Auer Sören - Linked open data - creating knowledge out of interlinked data: results of the LOD2 Project

The Author(s) 2014

Sren Auer 1

(1)

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. ).

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: The LOD2 project integrates and syndicates linked data with large-scale, existing applications and showcases the benefits in the three application scenarios publishing, corporate data intranets and Open Government Data.

The main result of LOD2 is 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 LOD2 Stack comprises new and substantially extended existing tools from the LOD2 partners and third parties. The major components of the LOD2 Stack are open-source in order to facilitate wide deployment and scale to knowledge bases with billions of triples and large numbers of concurrent users. Through an agile, iterative software development approach, we aim at ensuring that the stack fulfills a broad set of user requirements and thus facilitates the transition to a Web of Data. The stack is designed to be versatile; for all functionality we define clear interfaces, which enable the plugging in of alternative third-party implementations. We also plan a stack configurer, which enables potential users to create their own personalized version of the LOD2 Stack, which contains only those functions relevant for their usage scenario. In order to fulfill these requirements, the architecture of the LOD2 Stack is based on three pillars: These three pillars comprise the methodological and technological framework for integrating the very heterogeneous LOD2 Stack components into a consistent framework. This chapter is structured as follows: After briefly introducing the linked data life-cycle in Sect..