The SPARQL2XQuery interoperability framework Utilizing Schema Mapping, Schema Transformation and Query Translation to Integrate XML and the Semantic Web

• Published in: World wide web (Bussum) Vol. 18; no. 2; pp. 403 - 490
• Main Authors: Bikakis, Nikos, Tsinaraki, Chrisa, Stavrakantonakis, Ioannis, Gioldasis, Nektarios, Christodoulakis, Stavros
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2015
• Subjects: Automation; Computer Science; Database Management; Extensible Markup Language; Information Systems Applications (incl.Internet); Interoperability; Mapping; Operating Systems; Query processing; Semantics; Translations; XML; Integration; Linked data; Data transformation; SPARQL 1.1; Semantic web; SPARQL endpoint; SPARQL to XQuery; Query translation; Schema mappings; Schema transformation; OWL 2; XML data; XML schema 1.1; XML Schema to OWL; SPARQL update
• ISSN: 1386-145X; 1573-1413
• DOI: 10.1007/s11280-013-0257-x

In the context of the emergent Web of Data , a large number of organizations, institutes and companies (e.g., DBpedia , Data.gov , GeoNames , PubMed ) adopt the Linked Data practices. Utilizing the Semantic Web ( SW ) technologies, they publish their data and offer SPARQL endpoints (i.e., SPARQL-based search services). On the other hand, the dominant standard for information exchange in the Web today is XML. Additionally, many international standards (e.g., Dublin Core , MPEG-7 , METS , TEI , IEEE LOM ) in several domains (e.g., Digital Libraries, GIS, Multimedia, e-Learning) have been expressed in XML Schema. The aforementioned have led to an increasing emphasis on XML data, accessed using the XQuery query language. The SW and XML worlds and their developed infrastructures are based on different data models, semantics and query languages. Thus, it is crucial to develop interoperability mechanisms that allow the Web of Data users to access XML datasets, using SPARQL, from their own working environments. It is unrealistic to expect that all the existing legacy data (e.g., Relational, XML, etc.) will be transformed into SW data. Therefore, publishing legacy data as Linked Data and providing SPARQL endpoints over them has become a major research challenge. In this direction, we introduce the SPARQL2XQuery Framework which creates an interoperable environment, where SPARQL queries are automatically translated to XQuery queries, in order to access XML data across the Web. The SPARQL2XQuery Framework provides a mapping model for the expression of OWL–RDF/S to XML Schema mappings as well as a method for SPARQL to XQuery translation. To this end, our Framework supports both manual and automatic mapping specification between ontologies and XML Schemas. In the automatic mapping specification scenario, the SPARQL2XQuery exploits the XS2OWL component which transforms XML Schemas into OWL ontologies. Finally, extensive experiments have been conducted in order to evaluate the schema transformation, mapping generation, query translation and query evaluation efficiency, using both real and synthetic datasets.