Linked Data on the Web (LDOW2008) Workshop at the 17th International World Wide Web Conference Beijing, China, April 22, 2008 Christian Bizer Tom Heath Kingsley Idehen Tim Berners-Lee Freie Universität Berlin Talis OpenLink Software W3C Germany United Kingdom USA USA chris@bizer.de tom.heath@talis.com kidehen@openlinksw.com timbl@w3.org ABSTRACT hypertext links, the Web of Data can be crawled by following The Web is increasingly understood as a global information space RDF links. Working on the crawled data, search engines can consisting not just of linked documents, but also of Linked Data. provide sophisticated query capabilities, similar to those provided More than just a vision, the resulting Web of Data has been by conventional relational databases. Because the query results brought into being by the maturing of the Semantic Web themselves are structured data, not just links to HTML pages, technology stack, and by the publication of an increasing number they can be immediately processed, thus enabling a new class of of data sets according to the principles of Linked Data. applications based on the Web of Data. The Linked Data on the Web (LDOW2008) workshop brings The glue that holds together the traditional document Web is the together researchers and practitioners working on all aspects of hypertext links between HTML pages. The glue of the data web is Linked Data. The workshop provides a forum to present the state RDF links. An RDF link simply states that one piece of data has of the art in the field and to discuss ongoing and future research some kind of relationship to another piece of data. These challenges. In this workshop summary we will outline the relationships can have different types. For instance, an RDF link technical context in which Linked Data is situated, describe that connects data about people can state that two people know developments in the past year through initiatives such as the each other; an RDF link that connects information about a person Linking Open Data community project, and look ahead to the with information about publications in a bibliographic database workshop itself. might state that a person is the author of a specific paper. Categories and Subject Descriptors 2. THE LINKING OPEN DATA PROJECT Evidence of the emergence of a Web of Data comes from the H.3.5. [Information Storage and Retrieval]: Online Information Linking Open Data project1, a grassroots community effort Services – Data sharing. H.3.5. [Information Storage and founded in February 2007 and supported by the W3C Semantic Retrieval]: Online Information Services – Web-based services. Web Education and Outreach Working Group2. The aim of the project is to identify data sets that are available under open 1. THE WEB OF DATA licenses, re-publish these in RDF on the Web and interlink them Linked Data is about employing the Resource Description with each other. Framework (RDF) and the Hypertext Transfer Protocol (HTTP) to publish structured data on the Web and to connect data between During 2007, the size of the Web of Data that directly stems from different data sources, effectively allowing data in one data source this community effort has grown to over two billion RDF triples, to be linked to data in another data source. originating from data sets in diverse domains such as geographic information, census information, people, companies, online The principles of Linked Data were first outlined by Berners-Lee communities, human languages, scientific publications, films, in 2006 [1], and provide broad guidance upon which data music, books and reviews3. These data sets are interlinked by publishers have begun to realize the Web of Data. This guidance around three million RDF links. has been extended by technical documents such as [2][3] that capture best practices emerging from the Linked Data community An indication of the range and scale of the Linking Open Data and provide recipes on which publishing systems can be based. "cloud" is provided in Figure 1. As this diagram shows, key interlinking hubs are sites such as DBpedia4 and Geonames5. The Web of Data can be accessed using Linked Data browsers, DBpedia extracts RDF triples from the "Infoboxes" commonly just as the traditional Web of documents is accessed using HTML seen on the right hand side of Wikipedia articles, and makes these browsers. However, instead of following links between HTML available on the Web in RDF to be crawled or queried with pages, Linked Data browsers enable users to navigate between different data sources by following RDF links. This allows the user to start with one data source and then move through a 1 http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/ potentially endless Web of data sources connected by RDF links. LinkingOpenData Just as the traditional document Web can be crawled by following 2 http://www.w3.org/2001/sw/sweo/ 3 http://richard.cyganiak.de/2007/10/lod/ Copyright is held by the author/owner(s). 4 LDOW2008, April 22, 2008, Beijing, China. http://dbpedia.org/About 5 http://www.geonames.org/ Figure 1. The Linking Open Data "cloud", February 2008 SPARQL. Geonames in turn provides RDF descriptions of innovative applications that consume Linked Data, and shape millions of geographical locations worldwide. DBpedia and the agenda and identify upcoming research issues for the next Geo-names provide URIs (and RDF descriptions) for many of development stage of the Web of Data. the things in the world to which we want to refer. As these URIs The program of papers to be presented at the workshop are reused within other data sets, DBpedia and Geonames demonstrates ongoing innovation not just in populating the Web develop into hubs to which an increasing number of other data of data, but in developing applications that exploit this sets are connected, thereby increasing the potential for network ecosystem for end users, and in advancing conceptual and effects. architectural issues related to the field. In total 37 papers and In addition to publishing and interlinking data sets, there is also demos were submitted for review, of which 23 were accepted ongoing work within the community project on Linked Data for presentation at the workshop and inclusion in the browsers, Linked Data crawlers, Web of Data search engines proceedings. and other applications that consume Linked Data from the Web. We would like to extend our sincere thanks to the LDOW2008 Examples of Linked Data browsers6 are Tabulator, Disco, the Program Committee for the efforts they expended in reviewing OpenLink data browser and the Zitgist browser. Examples of the submitted papers, and to the WWW2008 organizers for their Web of Data search engines7 and lookup indexes are Falcons, support of the workshop. For more information about the Sindice, Swoogle and Watson. These services enable humans workshop program please refer to the workshop website: and machines to locate and query Linked Data that has been published across the Web. http://events.linkeddata.org/ldow2008/ 3. THE LDOW2008 WORKSHOP 4. REFERENCES The goal of the workshop is to provide a forum for the Linked [1] Berners-Lee, T. Linked Data. 2006. Data community, in which participants can present and discuss http://www.w3.org/DesignIssues/LinkedData.html approaches to publishing Linked Data on the Web, showcase [2] Bizer, C., Cyganiak, R., Heath, T. How to Publish Linked Data on the Web. 2007. http://www4.wiwiss.fu- 6 http://esw.w3.org/topic/TaskForces/CommunityProjects/ berlin.de/bizer/pub/LinkedDataTutorial/ LinkingOpenData/SemWebClients [3] Sauermann, L., Cyganiak, R., Ayers, D., Völkel, M. Cool 7 URIs for the Semantic Web. 2007. http://esw.w3.org/topic/TaskForces/CommunityProjects/ LinkingOpenData/SemanticWebSearchEngines http://www.w3.org/TR/cooluris/