Introduction to LOD2

Abstract

Abstract. In this introductory chapter we give a brief overview on the Linked Data concept, the Linked Data lifecycle as well as the LOD2 Stack -an integrated distribution of aligned tools which support the whole life cycle of Linked Data from extraction, authoring/creation via enrichment, interlinking, fusing to maintenance. The stack is designed to be versatile; for all functionality we define clear interfaces, which enable the plugging in of alternative third-party implementations. The architecture of the LOD2 Stack is based on three pillars: (1) Software integration and deployment using the Debian packaging system. (2) Use of a central SPARQL endpoint and standardized vocabularies for knowledge base access and integration between the different tools of the LOD2 Stack. (3) Integration of the LOD2 Stack user interfaces based on REST enabled Web Applications. These three pillars comprise the methodological and technological framework for integrating the very heterogeneous LOD2 Stack components into a consistent framework.The Semantic Web activity has gained momentum with the widespread publishing of structured data as RDF. The Linked Data paradigm has therefore evolved from a practical research idea into a very promising candidate for addressing one of the biggest challenges in the area of intelligent information management: the exploitation of the Web as a platform for data and information integration as well as for search and querying. Just as we publish unstructured textual information on the Web as HTML pages and search such information by using keyword-based search engines, we are already able to easily publish structured information, reliably interlink this information with other data published on the Web and search the resulting data space by using more expressive querying beyond simple keyword searches. The Linked Data paradigm has evolved as a powerful enabler for the transition of the current document-oriented Web into a Web of interlinked Data and, ultimately, into the Semantic Web. The term Linked Data here refers to a set of best practices for publishing and connecting structured data on the Web. These best practices have been adopted by an increasing number of data providers over the past three years, leading to the creation of a global data space that contains many billions of assertions -the Web of Linked Data (cf. Fig. 1).In that context LOD2 targets a number of research challenges: improve coherence and quality of data published on the Web, close the performance gap between relational and RDF data management, establish trust on the Linked Data Web and generally lower the entrance barrier for data publishers and users. The LOD2 project tackles these challenges by developing:• enterprise-ready tools and methodologies for exposing and managing very large amounts of structured information on the Data Web.• a testbed and bootstrap network of high-quality multi-domain, multi-lingual ontologies from sources such as Wikipedia and OpenStreetMap.• algorithms based on machine learning for automatically i...

Experiences with creating a Precision Dairy Farming Ontology (DFO) and a Knowledge Graph for the Data Integration Platform in agriOpenLink

“…Semantic Web technologies have reached considerable maturity, and have been already successfully demonstrated in different sectors, such as tourism, e-health, production and agriculture (Auer 2014). The World Wide Web Consortium (W3C) offers Semantic Web standards for representing data and knowledge in uniquely referenceable, linked data format with high expressivity, thus accelerating the development of expert services and opening the sector for new data and knowledge providers (Cardoso 2007).…”

“…The available Semantic Web stack include tools for 1) extraction of structured data from unstructured sources, such as text, 2) linked data authoring or creation via "triplification", enrichment, interlinking and fusing and 3) data maintenance in a semantic repository -the triplestore (Auer 2014).…”

“…The semantic technology has been tested in applications requiring knowledge management in numerous domains such as open government solutions, but also for corporate information systems in eHealth, tourism, media publishing, smart energy (Auer, 2014). Within the agricultural domain the Semantic Web approach already inspired a number of solutions in the research spectrum, e.g., (Eckartz et al 2013;Chaplinskyy et al 2013;Gao 2005;Athanasiadis et al 2009;Grimnes et al 2012) and is also embraced by the Food and Agriculture Organization of the United Nations (FAO; http://aims.fao.org) in their global initiatives for agricultural information management systems (AIMS), AGROVOC vocabulary, and agricultural ontology service (Lauser et al 2006 Two problems in the data integration that have been identified as related to the ADIS/ADED based exchange and have been described previously in Section 2.1, can be efficiently solved by the Semantic Web approach.…”

Microblog topic identification using Linked Open Data

“…Linked Open Data ( lod ) refers to the data published using Linked Data principles under an open license. It is an up-to-date collection of interrelated web resources that spans all domains of human interests, such as music, sports, news, and life sciences [ 75 , 76 ]. lod contains 1,255 datasets with 16,174 links among them (as of May 2020) [ 77 ].…”

Linked Open Data Life Cycle

“…Those models are concerned about the data and metadata structures and reaching to an appropriate quality level [9]. Supporting the data through the linked data life cycle is a challenging task whether the support is through developing research approaches, standards, technology or tools [10]. There are only a few production-leveal quality tools available for modelling or publishing linked open data such as LOD2 Stack [9].…”