Database to Semantic Web Mapping Using RDF Query Languages

Abstract

Abstract. One of the main drawbacks of the Semantic Web is the lack of semantically rich data, since most of the information is still stored in relational databases. In this paper, we present an approach to map legacy data stored in relational databases into the Semantic Web using virtually any modern RDF query language, as long as it is closed within RDF. Consequently, a Semantic Web developer does not need to learn and adopt a new mapping language, but he may perform the mapping task using his preferred RDF query language. MotivationDespite the vision of a Semantic Web [6] and many efforts helping to realize it, the actual Semantic Web still lacks of enough semantic data. Most information is still modeled and stored in relational databases and thus out of reach for many Semantic Web applications. As a consequence, such applications need to create a corresponding mapping between the relational and the semantic models by themselves for being able to access relational data. Realizing this situation, some efforts have arisen to straighten out this deplorable situation. Most approaches translate relational data into a Semantic Web representation using a proprietary mapping language (cf. Section 2). In [19] we have introduced Relational.OWL, our technique to automatically transform relational data into a machine processable and understandable representation (cf. Section 3.1). Nevertheless, such a representation does not include real semantics, since it converts the schema of a database automatically into an ontology and the data items as its instances, i.e. the data is described as it was in the database. For many Semantic Web applications, this is a reasonable technique, since they are able to quickly access legacy data stored in a relational database using their own built-in functionality. However, such a representation could be inappropriate, if the data has to be processed for further reasoning tasks. In this paper we present how to map relational data into the Semantic Web using virtually any modern RDF query language, as long as the language is closed within RDF, i.e. it returns valid RDF graphs as query results. For this purpose, data and schema components of the original relational database are

Semantics-Preserving RDB2RDF Data Transformation Using Hierarchical Direct Mapping

“…Therefore, if x and y have the same URI, then G1 and G2 can be merged into one graph. Second, we prove (2). Assume that G1 and G2 can be merged into one graph, p is a property that has the same URI as p1 and p2, p = p1 = p2, G1 has only one triple t(x, p, o1), G2 has only one triple t(y, p, o2), and q(s, p, o) is a query function to find triples.…”

“…The transformation of relational databases (RDB) into resource-description-framework (RDF) data is a key information extraction method used to publish semantics web data [1][2][3]. In 1998, Tim Berners-Lee proposed the concept of mapping RDBs to the Semantic Web [4].…”

Ontology Based Data Access in Statoil

“…Finally, MIRROR, Ontop, Ultrawrap and AutoMap4OBDA are conformant to the OWL 2 QL, but they do not support profiling to the other sublanguages of OWL 2. As BootOX, systems like Automapper [77], Relational.OWL [86] and ROSEX [87] complement the automatically generated ontology with links to domain ontologies. However, none of these systems apply logic-based techniques to assess the consequences of such links to domain ontologies.…”

BootOX: Practical Mapping of RDBs to OWL 2

“…As BOOTOX, systems like Automapper [12], Relational.OWL [21] and ROSEX [11] complement the automatically generated ontology with links to domain ontologies. However, none of these systems apply logic-based techniques to assess the consequences of such links to domain ontologies.…”