The SPARQL-RW framework: mapping modeling and query rewriting for ontology based mediatorsThe SPARQL-RW framework: mapping modeling and query rewriting for ontology based mediators Μεταπτυχιακή Διατριβή Master Thesis 2014-05-082014enThe Web of Data is an open environment consisting of heterogeneous, distributed and highly structured information sources. Uniform information access in this kind of setting is of major importance for data consumer applications and end users. To this end, ontology based mediator systems supporting transparent query access over federated data sources are considered essential. In this thesis we present SPARQL-RW, a Framework supporting mapping modeling and query rewriting in the context of ontology based mediator architectures. SPARQL-RW provides a formal model for describing mappings between ontology schemas, as well as a generic method for SPARQL 1.1 query rewriting, with respect to a set of predefined ontology mappings and data source endpoints. The mapping model supports a set of rich and flexible mapping types based on Description Logic semantics, as well as notable mapping formalisms, including Global-As-View (GAV), Local-As-View (LAV), and Global-and-Local-As-View (GLAV). Additionally, it defines a mapping language capable of representing all the supported types of inter-schema correspondences. The Framework provides functionality for performing mapping inference and for identifying inconsistencies in a given set of mappings and ontology schemas. Regarding query rewriting, the proposed algorithms are proved to provide semantics preserving queries with respect to the GAV mapping types supported by the model. The reformulated queries can be executed directly on any SPARQL federated query engine, or exploited as logical query plans by any ontology based mediator system. SPARQL-RW has been implemented, formally evaluated and tested in a prototype mediator system integrating several data providers from the biodiversity community along with DBpedia.A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Electronic & Computer Engineering at the School of Electronic & Computer Engineering - Technical University of Crete.Μεταπτυχιακή Διατριβή που υποβλήθηκε στη σχολή ΗΜΜΥ του Πολ. Κρήτης για την πλήρωση προϋποθέσεων λήψης του Μεταπτυχιακού Διπλώματος Ειδίκευσης.http://creativecommons.org/licenses/by-nc/4.0/Πολυτεχνείο Κρήτης::Σχολή Ηλεκτρονικών Μηχανικών και Μηχανικών ΥπολογιστώνMakris_Konstantinos_Msc_2014.pdfChania [Greece]Library of TUC2014-05-08application/pdf8.6 MBfree Makris Konstantinos Μακρης Κωνσταντινος Christodoulakis Stavros Χριστοδουλακης Σταυρος Deligiannakis Antonios Δεληγιαννακης Αντωνιος Lagoudakis Michael Λαγουδακης Μιχαηλ Πολυτεχνείο Κρήτης Technical University of Crete Σημασιολογικός Ιστός Ενοποίηση δεδομένων SPARQL OWL Semantic Web Data integration