共查询到20条相似文献,搜索用时 62 毫秒
1.
对等计算数据管理中的一个重要问题是如何有效地支持多维数据空间上的相似性搜索.现有的非结构化对等计算数据共享系统仅支持简单的查询处理方法,即匹配查询处理.将近似技术和路由索引结合在一起,设计了一种简单、有效的索引结构EVARI(扩展近似向量路由索引).利用EVARI,每个节点不仅可以在本地共享的数据集上处理范围查询,而且还可以将查询转发给最有希望获得查询结果的邻居节点.为了建立EVARI,每个节点使用空间划分技术概括本地的共享内容,并与邻居节点交换概要信息.而且,每个节点都可以重新配置自己的邻居节点,使得相关节点位置相互邻近,优化了系统资源配置,提升了系统性能.仿真实验证明了该方法的良好性能. 相似文献
2.
We consider the problem of efficiently computing distributed geographical k-NN queries in an unstructured peer-to-peer (P2P) system,in which each peer is managed by an individual organization and can only communicate with its logical neighboring peers.Such queries are based on local filter query statistics,and require as less communication cost as possible,which makes it more difficult than the existing distributed k-NN queries.Especially,we hope to reduce candidate peers and degrade communication cost.In this paper,we propose an efficient pruning technique to minimize the number of candidate peers to be processed to answer the k-NN queries.Our approach is especially suitable for continuous k-NN queries when updating peers,including changing ranges of peers,dynamically leaving or joining peers,and updating data in a peer. In addition,simulation results show that the proposed approach outperforms the existing Minimum Bounding Rectangle (MBR.)-based query approaches,especially for continuous queries. 相似文献
3.
This paper presents an efficient structured P2P overlay over MANET which better matches to the physical network in term of
routing. This feature is achieved by locally building up the minimum-spanning tree (MST) at each peer using the information
of the peer’s logical neighbors which are either directly connected (1-hop) or 2-hops away. Using this interconnection structure
among the peers, we design a new algorithm to distribute the contents information in the overlay by partitioning the identifier
(ID) space among the peers. In this algorithm, each peer maintains a disjoint portion of the ID space. The ID space at a peer
may be non-contiguous and each contiguous part is consecutive to the ID space of its directly connected neighbor peers. To
route the file-lookup query, each peer builds up a binary search tree (BST) using the knowledge of the ID space of itself
and of its directly connected neighbor peers. Simulation results show that our approach outperforms the existing approaches
in term of routing overhead, average file-discovery delay, false-negative ratio and average path-stretch value. 相似文献
4.
Yan Li Jyoti Ahuja Li Lao Jun-Hong Cui Shigang Chen 《Peer-to-Peer Networking and Applications》2011,4(1):3-22
A desired P2P file sharing system is expected to achieve the following design goals: scalability, routing efficiency and complex
query support. In this paper, we propose a powerful P2P file sharing system, PSON, which can satisfy all the three desired
properties. PSON is essentially a semantic overlay network of logical nodes. Each logical node represents a cluster of peers
that are close to each other. A powerful peer is selected in each cluster to support query routing on the overlay network
while the less powerful peers are responsible for the maintenance of shared contents. To facilitate query routing, super peers
are organized in form of a balanced binary search tree. By exploiting the concept of semantics, PSON can support complex queries
in a scalable and efficient way. In this paper, we present the basic system design such as the semantic overlay construction,
query routing and system dynamics. A load balancing scheme is proposed to further enhance the system performance. By simulation
experiments, we show that PSON is scalable, efficient and is able to support complex queries. 相似文献
5.
Jiann-Jone Chen Chia-Jung Hu Chun-Rong Su 《Multimedia, IEEE Transactions on》2008,10(2):209-220
We proposed to utilize the scalable peer-to-peer network to perform the content-based image retrieval and mining, i.e, P2P-CBIRM. The decentralized unstructured P2P model with certain overheads, i.e., peer clustering and update procedures, is adopted to compromise with the structured one while still reserving flexible routing control when peers join/leave or network fails. The peer CBIRM engine is designed to utilize multi-instance query with multi-feature types to effectively reduce network traffic while maintaining high retrieval accuracy. It helps to enhance the knowledge discovery and image data mining capability. The proposed P2P-CBIRM system provides the scalable retrieval and mining function that the query scope and retrieval accuracy can be adaptively and progressively controlled. To improve the query efficiency (recall-rate/query-scope), it effectively utilizes both: 1) forwarding query message (forward phase) to reduce the query scope and 2) transmitting retrieval results (backward phase) such that activated peers keep filtering high similarity images on the link-path toward the query peer. Experiments show that the query efficiency of the scalable retrieval approach is better than previous methods, i.e., firework query model and breadth-first search. It provides a scalable knowledge discovery platform for efficient image data mining applications. We also proposed to optimally configure the P2P-CBIRM system such that, under a certain number of online users, it would yield the highest recall rate. Simulations demonstrate that, with the optimal configuration, recall rates can be improved to 2.5 to 3 times larger while the network traffic of each peer is reduced to 30% of the original, under the same number of on-line users. 相似文献
6.
