących implementacji otwartej platformy transportowej przeznaczonej do realizacji sieci grid utworzonej z obiektowych baz danych. Opisana implementacja jest oparta na wcześniej publikowanych założeniach. Prezentowanie zagadnienia obejmują: scentralizowaną architekturę sieci, w której działa platforma transportowa, wykorzystanie technologii JXTA do budowy wirtualnej sieci, podstawy budowy protokołu komunikacyjnego wraz z przykładem jego rozbudowy oraz zastosowanie platformy do integracji z zewnętrzną aplikacją użytkownika. Wszystkie opisane cechy działają w zrealizowanym prototypie.
EN
The paper presents the results of investigations concerning an open transport platform that can be used to build grid applications based on object-oriented databases. The described research has been focused on implementation of previously published project assumptions. The presented cases comprise: centralized architecture of a network for a transport platform, utilization of the JXTA technology for building a virtual network, foundations of a communication protocol for the network and an example of its application. An example of a transport platform integrated with an external user application is presented. All the described features are operating within the prototype.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.