We call these databases, ontologybased databases obdbs, and ontologybased data denotes those data that represent ontology individuals i. Ontologies are data description frameworks, usually formulated in languages that are readily available to end users. Ontologybased data access, query answering, query rewriting. The ontology is connected to external relational data management or data federation systems through a mapping establishing a semantic relation between sql queries issued over the underlying databases. Ontology based data access obda 8 is a novel paradigm that is similar in spirit to virtual data integration, but relies on the idea of replacing the global schema by an explicit formal representation of the domain of interest. Also, less manual mistakes can occur because this approach will minimize the manual interference in the integration process. The combined approach to ontologybased data access r. It extends the paradigm of ontologybased data access obda 11 to temporal and streaming data. Big data management is no longer an issue for large enterprises only. The developed ontologybased data access system, described. Its especially good when the relationships are complex and the information set is large and incomplete. A short course roman kontchakov 1, mariano rodr guezmuro2 and michael zakharyaschev 1 department of computer science and information systems. Today, enterprises have to handle business data and. It is one of the multiple data integration approaches and may be classified as globalasview gav.
The main idea of obda query answering is to represent the knowledge of the domain of interest in a declarative knowledge, aka ontology, and access the data via a highlevel query that refers to the ontologys vocabulary, aka signature. The objectives of this work are to investigate, how ontology based data access can be applied to existing software systems in order to increase the degree of separation between user interfaces and application logic. Ontologybased system development for medical database access. The ontop framework for ontology based data access. The ontology introduces incompleteness of knowledge, and we. Ontologybased data integration involves the use of ontologys to effectively combine data or information from multiple heterogeneous sources. D2rq 73,127, r2o 128, r2rml 128129 and on top 1 provide a set. The ontologybased data access obda paradigm aims at mitigating this phenomenon by providing to the users of the system a unified and shared conceptual view of the domain of interest ontology. Ontologybased data access obda 8 is a novel paradigm that is similar in spirit to virtual data integration, but relies on the idea of replacing the global schema by an explicit formal representation. Ontologybased data access obda outline 1 querying relational databases 2 rdf and other semantic web standards 3 ontologybased data access 4 optique platform 5 conclusion benjamin cogrel free.
School on technology and science for information and communication rome, june 15. Ontology based data access in statoil sciencedirect. A major issue in obda concerns the design of a specication and the management of its evolution. Mapping repair in ontologybased data access evolving systems. Ontology based data access obda is a prominent approach to query databases which uses an ontology to expose data in a conceptually clear manner by abstracting away from the technical. Ontologybased system development for medical database. To access data, users can specify sparql queries over the ontology and exploit mastros query answering services. Zakharyaschev2 1 department of informatics, university of oslo 2 department of computer science. Especially neat is the query mechanism in a good ontology database it intelligently uses the schema ontology such as any class hierarchies to return answers that would not be found otherwise. As we will show in section 4, after we load erp data into the nemo. In the obda paradigm, an ontology defines a highlevel global schema of. Usually, the conceptual layer is expressed in the form of an rdfs 10 or owl 15 ontology, and the data is stored in relational databases.
Introduction in this paper we present mastro, a tool for ontologybased data access developed at the university of. Ontologybased data access obda outline 1 querying relational databases 2 rdf and other semantic web standards 3 ontologybased data access 4 optique platform 5 conclusion benjamin cogrel free university of bozenbolzano obdaontop 26082016 143. Ruberti sapienza universit a di roma, italy lecture for course on the great ideas in ict ed. Ontologybased data access obda, aka ontologybased query answering obqa.