QUERY ROUTING IN A PEER-TO-PEER SEMANTIC LINK NETWORK 总被引:9,自引:0,他引:9
A semantic link peer-to-peer (P2P) network specifies and manages semantic relationships between peers' data schemas and can be used as the semantic layer of a scalable Knowledge Grid. The proposed approach consists of an automatic semantic link discovery method, a tool for building and maintaining P2P semantic link networks (P2PSLNs), a semantic-based peer similarity measurement for efficient query routing, and the schema mapping algorithms for query reformulation and heterogeneous data integration. The proposed approach has three important aspects. First, it uses semantic links to enrich the relationships between peers' data schemas. Second, it considers not only nodes but also the XML structure in measuring the similarity between schemas to efficiently and accurately forward queries to relevant peers. Third, it copes with semantic and structural heterogeneity and data inconsistency so that peers can exchange and translate heterogeneous information within a uniform view. 相似文献
7.
Anirban Mondal Sanjay Kumar Madria Masaru Kitsuregawa 《Distributed and Parallel Databases》2010,28(1):1-31
In mobile ad hoc peer-to-peer (M-P2P) networks, frequent network partitioning occurs due to peer movement or owing to peers
switching ‘off’ their mobile devices. This leads to typically low data availability in M-P2P networks, thereby necessitating
data replication. This work proposes E-ARL, which is a novel Economic scheme for Adaptive Revenue-Load-based dynamic replication of data in dedicated M-P2P networks with the aim of improving data availability. Thus, E-ARL considers a mobile cooperative environment, where
the MPs are working towards the same goal, and the network performance is facilitated by the economic scheme. E-ARL essentially
allocates replicas based on its economic scheme. Each data item has a price in virtual currency. E-ARL requires a query issuing peer to pay the price of its queried data item to the query-serving peer and a commission to relay peers in the successful query path. The main
contributions of E-ARL follow. First, it uses an economic scheme for efficiently managing M-P2P resources in a context-aware
manner by facilitating effective replica hosting and message relaying by peers. Second, it collaboratively performs bid-based replica allocation to facilitate better quality of service. Third, it incorporates both revenue-balancing and load-balancing
to improve peer participation and performance. Fourth, it conserves the energy of low-energy MPs to facilitate network connectivity.
Our performance evaluation shows that E-ARL is indeed effective in improving peer participation in M-P2P networks, thereby
improving query response times, query success rates, query hop-counts and replica allocation traffic. 相似文献
8.
9.
《Journal of Network and Computer Applications》2010,33(2):115-127
Unstructured Peer-to-Peer (P2P) networks have become a very popular architecture for content distribution in large-scale and dynamic environments. Searching for content in unstructured P2P networks is a challenging task because the distribution of objects has no association with the organization of peers. Proposed methods in recent years either depend too much on objects replication rate or suffer from a sharp decline in performance when objects stored in peers change rapidly, although their performance is better than flooding or random walk algorithms to some extent. In this paper, we propose a novel query routing mechanism for improving query performance in unstructured P2P networks. We design a data structure called traceable gain matrix (TGM) that records every query's gain at each peer along the query hit path, and allows for optimizing query routing decision effectively. Experimental results show that our query routing mechanism achieves relatively high query hit rate with low bandwidth consumption in different types of network topologies under static and dynamic network conditions. 相似文献
10.
在全分布无结构P2P中,节点通常组织成为覆盖网络,通过查询消息在网络中广泛转发实现盲目搜索。由于数据存放位置独立于数据内容,一个节点并不清楚哪些节点更容易命中查询,因此发现路由方向感,提高查询消息转发有效性,对全分布无结构P2P搜索具有重要意义。在相关工作中,主要从用户兴趣、本体论等语义角度聚类用户,减小搜索范围。但当前语义获取和语义描述等工作还不甚成熟,因此这些方法并没有得到广泛采用。提出了一种以访问频率为路由方向感的新型搜索方法QRRO。在QRRO中,每个节点被分配一权重标识;节点仅仅为访问频率与节点权重接近的数据建立索引;基于访问频率建立存储内容和存储位置之间的藕合关系,形成路由方向感。模拟实验表明,QRRO在提高搜索成功率、降低搜索路径长度方面是有效的。而且,由于访问频率是每个文件都具有的非语义属性,因此QRRO具有通用性。 相似文献
11.
