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RISS 인기검색어
- 검색키워드
- 저자 : Husheng Liao,Xiaoqing Li,Hang Su (검색결과 6 건)
- 무료
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A Formal Description of XML Tree Pattern Query for XQuery Language
Husheng Liao,Xiaoqing Li,Hang Su 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.5
In order to express tree pattern query in query plan and take advantage of formal method to analyze its behavioral characteristics, this paper present a formal description of tree pattern query based on functional language and denotational semantics. This description major focuses on behavior of a tree pattern query on matching against an eXtensible Markup Language (XML) document tree. First, we introduce a formal definition for a kind of extended generalized tree pattern (GTP++). Then we present a functional tree pattern description language (XTPL) for GTP++ and give its complete denotational semantics based on a novel data structure, named WTree, which efficiently organizes this typical XML data query results and provides flexible data access method. In the end, we present the formal semantics of identifying tree pattern from path expressions. By using formal methods, the semantics of tree pattern query is consistent and analyzable. As the core operation of XML query, this formal description can provide an initial step for analyzing the correctness of XML queries, and improves the reliability and robustness of query processing methods.
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An Accurate Identification of Extended XML Tree Pattern for XQuery Language
Husheng Liao,Xiaoqing Li,Junpeng Chen 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.5
In order to utilize high-performance XML tree pattern query (TPQ) for implementing of XQuery language effectively, it is necessary to analysis the query plan and identify tree pattern from it. In this paper, we extend the functional intermediate language FXQL, which is used to implement XQuery language, with an extended XML generalized tree pattern representation (GTP++). Then, we propose an XML tree pattern identification approach, which is composed of a suit of query expression rewriting rules for extracting tree pattern and a GTP++ construction algorithm. Based on this approach, both explicit and implied propositional logic, various structural constraints and predicates can be extracted across nested query blocks in XQuery FLWOR expressions. The tree pattern identified by this approach is more holistic and precisely than previous methods. The approach expands the application of XML tree pattern query technology in the implementation of XQuery language. Experiments show its effectiveness and practicability.
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Intersection Checking for Regular Expressions Based on Inference System
Jia Liu,Husheng Liao 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.4
Decision problem of intersection checking for regular expressions plays an important role in the XML type checking. The typical technique is converted into the problem of automata intersection, which may generate a lot of redundant computing during the conversion. In the present paper, according to the features of XML schema languages, a new intersection checking algorithm based on inference system for regular expressions is proposed. This method is derived directly based on regular expression without the need for any conversion. For general regular expressions that is exponential time algorithm, but without constructing automata and for some special cases, especially for the one-unambiguous regular expressions used in XML type checking, is the polynomial time algorithm. Proofs of the correctness and completeness of the inference rules are given. Experiment results show that our approach are more effective than automatic approach in practical.
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Query XML Streaming Data with List
He Zhixue,Liao Husheng 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.10
There has been a growing practical need for querying XML streaming data efficiently. Stream requires to be read sequentially and only once into memory, the query must be processed on the fly. QXSList technique is proposed for massive data processing, which takes the SAX events sequence as input, buffer the incoming elements for further processing, remove unnecessary elements from the buffer in time, and give the results on the fly. Data model and algorithm integrated framework are defined, the integrate methods of how to process predicate and wildcard are discussed respectively. Level value is used for determining the relationship of two elements and relational pointers are constructed for linking multi lists in this method. The experimental results show that our approach is effective and efficient on this problem, and outperforms the state-of-the-art algorithms and query engines especially for data size is very large. At the same time, memory usage is nearly constant.
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FOCCX: An Optimistic Concurrency Control Protocol over XML
Weifeng Shan,Husheng Liao 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.2
XML concurrency control protocol (CCP) is used to guard the consistence and isolation of transactions in Native XML databases. Experiments show that locking overhead of existing approaches based on locking may be huge, especially in the applications with few or without conflicts. Optimistic concurrency control (OCC) is an alternative to locking. This paper presents a new optimistic approach for concurrency control over XML documents named FOCCX (Forward oriented Optimistic Concurrency Control over XML) facing XPath-based API. FOCCX increases the degree of transaction concurrency. This is achieved by aborting the current transaction when a potential UPDATE-UPDATE conflict taking place as early as possible, and reduces comparison times by checking a small write set against read set of a limited number of concurrent transactions. Experimental results show that our protocol has superior performance to approaches based on Backward Oriented mechanism (BOCC).
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