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

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

ISBN: (纸本)9783642006715

What-if analysis can provide more meaningful information than classical OLAP. Multi-scenario hypothesis based on historical data needs efficient what-if data view support. In general, delta table for what-if analysis is more general than other solutions such as query re-writing prototype of Sesame. Delta table is independent of base table and is more suitable to represent complex hypothetical updates and multi-version hypothetical updates. Due to low efficiency of traditional delta table merging algorithm which is based on set operation, there are few researches focus on delta table merging algorithm but on query re-writing algorithm. By analyzing the difference between what-if query and what-if analysis and improving the delta table merging algorithm, we propose novel algorithms without set operation of difference. Considering the feature of aggregate operations in OLAP analysis, pre-merge algorithm is presented without the generation of what if data view before group-bys in the scenario of SUM, AVERAGE and COUNT function OLAP queries. In our experiments, the pre-merge algorithm greatly improved the efficiency of delta table merging procedure which is close to base group-by statement and superior to the re-writing algorithm. A complete comparison between all candidate delta table merging algorithms and re-writing algorithm with different what-if update conditions of update, deletion, insertion and mixed what-if updates is exhibited in our experiments, the policy of what-if analysis among different types is also discussed. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Merging

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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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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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Configurable ranking for XML vague retrieval

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Journal of Computational information Systems 2009年第2期5卷 683-692页

作者： Jiang, Tengjiao Wan, Changxuan Liu, Xiping School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Jiangxi University of Finance and Economics Nanchang 330013 China

Ranking is one of the key factors for efficient and effective XML information retrieval. Compared with traditional IR, XML information retrieval has introduced many new challenges, one of which is that the traditional static document ranking method is no longer sufficient for ranking XML query results. As a result, we need a new ranking method. The paper studies the proper ranking model for XML vague retrieval. We first study the properties of vague retrieval over XML documents, and conclude the influencing factors of structure and content relaxation of XML vague retrieval. To improve recall and precision, we propose a new idea of confident structure query and vague structure query. Then, a configurable ranking model for twig pattern query results is proposed, in which users can configure query parameter. The model is designed to handle the new features of XML VCAS (vague content and structure). The architecture of corresponding XML search engine is also provided. © 2009 Binary information Press March, 2009.

关键词： XML

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Against Code Injection with System Call Randomization

Against Code Injection with System Call Randomization

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International Conference on Networks Security, Wireless Communications and Trusted Computing, NSWCTC

作者： Zhaohui Liang Bin Liang Luping Li Wei Chen Qingqing Kang Yingqin Gu Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China Beijing China Renmin University of China Beijing CN School of Information Renmin University of China China

ISBN: (纸本)9781424442232

The existing code injection attack defense methods have some deficiencies on performance overhead and effectiveness. In order to ensure the system performance, we propose a method that uses system call randomization to counter code injection attacks based on instruction set randomization idea. An injected code would perform its actions with system calls. System call randomization on operating system level will prevent the injected code from executing correctly. Moreover, with an extended compiler, our method can perform source code randomization during compiling and implement binary executable files randomization by feature matching. The experiments show that our method can effectively counter variety code injection attacks with low overhead.

关键词： Equations Counting circuits Operating systems Kernel Communication system security data security information security Wireless communication Computer networks Laboratories

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Rapid Resynchronization Method for Replication In-Memory databases Supporting Mobile Communication Applications

Rapid Resynchronization Method for Replication In-Memory Dat...

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Computer Science and information engineering, CSIE, WRI World Congress on FLAGGED

作者： Guoqiong Liao Jing Li Jiangxi Key Laboratory of Data and Knowledge Engineering Jiangxi University of Finance and Economics Nanchang China School of Information Technology Jiangxi University of Finance and Economics Nanchang China

In this paper, a rapid resynchronization method using intent logs is suggested for replication in-memory databases supporting mobile communication applications. Both the identifiers of unsynchronized segments and the identifiers of the slaves who have missed the updates in the segments are recorded in the intent logs. When receiving a resynchronization request from a slave, the master will scan the intent logs to find the unsynchronized segments for the salve, and then send the segments gotten directly from its memory to the slave. The performance results shown the intent logs method can reduce resynchronization time than methods using transaction logs.

关键词： Mobile communication Master-slave Transaction databases Availability Mission critical systems knowledge engineering Application software Finance Resumes Computer crashes

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Malicious Web Pages Detection Based on Abnormal Visibility Recognition

Malicious Web Pages Detection Based on Abnormal Visibility R...

