Ontologybased access to information diego calvanese. Its especially good when the relationships are complex and the information set is large and incomplete. 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. It makes heavy use of abstraction by shifting the database. Maurizio lenzerini ontologybased data management semantic days 20 2153. 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. 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. A short course roman kontchakov 1, mariano rodr guezmuro2 and michael zakharyaschev 1 department of computer science and information systems. 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. Introduction in this paper we present mastro, a tool for ontologybased data access developed at the university of. 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. An ontology can be used to create a database that can. It is one of the multiple data integration approaches. Ontology based data access methods to teach students to.
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. Ontologybased data access obda is regarded as a key ingredient of the new generation of information systems. Ontologybased data access and integration in ontologybased data access and integration, we have to face the di culties of both settings. Usually, the conceptual layer is expressed in the form of an rdfs 10 or. In the obda paradigm, an ontology defines a highlevel global schema of already existing data sources and provides a vocabulary for user queries. This paper presents a novel approach for the ontologybased integration of heterogeneous medical data between clinical and research databases.
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. Ontologybased data access obda, aka ontologybased query answering obqa. Ontop of databases marianorodrguezmuro1,romankontchakov2,andmichaelzakharyaschev2 1 facultyofcomputerscience,freeuniversityofbozen. This allows to access the data in the postgresql database using the mappings in the obda model. 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. It is one of the multiple data integration approaches and may be classified as globalasview gav. To ensure a high performance of queries on top of these obdbs, e. A major issue in obda concerns the design of a specication and the management of its evolution. 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. 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. Mapping repair in ontologybased data access evolving. We call such a databaseanontologydatabase,whichisanontologybased,semanticdatabase model.
Ontologybased system development for medical database. 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. D2rq 73,127, r2o 128, r2rml 128129 and on top 1 provide a set. 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. The main idea of obda query answering is to represent the knowledge of the domain of interest.
Ive used an ontology database in a real product and it was the only way to solve the problem. Mapping repair in ontologybased data access evolving systems. Introduction to ontology based data access optique. Ontology based data access obda is regarded as a key ingredient of the new generation of information systems. 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. Anobda specicationis constituted by an ontology, usually a descrip. Zakharyaschev2 1 department of informatics, university of oslo 2 department of computer science. Ontologybased system development for medical database access. In this aspect, our method is closely related to 8 that also uses rdf ontology as a medium to provide integrated access. In the obda paradigm, an ontology defines a highlevel global schema of. To access data, users can specify sparql queries over the ontology and exploit mastros query answering services. In fact, query answering can be delegated to a relational db engine.
Big data management is no longer an issue for large enterprises only. 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. Today, enterprises have to handle business data and. Optique is financed by the seventh framework program fp7. Pdf ontologybased data access obda is regarded as a key ingredient of the new generation of. 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. This is done through mappings that connect the data in the database to the vocabulary of the ontology. Ontologybased data access, query answering, query rewriting. Chapter 4 creating linked data from relational databases. In relational databases, information is represented as tuples of values. Creating linked data from relational databases nikolaos konstantinou dimitriosemmanuel spanos materializing the web of linked data. That is, to the usual data layer of an information system we superimpose a conceptual layer to be exported to the client. Ontologybased data integration between clinical and research. Ontology based access to exploration data at statoil.
We report on our experience in ontologybased data access to the. The ontop framework for ontology based data access. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Oct 20, 2017 the combined approach to ontology based data access introduction to ontology based data access labels. Ontology based access to information diego calvanese faculty of computer science master of science in computer science a. Implementation of a perfect rewriting algorithm for. In this paper, we propose one such a fragment, in fact the largest frag. 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 geospatial data query and integration. We call these databases, ontologybased databases obdbs, and ontologybased data denotes those data that represent ontology individuals i. Zakharyaschev2 1 department of informatics, university of oslo 2 department of computer science and information systems, birkbeck, university of london abstract. It makes heavy use of abstraction by shifting the databasecentered, technical thinking based on tables, columns and rows to a focus on medical concepts and their relations. The ontology introduces incompleteness of knowledge, and we. 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. 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. As we will show in section 4, after we load erp data into the nemo. Ontologybased data access ontologybased data access. School on technology and science for information and communication rome, june 15. 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.
Query answering in ontologybased data access systems the ontop framework for ontologybased data access d. 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. The ontop framework for ontology based data access 73 the. 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. We present the architecture and technologies underpinning the obda system ontop and taking full advantage of storing data in relational databases. Implementation of a perfect rewriting algorithm for ontology. It extends the paradigm of ontologybased data access obda 11 to temporal and streaming data. Ruberti sapienza universit a di roma, italy lecture for course on the great ideas in ict ed. Optimizing ontologybased data access diego calvanese and mariano rodriguezmuro krdb research centre for knowledge and data free university of bozenbolzano iso 15926 and semantic. The optique platform is built on ontology based data access obda, a technology for providing uniform access to data stored in heterogeneous sources. The terms in the conceptual layer are mapped to the data layer using mappings. 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.
These queries are translated onthefly into sql queries by obda systems. Ontologybased geospatial data query and integration 373 and subproperty relations. 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. The complexity of ontologybased data access with owl 2 ql and. Therefore, the requirements of the data exchange between the two system components have to be analyzed, and suitable obda 8. Ontology based data access theory and practice guohui xiao. In ontology based data access obda users pose sparql queries over an ontology that lies on top of relational datasources. The developed ontologybased data access system, described. 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. Ontologybased data integration involves the use of ontologys to effectively combine data or information from multiple heterogeneous sources. So, obda resorts to a threelevel architecture, constituted by an ontology, the data sources, and the. 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.
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. 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. 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. Ontologies are data description frameworks, usually formulated in languages that are readily available to end users. 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. Ontologybased data access obda is a new paradigm, based on the use of. Ontologybased data access obda 6, 11, 22 is regarded as a key ingredient. 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. Ontologybased data access obdais the problem of accessing source databases through the mediation of a conceptual domain view, given in terms of an ontologypoggi et al. Ontologybased data access, description logics, reasoning over ontologies 1. This paper presents a novel approach for the ontology based integration of heterogeneous medical data between clinical and research databases. Ontology based data access in statoil sciencedirect. 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. 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.
The statements above the line are assumed to be true, in which case the statement below the line. 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. Ontologybased access to information knowledge bases. Since the mid 2000s, ontologybased data access obda has become a popular approach to tackling this problem 27. Databases, with numerous papers published in top cs jour nals including aij. 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. Ontop is an ontology based data access system allowing users to access a relational database through a conceptual layer provided by an ontology. The ontology is connected to the data via mappings that allow to automatically. 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. 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 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. Techniques from partial evaluation of logic programs are adapted for unfolding.
Ontologybased data integration between clinical and. Systems free fulltext ontologybased big data management. 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. Such a layer allows the client to have a conceptual view. 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. Ontology based data integration involves the use of ontology s to effectively combine data or information from multiple heterogeneous sources. We illustrate this approach for ontologies given in the dllite family of description logics and brie. Ontologybased data access obda, for short is a seman tic technology that has.
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