Integrating and Exchanging XML Data Using Ontologies

Abstract

Abstract. While providing a uniform syntax and a semistructured data model, XML does not express semantics but only structure such as nesting information. In this paper, we consider the problem of data integration and interoperation of heterogeneous XML sources and use an ontology-based framework to address this problem at a semantic level. Ontologies are extensively used for domain knowledge representation, by virtue of their conceptualization of the domain, which carries explicit semantics. In our approach, the global ontology is expressed in RDF Schema (RDFS) and constructed using the global-as-view approach by merging individual local ontologies, which represent XML source schemas. We provide a formal model for the mappings between XML schemas and local RDFS ontologies and those between local ontologies and the global RDFS ontology. We consider two cases of query processing, specifically for data integration and for data interoperation. In the first case, the user poses an RDF query on the global ontology, which is answered using all the mapped XML sources. In the second case, a query is posed on a single source and then is mapped to the XML sources that are connected to that source. For each case, we discuss the problem of query containment and present an equivalent query rewriting algorithm for queries expressed in two languages: conjunctive RDQL and conjunctive XQuery.

Enabling Cross Constraint Satisfaction in RDF-Based Heterogeneous Database Integration

“…The process involves: i) the generation of a set of queries in terms of the local databases integrated in the system, ii) the storage of the partial results that these queries generate into an auxiliary database, and iii) the extraction of the final results from this database. The procedure of translating a global query into a set of local queries has been covered in many previous publications [6,7,9,10,11,12,14,15]. The approach exposed in this work does not differ from them in the essence of query translation.…”

“…The same idea can be found in [11], where Cali describes his system for performing semantic integration of heterogeneous sources. Xiao, in his description of his own approach for integration of heterogeneous XML sources [12], states that the partial results are "integrated (by using union) to produce the answer to q". Lehti, in his paper about integration of XML sources using OWL as global schema [13], mentions the necessity of defining join conditions when merging data from different sources.…”

A layered framework supporting personal information integration and application design for the semantic desktop

“…If the PIAs are seen a connected peers (i.e., service providers for a particular data access), A2A query processing is similar to that that occurs in peer-to-peer (P2P) systems [10,61,62]. The PIAs may exist in a single desktop or may be physically distributed across different desktops.…”

A Secure Mediator for Integrating Multiple Level Access Control Policies

“…Semantic Web languages such as RDF Schema (or RDFS) [4] and OWL [16] are particularly suited to represent the global information and to abstract from the particular data formats (relational, XML, etc.) or from the different schemas within the same format, thus addressing respectively problems of syntactic heterogeneity [6] and of structural (or schematic) heterogeneity [17].…”

“…In order to overcome syntactic, structural, and semantic heterogeneities, schemas can be integrated at a semantic level. For example, the problem of structural heterogeneities has been addressed in a previous approach [17], where a two-step integration framework is proposed. In the first step, the XML schemas are transformed into RDF schemas.…”