XCQ: A queriable XML compression system

Ng, Wilfred; Lam, Wai-Yeung; Wood, Peter T.; Levene, Mark

doi:10.1007/s10115-006-0012-z

Cited by 45 publications

(27 citation statements)

References 20 publications

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“…answering queries, may not be possible without an expensive decompression step. Special compressors for XML data can be divided into two groups: those which produce queryable compressed XML data [21,19,5] and those which do not [29,15,6]. A fundamental problem is that the footprint of these XML compressors and simple compressors is many times higher than the available memory on sensor nodes.…”

Section: Related Workmentioning

confidence: 99%

Efficient XML Usage within Wireless Sensor Networks

Hoeller¹,

Reinke²,

Neumann³

et al. 2008

Proceedings of the 4th International ICST Conference on Wireless Internet

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Integrating wireless sensor networks in heterogeneous networks is a complex task. A reason is the absence of a standardized data exchange format that is supported in all participating sub networks. XML has evolved to the de facto standard data exchange format between heterogeneous networks and systems. However, XML usage within sensor networks has not been introduced because of the limited hardware resources. In this paper, we introduce XML template objects making XML usage applicable within sensor networks. This new XML data binding technique provides significant high compression results while still allowing dynamic XML processing and XML navigation. This is a step towards more complex but exchangeable data management in sensor networks and the extension of the service-oriented paradigm to sensor network application engineering.

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Section: Related Workmentioning

confidence: 99%

Efficient XML Usage within Wireless Sensor Networks

Hoeller¹,

Reinke²,

Neumann³

et al. 2008

Proceedings of the 4th International ICST Conference on Wireless Internet

View full text Add to dashboard Cite

show abstract

“…(cf. a full explanation of the DSP algorithm and a detailed example of generating the structure and data streams can be found in Sections 3.2 and 3.3 in [12]. )…”

Section: Introductionmentioning

confidence: 99%

“…Some preliminary ideas about the query evaluation strategy were highlighted in our earlier study [12], in which the PPB engine was developed to support the logical operators of core XPath queries: "not", "or" and "and"; along with the comparison operators: "=", " =", ">", and "<". The PPB engine also supports "CONTAINS" (i.e., for a substring) and "STARTS-WITH" for strings.…”

Section: Introductionmentioning

confidence: 99%

“…The term "stream" used in our subsequent discussion originated from our XCQ compression methodology proposed in [12]. In a nut shell, given an XML document, we achieve the compression using a DTD Tree and SAX Event Stream Parsing (DSP) technique.…”

Section: Introductionmentioning

confidence: 99%

“…The data blocks in the data streams are compressed individually using Gzip [23]. The low-level compressor can be replaced by another generic one such as Bzip2 library as reported in [12], which could gain a better compression ratio at the expense of compression time. The underlying idea of query evaluation is that, by utilizing the structure stream, we only need to decompress on the fly the data streams that are relevant to the query evaluation.…”

Section: Introductionmentioning

confidence: 99%

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Divide, Compress and Conquer: Querying XML via Partitioned Path-Based Compressed Data Blocks

Lau

Zhou

2007

World Wide Web

Self Cite

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We propose a novel Partition Path-Based (PPB) grouping strategy to store compressed XML data in a stream of blocks. In addition, we employ a minimal indexing scheme called Block Statistic Signature (BSS) on the compressed data, which is a simple but effective technique to support evaluation of selection and aggregate XPath queries of the compressed data. We present a formal analysis and empirical study of these techniques. The BSS indexing is first extended into effective Cluster Statistic Signature (CSS) and Multiple-Cluster Statistic Signature (MSS) indexing by establishing more layers of indexes. We analyze how the response time is affected by various parameters involved in our compression strategy such as the data stream block size, the number of cluster layers, and the query selectivity. We also gain further insight about the compression and querying performance by studying the optimal block size in a stream, which leads to the minimum processing cost for queries. The cost model analysis provides a solid foundation for predicting the querying performance. Finally, we demonstrate that our PPB grouping and indexing strategies are not only efficient enough to support path-based selection and aggregate queries of the compressed XML data, but they also require relatively low computation time and storage space when compared with other state-of-the-art compression strategies.

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Effective asymmetric XML compression

2007

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The innate verbosity of the extensible markup language (XML) remains one of its main weaknesses, especially when large documents are concerned. This problem can be solved with the aid of dedicated XML compression algorithms. In this work, we describe XML word‐replacing transform (XML‐WRT), a fast and fully reversible XML transform, which, when combined with generally used LZ77‐style compression algorithms, allows to attain high compression ratios, comparable to those achieved by the current state‐of‐the‐art XML compressors. The resulting compression scheme is asymmetric in the sense that its decoder is much faster than the coder. This is a desirable practical property, as in many XML applications data are read much more often than written. The key features of the transform are dictionary‐based encoding of both document structure and content, separation of different content types into multiple streams, and dedicated encoding of specific patterns, including numbers and dates. The test results show that the proposed transform improves the XML compression efficiency of general‐purpose compressors on average by 35% in case of gzip, and 17% in case of LZMA. Compared with the current state‐of‐the‐art SCMPPM algorithm, XML‐WRT with LZMA attains over 2% better compression ratio, while being 55% faster. Copyright © 2007 John Wiley & Sons, Ltd.

show abstract

XCQ: A queriable XML compression system

Cited by 45 publications

References 20 publications

Efficient XML Usage within Wireless Sensor Networks

Efficient XML Usage within Wireless Sensor Networks

Divide, Compress and Conquer: Querying XML via Partitioned Path-Based Compressed Data Blocks

Effective asymmetric XML compression

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