一种高效的P2P环境中的窗口查询算法 总被引:1,自引:0,他引:1
随着多媒体以及P2P网络的发展,针对高维数据基于属性的窗口查询已经成为一个重要研究课题.提出了一种在超级节点P2P网络中有效解决高维数据的窗口查询算法,在每个单独的网络节点上,数据通过一种降维算法映射到一维空间,在超级节点上,构造数据的统计信息表以及构造网络查询树,算法在每次查询时,按照查询树的规则来访问整个网络,并利用统计信息剪枝网络中的节点查询,避免网络的泛洪.实验中使用了不同的数据集来评测算法的查询效率,结果表明该算法具有很高的查询效率. 相似文献
12.
Continually Answering Constraint <Emphasis Type="Italic">k</Emphasis>-<Emphasis Type="Italic">NN</Emphasis> Queries in Unstructured P2P Systems 下载免费PDF全文
Bin Wang Xiao-Chun Yang Guo-Ren Wang Ge Yu Lei Chen X. Sean Wang and Xue-Min Lin 《计算机科学技术学报》2008,23(4):538-556
We consider the problem of efficiently computing distributed geographical k-NN queries in an unstructured peer-to-peer (P2P) system, in which each peer is managed by an individual organization and can only communicate with its logical neighboring peers. Such queries are based on local filter query statistics, and require as less communication cost as possible which makes it more difficult than the existing distributed k-NN queries. Especially, we hope to reduce candidate peers and degrade communication cost. In this paper, we propose an efficient pruning technique to minimize the number of candidate peers to be processed to answer the k-NN queries. Our approach is especially suitable for continuous k-NN queries when updating peers, including changing ranges of peers, dynamically leaving or joining peers, and updating data in a peer. In addition, simulation results show that the proposed approach outperforms the existing Minimum Bounding Rectangle (MBR)-based query approaches, especially for continuous queries. 相似文献
13.
P2P搜索新技术:智能搜索技术 总被引:1,自引:0,他引:1
在P2P网络中正确高效地搜索信息十分重要,然而现有的搜索技术并不能很好地满足用户要求。文中提出了由历史记录、相似度和站点优先级3部分组成的新的信息搜索技术———智能搜索技术。在智能搜索技术中每个站点都各自记录以往搜索的历史记录,以此结合搜索要求计算出最可能拥有所需结果的站点,最后仅向这些站点发送搜索请求。通过在中间件上的测试,比较了不同信息搜索技术的性能,智能搜索技术能在使用较少搜索消息的情况下得到较高的搜索成功率。 相似文献
14.
Lefteris Sidirourgos George Kokkinidis Theodore Dalamagas Vassilis Christophides Timos Sellis 《Distributed and Parallel Databases》2008,23(1):45-68
P2P computing gains increasing attention lately, since it provides the means for realizing computing systems that scale to
very large numbers of participating peers, while ensuring high autonomy and fault-tolerance. Peer Data Management Systems
(PDMS) have been proposed to support sophisticated facilities in exchanging, querying and integrating (semi-)structured data
hosted by peers. In this paper, we are interested in routing graph queries in a very large PDMS, where peers advertise their
local bases using fragments of community RDF/S schemes (i.e., views). We introduce an original encoding for these fragments,
in order to efficiently check whether a peer view is subsumed by a query. We rely on this encoding to design an RDF/S view
lookup service featuring a statefull and a stateless execution over a DHT-based P2P infrastructure. We finally evaluate experimentally
our system to demonstrate its scalability for very large P2P networks and arbitrary RDF/S schema fragments, and to estimate
the number of routing hops required by the two versions of our lookup service.
Work done when T. Dalamagas was a postdoc researcher in NTUA. 相似文献
15.
Markus Bestehorn Christian von der Weth Erik Buchmann Klemens Böhm 《Distributed and Parallel Databases》2010,28(1):33-66
Recently, a number of query processors has been proposed for the evaluation of relational queries in structured P2P systems.
