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International Workshop on database technology and Applications

作者： Tian Xia Key Laboratory of Data Engineering and Knowledge Engineering School of Information Resource Management Renmin University of China Beijing China

Ajax is an important approach for improving rich interactivity between Web server and end users during Web 2.0 eras. At the same time, the structured data in AJAX Web pages can not be extracted easily due to its asynchronous loading. In this paper, we propose a technique for extracting the structured data from the AJAX based Web pages. Firstly, an AjaxFetcher component is created to fetch the dynamic page content by using an embedded browser. Secondly, two different strategies are used to extract the structured data from the obtained page contents. Especially for the page that contains multi-records, an automatic approach to determine each possible record is proposed. Experimental results show that fetching Ajax pages and extracting the structured data from them is feasible.

关键词： data mining Web pages databases Uniform resource locators Laboratories data engineering knowledge engineering information resources information management knowledge management

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Operating systems support for process dynamic integrity measurement

Operating systems support for process dynamic integrity meas...

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IEEE Youth Conference on information, Computing and Telecommunication, YC-ICT

作者： Chenglong Wei Shaohua Song Wen Hua Pan Bian School of Information Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Renmin University of China Beijing China

Facing limitations of existing systems for process integrity measurement, we put forward a method with its prototype system PDIMS to measure process runtime integrity. Based on structure of process and format of executable file, PDIMS anatomizes the codepage layout of runtime process. Combining OS mechanisms and modern CPU's support for code execution, PDIMS catches and measures code page in the kernel when it executes. PDIMS depends on CPU's non-executable bit to detect code execution and on the binary format of executables of the process as criterion to verify code modifications in kernel. PDIMS provides trustworthy information about whether a running process is modified. PDIMS introduces less than 4% overhead to OS.

关键词： Operating systems Kernel Modems Computer security Runtime Protection databases knowledge engineering Prototypes Computer architecture

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DB Facade: A Web Cache with Improved data Freshness

DB Facade: A Web Cache with Improved Data Freshness

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International Symposium on Electronic Commerce and Security

作者： Xiongpai Qin Xiaoyun Zhou Key Laboratory of Data Engineering and Knowledge Engineering School of Information Renmin University of China Beijing China School of Information and Electrical Engineering China University of Mining and Technology Xuzhou Jiangsu China

Traditional Web database cache techniques have a major disadvantage, namely poor data freshness, because they employ an asynchronous data refresh strategy. A novel Web database cache, DB Facade, is proposed in this paper. DB Facade uses a main memory database to cache result sets of previous queries for subsequent reusing. Updates on backend database system are managed by delta tables, and then propagated to Web database cache in a near real-time manner, hence guarantee the freshness of data. DB Facade off loads query burden from backend database systems, and exploits the power of main memory database system to boost query performance. TPC-W testing result shows that the system's performance increases by about 17 percent.

关键词： database systems System testing Assembly systems Web pages Web server Electronic commerce data security information security Laboratories data engineering

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Selectivity Estimation of Correlated Properties in RDF data for SPARQL Query Optimization

Selectivity Estimation of Correlated Properties in RDF Data ...

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Fifth International Conference on Semantics,knowledge and Grid(第五届语义、知识与网格国际会议 SKG 2009)

作者： Bin Lv Xiaoyong Du Yan Wang Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education School of Information Renmin University of China Beijing 100872 China

Nowadays mainstream RDF Repository Systems are based on RDBMS. The SPARQL query engine translates a SPARQL query into a SQL one, and then the RDBMS executes the SQL query. However the RDBMS optimizers, which usually assume that columns are statistically independent, often underestimate the selectivity of conjunctive predicates and choose a bad query execution plan. It is important for query optimizers to detect correlations among properties. We propose a way of computing property correlations based on ontology itself in order to improve the execution performance of the SQL translated from SPARQL statement queries.

关键词： Ontology SPARQL SQL Property Correlation Query optimization

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Interference and power constrained Broadcasting and Multicasting in wireless ad hoc networks with directional antennas

Interference and power constrained Broadcasting and Multicas...

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IEEE Internatonal Conference on Mobile Adhoc and Sensor Systems (MASS)

作者： Zheng Li Deying Li Ming Liu Key Laboratory of Data Engineering and Knowledge Engineering MOE School of Information Renmin University of China China School of Computer Science and Engineering University of Electronic Science and Technology Chengdu China

ISBN: (纸本)9781424451142

Broadcasting/Multicasting problems have been well studied in wireless ad hoc networks. However, only a few approaches take into account the low interference and energy efficiency as the optimization objective simultaneously. In this paper, we study the interference and power constrained broadcast/multicast and the delay-bounded interference and power constrained broadcast/multicast routing problems in wireless ad hoc networks using directional antennas. We propose an approximation and a heuristic algorithm for the two problems, respectively. Importantly, motivated by the study of above optimization problems, we propose approximation schemes for two multi-constrained directed Steiner tree problems, respectively. Broadcast/Multicast message by using the trees found by our algorithms tend to have less channel collisions and higher network throughput. The theoretical results are corroborated by simulation studies.