The statements above the line are assumed to be true, in which case the statement below the line. Ontologybased data access obda has gained attention in recent years for providing access to large volumes of data by using ontologies as a conceptual layer and exploring their ability to describe. In aberowl, following the ontologybased data access paradigm 6,7, we specify the features of the relevant information on the ontology and knowledge level, and retrieve named classes in ontologies satisfying these condition using an automated reasoner, i. Ontologybased data access obda is regarded as a key ingredient of the new generation of information systems. Anobda specicationis constituted by an ontology, usually a descrip. Ontologybased geospatial data query and integration. Creating linked data from relational databases nikolaos konstantinou dimitriosemmanuel spanos materializing the web of linked data. In this paper, we propose one such a fragment, in fact the largest frag. Ontology based data access obda outline 1 querying relational databases 2 rdf and other semantic web standards 3 ontology based data access 4 optique platform 5 conclusion benjamin cogrel free university of bozenbolzano obdaontop 26082016 143. Ontologybased data access obda, for short is a seman tic technology that has. We report on our experience in ontologybased data access to the.
In contrast, ontology based big data management will be based on semantic technologies, which will enable enterprises to integrate and manage data with a high degree of automation. Since the mid 2000s, ontologybased data access obda has become a popular approach to tackling this problem 27. Jul 25, 2012 in the last decade, the activity of the w3c consortium in the field of semantic web and development of standards of the ontology description languages induced a new activity wave in developing tools for systems of semantic access to databases and a new class of database systems, the socalled ontology based data access obda systems. Ontologybased geospatial data query and integration 373 and subproperty relations. Ontologybased data access ontologybased data access. The main idea of obda query answering is to represent the knowledge of the domain of interest.
Ontologybased access to information diego calvanese. The complexity of ontologybased data access with owl 2 ql and. To ensure a high performance of queries on top of these obdbs, e. The ontology based data access obda paradigm aims at mitigating this phenomenon by providing to the users of the system a unified and shared conceptual view of the domain of interest ontology. Implementation of a perfect rewriting algorithm for. Ontology based data access methods to teach students to. The ontop framework for ontology based data access 73 the. Ontology based data access obda is a prominent approach to data access in which an ontology is used to mediate between data consumers and data sources see a general diagram of obda in fig. This paper presents a novel approach for the ontologybased integration of heterogeneous medical data between clinical and research databases. Maurizio lenzerini ontology based data management semantic days 20 2053 framework for obdmquery answeringinconsistency toleranceother topics in obdmconclusions complexity of conjunctive query answering in dls. Ive used an ontology database in a real product and it was the only way to solve the problem. Systems free fulltext ontologybased big data management. Ontologybased data access obda 6, 11, 22 is regarded as a key ingredient.
Query answering in ontologybased data access systems the ontop framework for ontologybased data access d. Ontology based data integration involves the use of ontology s to effectively combine data or information from multiple heterogeneous sources. The ontology is connected to the data via mappings that allow to automatically. In relational databases, information is represented as tuples of values. Jan 28, 2015 in aberowl, following the ontologybased data access paradigm 6,7, we specify the features of the relevant information on the ontology and knowledge level, and retrieve named classes in ontologies satisfying these condition using an automated reasoner, i.
Pdf ontologybased data access obda is regarded as a key ingredient of the new generation of. Ontology based data access obdais the problem of access ing source databases through the mediation of a conceptual domain view, given in terms of an ontology poggi et al. This is done through mappings that connect the data in the database to the vocabulary of the ontology. Ontologybased data access, description logics, reasoning over ontologies 1. An ontology can be used to create a database that can. Ontology based access to exploration data at statoil. The terms in the conceptual layer are mapped to the data layer using mappings. Ontologybased data management 3 data is widespread into separate pieces of documentation that are often di cult to access and rarely conforming to common standards. Therefore, the requirements of the data exchange between the two system components have to be analyzed, and suitable obda 8. Ontologybased data access and integration in ontologybased data access and integration, we have to face the di culties of both settings. Ontology based access to information diego calvanese faculty of computer science master of science in computer science a. In this aspect, our method is closely related to 8 that also uses rdf ontology as a medium to provide integrated access to different relational databases.
In this aspect, our method is closely related to 8 that also uses rdf ontology as a medium to provide integrated access. The ontology is connected to external relational data management or data federation systems through a mapping establishing a semantic relation between sql queries issued over the underlying databases and elements of the ontology. The challenge comes in using the right database with the right structure to hold the information you need, while being able to access that data easily. In the obda paradigm, an ontology defines a highlevel global schema of already existing data sources and provides a vocabulary for user queries. It makes heavy use of abstraction by shifting the database.