However, as these approaches do not consider peer or link failures, they cannot be deployed without extensions for real-world
applications. We show that typical failures in structured P2P systems can have an unpredictable impact on the correctness
of the result. In particular stateful operators that store intermediate results on peers, e.g., the distributed hash join,
must protect such results against failures. Although many replication schemes for P2P systems exist, they cannot replicate
operator states while the query is processed. In this paper we propose an in-query replication scheme which replicates the
state of an operator among the neighbors of the processing peer. Our analytical evaluation shows that the network overhead
of the in-query replication is in O(1) regarding network size, i.e., our scheme is scalable. We have carried out an extensive experimental evaluation using simulations
as well as a PlanetLab deployment. It confirms the effectiveness and the efficiency of the in-query replication scheme and
shows the effectiveness of the routing extension in networks of varying reliability. 相似文献
16.
The peer-to-peer (P2P) network structure is widely employed for video streaming applications because of its high stability, flexible extensibility, and ability to distribute data stream loading among different peer nodes. Numerous P2P schemes have been proposed for video on demand (VoD) applications. High video source searching cost and long response latency are always issues in dealing with VCR functionality, such as jump and fast-forward/rewind, because of asynchronous interactive and random join/leave behaviors of end users. To overcome this bottleneck, an interleaved video frame distribution (IVFD) scheme is proposed to support full VCR functionality in a P2P environment without searching for new sources. Instead of acquiring video stream data from a single parent peer in the published schemes, each child peer in the IVFD scheme can simultaneously acquire interleaved video data from multiple parent peers. When a client peer carries out arbitrary VCR operations, such as jump or fast-forward/rewind, its parent peers are still able to provide intermittent video stream data for the client peer; thus, no video source search is necessary. Simulation results reveal excellent load distribution performance and response latency for VCR operations in the proposed IVFD scheme. 相似文献
17.
This paper proposes a two-level P2P caching strategy for Web search queries. The design is suitable for a fully distributed service platform based on managed peer boxes (set-top-box or DSL/cable modem) located at the edge of the network, where both boxes and access bandwidth to those boxes are controlled and managed by an ISP provider. Our solution significantly reduces user query traffic going outside of the ISP provider to get query results from the respective Web search engine. Web users are usually very reactive to worldwide events which cause highly dynamic query traffic patterns leading to load imbalance across peers. Our solution contains a strategy to quickly ease imbalance on peers and spread communication flow among participating peers. Each peer maintains a local result cache used to keep the answers for queries originated in the peer itself and queries for which the peer is responsible for by contacting the Web search engine on-demand. When query traffic is predominantly routed to a few responsible peers our strategy replicates the role of “being responsible for” to neighboring peers so that they can absorb query traffic. This is a fairly slow and adaptive process that we call mid-term load balancing. To achieve a short-term fair distribution of queries we introduce a location cache in each peer which keeps pointers to peers that have already requested the same queries in the recent past. This lets these peers share their query answers with newly requesting peers. This process is fast as these popular queries are usually cached in the first DHT hop of a requesting peer which quickly tends to redistribute load among more and more peers. 相似文献
18.
19.
Diego Calvanese Giuseppe De Giacomo Domenico Lembo Maurizio Lenzerini Riccardo Rosati 《Information Systems》2008,33(4-5):360-384
We study peer-to-peer (P2P) data integration, where each peer models an autonomous system that exports data in terms of its own schema, and data interoperation is achieved by means of mappings among the peer schemas, rather than through a unique global schema. We propose a multi-modal epistemic logical formalization based on the idea that each peer is conceived as a rational agent that exchanges knowledge/belief with other peers, thus nicely modeling the modular structure of the system. We then address the issue of dealing with possible inconsistencies, and distinguish between two types of inconsistencies, called local and P2P, respectively. We define a nonmonotonic extension of our logic that is able to reason on the beliefs of peers under both local and P2P inconsistency tolerance. Tolerance to local inconsistency essentially means that the presence of inconsistency within one peer does not affect the consistency of the whole system. Tolerance to P2P inconsistency means being able to resolve inconsistencies arising from the interaction between peers. We study query answering in the new nonmonotonic logic, with the main goal of establishing its decidability and its computational complexity. Indeed, we show that, under reasonable assumptions on peer schemas, query answering is decidable, and is coNP-complete with respect to data complexity, i.e., the size of the data stored at the peers. 相似文献
20.
Query processing in large-scale unstructured P2P networks is a crucial part of operating such systems. In order to avoid expensive flooding of the network during query processing so-called routing indexes are used. Each peer maintains such an index for its neighbors. It provides a compact representation (data summary) of data accessible via each neighboring peer. An important problem in this context is to keep these data summaries up-to-date without paying high maintenance costs. In this paper, we investigate the problem of maintaining distributed data summaries in P2P-based environments without global knowledge and central instances. Based on a classification of update propagation strategies, we discuss several approaches to reduce maintenance costs and present results from an experimental evaluation. 相似文献