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RPE Query Processing and Optimization Techniques for xml Databases

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Journal of Computer Science & Technology 2004年第2期19卷 224-237页

作者： Guo-RenWang BingSun Jian-HuaLv GeYu DepartmentofComputerScience NortheasternUniversityShenyang110004P.R.China

An extent join to compute path expressions containing parent-children andancestor-descendent operations and two path expression optimization rules, path-shortening andpath-complementing, are presented in this paper. Path-shortening reduces the number of joins byshortening the path while path-complementing optimizes the path execution by using an equivalentcomplementary path expression to compute the original one. Experimental results show that thealgorithms proposed are more efficient than traditional algorithms.

关键词： xml regular path expressions query processing and optimization

xml-Based Information Fusion Architecture Based on Cloud Computing Ecosystem

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Computers, Materials & Continua 2019年第9期61卷 929-950页

作者： I-Ching Hsu Department of Computer Science and Information Engineering National Formosa UniversityHuwei TownshipYunlin County 632Taiwan

Considering cloud computing from an organizational and end user computing point of view,it is a new paradigm for deploying,managing and offering services through a shared *** development of cloud computing applications,however,are the lack of a uniformly approach to cope with the heterogeneous information *** leads cloud computing to inefficient development and a low potential *** study addresses these issues to propose a novel Web 2.0 Mashups as a Service,called WMaaS,which is a fundamental cloud service *** WMaaS is developed based on a xml-based Mashups Architecture(XMA)that is composed of Web 2.0 Mashups technologies,including Web Data,Web API,Web Interaction,and Web Presentation to associate with existing service *** demonstrate the feasibility of this approach,this study implemented a Ubiquitous Location-based Service System(ULSS)that is a cloud computing application developed based on WMaaS to provide continuous and location-based schedule information for organization monitoring and end user needs.

关键词： Web 2.0 mashups open data xml cloud computing

Tractable xml data exchange via relations

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Frontiers of Computer Science 2012年第3期6卷 243-263页

作者： Rada CHIRKOVA Leonid LIBKIN Juan L. REUTTER Department of Computer Science North Carolina State University Raleigh NC 27606 USA School of Informatics University of Edinburgh Edinburgh EH8 9AB UK

We consider data exchange for xml documents： given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has pri- marily been studied in the relational context, in which data- exchange systems have also been built. Since many xml documents are stored in relations, it is natural to consider using a relational system for xml data exchange. However, there is a complexity mismatch between query answering in relational and in xml data exchange. This indicates that to make the use of relational systems pos- sible, restrictions have to be imposed on xml schemas and mappings, as well as on xml shredding schemes. We isolate a set of five requirements that must be ful- filled in order to have a faithful representation of the xml data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in- lining technique for data-exchange tasks. Our key contribu- tion is to provide shredding algorithms for schemas, docu- ments, mappings and queries, and demonstrate that they en- able us to correctly perform xml data-exchange tasks using a relational system.

关键词： data exchange xml xml shredding inlining

Coordinating Mobile Agents by the xml—Based Tuple Space

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Journal of Computer Science & Technology 2002年第6期17卷 888-900页

作者：卢正鼎李春林李腊元 Department of Computer Science Huazhong University of Science and Technology Wuhan 430074 P.R. China Department of Computer Science Huazhong University of Science and Technology Wuhan 430074 P.R. ChinaDepartment of Computer Science Wuhan University of Technology Wuhan 430063 P.R. China Department of Computer Science Wuhan University of Technology Wuhan 430063 P.R. China

This paper presents Xspace, a programmable coordination paradigm for In-ternet applications based on mobile agents. The Xspace system fully exploits the advantages ofthe xml language and Linda-like coordination. It supports xml documents as tuple fields andmultiple matching routines implementing different relations among xml documents, includingthose given by xml query languages. The Xspace uses Java as the implementation language; itis based on object-oriented xmlized tuple spaces to implement a portable and programmablecoordination paradigm for mobile agents. The design and implementation procedures of Xspaceare described in this paper. Experiment and performance evaluation are also made. Finally,some conclusions and remarks are given.

关键词： xml mobile agent tuple space java coordination paradigm

CSchema： A Downgrading Policy Language for xml Access Control

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Journal of Computer Science & Technology 2007年第1期22卷 44-53页

作者：刘东喜 Department of Mathematical Informatics University of Tokyo Japan

The problem of regulating access to xml documents has attracted much attention from both academic and industry communities. In existing approaches, the xml elements specified by access policies axe either accessible or inaccessible according to their sensitivity. However, in some cases, the original xml elements are sensitive and inaccessible, but after being processed in some appropriate ways, the results become insensitive and thus accessible. This paper proposes a policy language to accommodate such cases, which can express the downgrading operations on sensitive data in xml documents through explicit calculations on them. The proposed policy language is called calculation-embedded schema （CSchema）, which extends the ordinary schema languages with protection type for protecting sensitive data and specifying downgrading operations. CSchema language has a type system to guarantee the type correctness of the embedded calculation expressions and moreover this type system also generates a security view after type checking a CSchema policy. Access policies specified by CSchema are enforced by a validation procedure, which produces the released documents containing only the accessible data by validating the protected documents against CSchema policies. These released documents are then ready to be accessed by, for instance, xml query engines. By incorporating this validation procedure, other xml processing technologies can use CSchema as the access control module.

