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Fédération de données semi-structurées avec XML

Abstract : In contrast to the traditional data, semi-structured data are irregular: data may be missed, different data types may be for the similar concepts, and if any the structure may not be well-known. One lacks actually predefined schemas to describe the data of the real world. It makes it difficult to integrate the data from different sources. We propose a mediator architecture entirely based on XML. The objective of the mediator architecture is to federate distributed and heterogeneous data sources. It relies on XQuery, the functional language that is designed to query across XML documents. The mediator parses the XQuery request, dispatch it to sources for evaluation and recompose results with additional query evaluation. Query evaluation must be done by making best use of data specificity to carry out an efficient optimization. We present the algebra XAlgebra based on the operators designed for XML. This algebra aims to construct execution plans for the evaluation of XQuery and processes tuples of tree structure. These execution plans must be evaluated by a cost model and one of them with the minimal cost will be selected. In this thesis, we define a cost model for semi-structured data that is designed for our algebra. Since the data sources (DBMS, Web server, search engine, etc.) may be very heterogeneous, they can have different capabilities of processing data, and their cost models may also be defined with different precision. So, in order to integrate such information in the mediation architecture, we have to know how to communicate the information between the mediator and the sources and to integrate them. To do this, we use XML-based languages such as XML-schema and MathML to export the metadata, cost formula and the definitions of source capabilities. The exported information is transferred by an application interface called XML/DBC. Finally, diverse optimizations specific to this mediator architecture must be considered. For this, we introduce a semantic cache based on the DBMS prototype that store natively and efficiently XML data.
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https://theses.hal.science/tel-00733510
Contributor : Tuyet-Tram Dang-Ngoc Connect in order to contact the contributor
Submitted on : Friday, December 28, 2012 - 10:48:47 PM
Last modification on : Wednesday, October 20, 2021 - 12:24:13 AM
Long-term archiving on: : Friday, March 29, 2013 - 3:48:14 AM

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  • HAL Id : tel-00733510, version 1

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Tuyet-Tram Dang-Ngoc. Fédération de données semi-structurées avec XML. Base de données [cs.DB]. Université de Versailles-Saint Quentin en Yvelines, 2003. Français. ⟨NNT : ⟩. ⟨tel-00733510⟩

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