XQuery-based query engine system

Abstract

The invention discloses an XQuery-based query engine system comprising a mediator and a wrapper. The mediator comprises a lexical analysis module, a grammar analysis module, a normalization module, a query decomposition module and a result processing module, wherein the lexical analysis module breaks the XQuery statement into a token carrying an attribute; the grammar analysis module organizes the token into an abstract syntax tree based on an XQuery grammar specification; the normalization module arranges the syntax tree to form a well-formed syntax tree; the query decomposition module traverses the syntax tree, generates a subquery with respect to an underlaying data source and transfers corresponding wrappers; and the result processing module receives a query result transmitted by the wrapper and returns the query result to a user in the form of XML. The wrapper comprises a relation-type data source wrapper and an XML data source wrapper, and receives the XQuery subquery which is transmitted from the mediator and converted into query language supported by the data source for underlaying data source query, and the final result is reconstructed into XML format and transmitted to the result processing module. The invention improves the query efficiency, ensures favorable structure of the query clause constructed by normalization of the abstract syntax tree and enhances the readability.

Description

Technical field [0001] The present invention involves the field of data integration technology, which specializes in a data integration platform with XML as a data model and XQuery as a query language. Background technique [0002] The development of the information society has led to the emergence of massive heterogeneous data, making data sharing a bottleneck.As XML technology becomes the standard for data exchange, the data integration platform with XML as a data -type type has attracted people's attention. [0003] The more representative query language for XML includes: [0004] 1) The XSL scalable style table language proposed by W3C is dedicated to processing XML documents, but only read the content of the document, and cannot be changed or edited on the document; [0005] 2) XQL language, which is used to locate and filter the symbols of elements and texts in XML documents, but the scope of application is limited to XML documents, so it can be scalability; [0006] 3) Th...

AI Technical Summary

Problems solved by technology

On the data integration platform based on the intermediary model with XML as the data model and XQuery as the query statement, the XQuery global query is decomposed into subqueries for each data source by the intermediary, and the corresponding wrapper is called to implement the underlying data source. Query, receive query results, reorganize the query results into XML data and deliver them to users, which can solve the query problem of heterogeneous data sources in data integration

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