关键词： access control programming language security policy type system xml

Efficient subtree results computation for xml keyword queries

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Frontiers of Computer Science 2015年第2期9卷 253-264页

作者： Ziyang CHEN School of Information Science and Engineering Yanshan University Hebei 066004 China Environmental Management College of China Hebei 066004 China The Key Laboratory for Computer Virtual Technology and System Integration of HeBei Province Yanshan University Hebei 066004 China

In this paper, we focus on efficient construction of restricted subtree （RSubtree） results for xml keyword queries on a multicore system. We firstly show that the perfor- mance bottlenecks for existing methods lie in 1） computing the set of relevant keyword nodes （RKNs） for each subtree root node, 2） constructing the corresponding RSubtree, and 3） parallel execution. We then propose a two-step generic top-down subtree construction algorithm, which computes SLCA/ELCA nodes in the first step, and parallelly gets RKNs and generates RSubtree results in the second step, where generic means that 1） our method can be used to compute dif- ferent kinds of subtree results, 2） our method is independent of the query semantics; top-down means that our method con- structs each RSubtree by visiting nodes of the subtree con- structed based on an RKN set level-by-level from left to right, such that to avoid visiting as many useless nodes as possible. The experimental results show that our method is much more efficient than existing ones according to various metrics.

关键词： xml SLCA/ELCA RSubtree RKNs parallel

Updating Recursive xml Views of Relations

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Journal of Computer Science & Technology 2008年第4期23卷 516-537页

作者：蔡冠球丛高樊文飞 Stratis D.Viglas Division of Information System School of Computer EngineeringNanyang Technological University Microsoft Research Asia Bell LaboratoriesmMurray Hill University of Edinburgh Edinburgh EH8 9LEScotlandU.K.

This paper investigates the view update problem for xml views published from relational data. We consider xml views defined in terms of mappings directed by possibly recursive DTDs compressed into DAGs and stored in relations. We provide new techniques to efficiently support xml view updates specified in terms of XPath expressions with recursion and complex filters. The interaction between XPath recursion and DAG compression of xml views makes the analysis of the xml view update problem rather intriguing. Furthermore, many issues are still open even for relational view updates, and need to be explored. In response to these, on the xml side we revise the notion of side effects and update semantics based on the semantics of xml views, and present efficient algorithms to translate xml updates to relational view updates. On the relational side, we propose a mild condition on SPJ views, and show that under this condition the analysis of deletions on relational views becomes PTIME while the insertion analysis is NP-complete. We develop an efficient algorithm to process relational view deletions, and a heuristic algorithm to handle view insertions. Finally, we present an experimental study to verify the effectiveness of our techniques.

关键词： xml xml publishing xml views view update

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Journal of Computer Science & Technology 2012年第1期27卷 195-212页

作者： Jun-Feng Zhou Tok Wang Ling Zhi-Feng Bao Xiao-Feng Meng School of Information Science and Engineering Yanshan UniversityQinhuangdao 066004China School of Information Renmin University of ChinaBeijing 100872China School of Computing National University of Singapore117417Singapore

We investigate the limitations of existing xml search methods and propose a new semantics, related relation- ship, to effectively capture meaningful relationships of data elements from xml data in the absence of structural constraints. Then we make an extension to XPath by introducing a new axis, related axis, to specify the related relationship between query nodes so as to enhance the flexibility of XPath. We propose to reduce the cost of computing the related relationship by a new schema summary that summarizes the related relationship from the original schema without any loss. Based on this schema summary, we introduce two indices to improve the performance of query processing. Our algorithm shows that the evaluation of most queries can be equivalently transformed into just a few selection and value join operations, thus avoids the costly structural join operations. The experimental results show that our method is effective and efficient in terms of comparing the effectiveness of the related relationship with existing keyword search semantics and comparing the efficiency of our evaluation methods with existing query engines.

关键词： xml XPath related axis entity graph schema summary

A Semantic Cache Framework for Secure xml Queries

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Journal of Computer Science & Technology 2008年第6期23卷 988-997页

作者：冯建华李国良塔娜 Department of Computer Science and Technology Tsinghua University

Secure xml query answering to protect data privacy and semantic cache to speed up xml query answering are two hot spots in current research areas of xml database systems. While both issues are explored respectively in depth, they have not been studied together, that is, the problem of semantic cache for secure xml query answering has not been addressed yet. In this paper, we present an interesting joint of these two aspects and propose an efficient framework of semantic cache for secure xml query answering, which can improve the performance of xml database systems under secure circumstances. Our framework combines access control, user privilege management over xml data and the state-of-the-art semantic xml query cache techniques, to ensure that data are presented only to authorized users in an efficient way. To the best of our knowledge, the approach we propose here is among the first beneficial efforts in a novel perspective of combining caching and security for xml database to improve system performance. The efficiency of our framework is verified by comprehensive experiments.

关键词： computer software xml semantic cache XPath