关键词： Interference constraints Broadcasting Mobile ad hoc networks Directional antennas Multicast algorithms Energy efficiency Routing Approximation algorithms Heuristic algorithms Throughput

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Ontology-based Categorization of Web Search Results Using YAGO

Ontology-based Categorization of Web Search Results Using YA...

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The Second International Joint Conference on Computational Science and Optimization(CSO 2009)(2009 国际计算科学与优化会议)

作者： Anjian Ren Xiaoyong Du Puwei Wang Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education China School of Information Renmin University of China Beijing 100782 China

One of the major limitations of current search engines is that users could not quickly locate what they want if the input query is too general. Some existing techniques try to cluster web search results into groups so as to user's quick browsing. In this paper, we present a new approach to categorize the web search results by using YAGO ontology. It utilizes the YAGO ontology to automatically generate categories for the user's specific query and classify the search results into appropriate categories. Our experimental results indicate that our method is feasible and effectiveness.

关键词： Ontologies Web search Feedback Image retrieval information retrieval Image databases Humans Set theory information systems Radio frequency

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Generating multi-page mirror site from ajax interfaces

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Journal of information and Computational Science 2009年第2期6卷 985-991页

作者： Xia, Tian Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China Beijing 100872 China School of Information Resource Management Renmin University of China Beijing 100872 China

Ajax is an important approach for improving rich interactivity between web server and end users during Web 2.0 eras. At the same time, AJAX web pages can not be indexed by search engines due to its asynchronous loading. In this paper, we propose a technique for generating the traditional multi-page mirror site from the AJAX based web pages. Firstly, a page state structure to represent any dynamic state of Ajax page is defined, and a states repository is proposed to store the different states. Secondly, each state is fetched from repository and rendered by an embedded browser to get the dynamic DOM, and the click events of candidate clickable elements are fired, then new states are created and stored to repository. Finally, page states are linked and transformed into static HTML files. Experimental results show that mirroring Ajax sites is feasible, though there still have some limitations need to be improved later. Copyright ©2009 Binary information Press.

关键词： Websites

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Incremental computation for MEDIAN cubes in what-if analysis

Incremental computation for MEDIAN cubes in what-if analysis

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

作者： Xiao, Yanqin Zhang, Yansong Wang, Shan Chen, Hong Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China MOE Beijing 100872 China School of Information Renmin University of China Beijing 100872 China Computer Center Hebei University Baoding Hebei 071002 China Department of Computer Science Harbin Finance College Harbin 150030 China

ISBN: (纸本)9783642006715

What-if analysis is an important type of DSS analysis processing procedure. It analyzes hypothetical scenarios based on historical data. The data cube view must be updated when the what-if condition is changed. Since source data must be kept in order to compute the new aggregate value when new tuples are inserted or deleted, in what-if analysis, incrementally computing a data cube for holistic aggregation functions is a difficult problem. In this paper, we adopt delta cube strategy and work area technique to incrementally compute data cube for MEDIAN function. The size of work area has important influence on the efficiency of the incremental computing. This paper optimizes the size of work area based on the number and the cardinality of dimension attributes of the cuboid. Performance study shows that our algorithms are effective over large databases. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Geometry

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ARRAY: A non-application-related, secure,wide-area disaster recovery storage system

ARRAY: A non-application-related, secure,wide-area disaster ...

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2009 IEEE International Symposium on Parallel and Distributed Processing with Applications, ISPA 2009

作者： Zeng, Lingfang Feng, Dan Veeravalli, Bharadwaj Wei, Qingsong Division of Data Storage System Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage Wuhan 430074 China School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China Department of Electrical Computer Engineering National University of Singapore Singapore 117608 Singapore Data Storage Institute Singapore 117608 Singapore

ISBN: (纸本)9780769537474

With our society more information-driven, we have begun to distribute data in wide-area storage systems. At the same time, both physical failure and logic error have made it difficult to bring the necessary recovery to bear on remote data disaster, and understanding this proceeding. We describe ARRAY, a system architecture for data disaster recovery that combines reliability, storage space, and security to improve performance for data recovery applications. The paper presents an exhaustive analysis of the design space of ARRAY systems, focusing on the trade-offs between reliability, storage space, security, and performance that ARRAY must make. We present RSRAII (Replication-based Snapshot Redundant Array of Independent Imagefiles) which is a configurable RAIDlike data erasure-coding, and also others benefits come from consolidation both erasure-coding and replication strategies. A novel algorithm is proposed to improve snapshot performance referred to as SMPDP (Snapshot based on Multi-Parallel Degree Pipeline).

关键词： Recovery

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Efficient incremental computation of CUBE in multiple versions what-if analysis

Efficient incremental computation of CUBE in multiple versio...

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

ISBN: (纸本)9783642006715

What-if analysis is an important method to analyze the hypothetical scenarios based on the historical data. It provides useful information for the decision- maker. Multiple versions are critical to what-if analysis. In this paper, we analyze the problem of multiple versions data processing and the incremental computation of cubes in what-if analysis, proposing a strategy to process multiple versions of what-if data. Our solution can adopt different data processing methods according to the type of aggregate functions, the efficiency of multiple versions data processing is improved. Furthermore, we proposes an algorithm of incremental computation of CUBE for max(min) function to reduce the access time of fact table, and the experimental results showed that the performance is improved about 10%. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Decision making

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