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International Conference on E-Business and information System Security, EBISS

作者： Bin Liang Jianjun Huang Fang Liu Dawei Wang Daxiang Dong Zhaohui Liang Key Laboratory of Data Engineering and Knowledge Engineering MOE Renmin University of China Beijing China School of Information Renmin University of China Beijing China Renmin University of China Beijing CN

In recent years, Web sites have already become the attackers' main target. When attackers embed malicious code in the Web pages, they generally change the display mode of the corresponding HTML tags to make the display effect of malicious code invisible or almost invisible to the browser users. In this paper, the concept of abnormal visibility is proposed to describe the display feature setting of malicious code embedded. According to the concept, a malicious code detection method based on abnormal visibility recognition is designed and a prototype system is implemented. Compared to traditional methods and systems, the method has higher efficiency and less maintenance cost. Besides, a special-purpose JavaScript interpreter is implemented to get the execution output of browser-end scripts that are often used to generate malicious code dynamically by attackers. Experiments show that this system can detect most of the malicious Web pages efficiently and at the same time locate the malicious code in the source code accurately.

关键词： Web pages Displays Java Prototypes HTML Costs Invasive software Fingerprint recognition Laboratories data engineering

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Synchronous replication framework of databases servers supporting reliable electronic commerce applications

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Journal of Computational information Systems 2009年第2期5卷 849-858页

作者： Liao, Guoqiong Chen, Shijun School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China Siemens Ltd. China Corporate Technology Beijing 100102 China

To support electronic commerce applications with high reliability requirements, a synchronous replication framework of database servers is designed in this paper. At first, a three-tier architecture consisting of Web Servers (WS), Electronic Commerce Servers (ECS) and database Servers (DBS) for a reliable electronic commerce system is presented. Then, a primary copy synchronous replication model under the structure is given. Finally, a data synchronization method using one-phase commit (1PC) protocol for the model is discussed in details. The analysis result shows that 1PC can reduce response time than the two-phase commit protocol. © 2009 Binary information Press March, 2009.

关键词： Electronic commerce

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Efficient Processing of Global Top-k Aggregate Queries in Uncertain database

Efficient Processing of Global Top-k Aggregate Queries in Un...

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International Conference on information engineering and Computer Science (ICIECS)

作者： Xianli Xing Dexi Liu Principal's Office Jiangxi University of Finance and Economics Nanchang China School of Information Technology Jiangxi Key Laboratory of Data and Knowledge Engineering Jiangxi University of Finance and Economics Nanchang China

ISBN: (纸本)9781424449934

Top-k queries in uncertain databases are quite popular and useful due to its wide application usage. However, compared to top-k in traditional databases, queries over uncertain database are more complicated because of the existence of exponential possible worlds. A Top-k aggregate query ranks groups of tuples by their aggregate values, sum or average for example, and returns k groups with the highest aggregate values. As a powerful semantic of top-k, global top-k, returns A highest-ranked tuples according to their probabilities of being in the top-k anTopswers in possible worlds. We propose a dynamic programming based method to process global top-k aggregate queries in uncertain database, where the number of retrieved tuples and group states generated on these tuples are minimized. Experiment results show that our algorithm is effective.

关键词： Aggregates databases Finance Power generation economics Dynamic programming information technology Laboratories knowledge engineering information retrieval Performance analysis

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Chinese integral word segmentation recognition based on reliability

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Journal of information and Computational Science 2009年第1期6卷 533-542页

作者： Wan, Changxuan Wang, Fang School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Jiangxi University of Finance and Economics Nanchang 330013 China School of Humanities Nanchang University Nanchang 330013 China

As one part of preprocessing, automatic word segmentation is an key issue in Chinese information retrieval. Since integral words are put wholly together to compose into the more meaningful words and more express users' query minds in information retrieval, we combine the calculation of mutual information, prefix- and-suffix information of integral word with the reliability of composing into the integral word, and put forward three Chinese integral word segmentation recognition method based on reliability according to the characteristics of the integral words. Then, we design and realize the prototype system of three Chinese integral word segmentation recognition methods based on reliability. Finally, tests and analysis on 2nd SIGHAN (2005) PKU test corpus show that the recognition performance of the system is good, and can satisfy different needs at the same time. © 2009 Binary information Press.

关键词： Reliability

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