A short course roman kontchakov 1, mariano rodr guezmuro2 and michael zakharyaschev 1 department of computer science and information systems, birkbeck, university of london, u. Techniques from partial evaluation of logic programs are adapted for unfolding. Introduction to ontology based data access optique. The optique platform is built on ontology based data access obda, a technology for providing uniform access to data stored in heterogeneous sources. Usually, the conceptual layer is expressed in the form of an rdfs 10 or. The ontology provides a single point of semantic data access for data consumers, and allows either to export data in a semantic format or to. So, obda resorts to a threelevel architecture, constituted by an ontology, the data sources, and the. Citeseerx document details isaac councill, lee giles, pradeep teregowda.
Ontologybased data integration between clinical and. Ontology based data access obda is considered as a suitable, flexible and powerful approach, being able to handle sophisticated data management tasks, by providing access to data, potentially stored in heterogeneous data sources, with the help of a semantic layer in the form of an ontology. Ontop of databases marianorodrguezmuro1,romankontchakov2,andmichaelzakharyaschev2 1 facultyofcomputerscience,freeuniversityofbozen. These queries are translated onthefly into sql queries by obda systems. This allows to access the data in the postgresql database using the mappings in the obda model. Ontology based data access obda is a prominent approach to query databases which uses an ontology to expose data in a conceptually clear manner by abstracting away from the technical schemalevel details of the underlying data. Ontop is an ontology based data access system allowing users to access a relational database through a conceptual layer provided by an ontology. Zakharyaschev2 1 department of informatics, university of oslo 2 department of computer science and information systems, birkbeck, university of london abstract. In fact, query answering can be delegated to a relational db engine.
Optimizing ontologybased data access diego calvanese and mariano rodriguezmuro krdb research centre for knowledge and data free university of bozenbolzano iso 15926 and semantic. Such a layer allows the client to have a conceptual view. In ontology based data access obda users pose sparql queries over an ontology that lies on top of relational datasources. Chapter 4 creating linked data from relational databases. That is, to the usual data layer of an information system we superimpose a conceptual layer to be exported to the client. Mapping repair in ontologybased data access evolving. This paper presents a novel approach for the ontology based integration of heterogeneous medical data between clinical and research databases. Ontology based data access obda has gained attention in recent years for providing access to large volumes of data by using ontologies as a conceptual layer and exploring their ability to describe domains and deal with data incompleteness.
Implementation of a perfect rewriting algorithm for ontology. Ontology based data management 3 data is widespread into separate pieces of documentation that are often di cult to access and rarely conforming to common standards. Maurizio lenzerini ontologybased data management semantic days 20 2153. Ontology based data access obda is considered as a suitable, flexible and powerful approach, being able to handle sophisticated data management tasks, by providing access to data, potentially stored in. Ontology based data access obda is regarded as a key ingredient of the new generation of information systems. It is one of the multiple data integration approaches. Ontologybased access to information knowledge bases. The developed ontology based data access system, described in this paper, provides a tool to store, manage and use definitions of common terminology and their mappings to the database. We call such a databaseanontologydatabase,whichisanontologybased,semanticdatabase model. We present the architecture and technologies underpinning the obda system ontop and taking full advantage of storing data in relational databases. Ontology based data access theory and practice guohui xiao.
In the last decade, the activity of the w3c consortium in the field of semantic web and development of standards of the ontology description languages induced a new activity wave in. Zakharyaschev1 1department of cs and information systems 2fachbereich. Ontology based access to information 1 introduction to ontology based access to information 1 introduction to ontologies 2 ontology languages 2 description logics and the dl. Databases, with numerous papers published in top cs jour nals including aij. Ontologybased data access obda is a new paradigm, based on the use of. Optique is financed by the seventh framework program fp7. The ontop system 40 is an example for an ontologybased data access obda system, where a global schema is defined as an owl2 ql ontology, and the source schemas are mapped to the global schema. The ontology and the corresponding mappings to the data sources provide a common ground for the documentation of all the data in the organisation, with obvious ad.