SAMT09 - Web of Data Tutorial - Part 1

Web of Data in the Context of Multimedia Part 1: Linked Open Data: Vision, Concepts and Technologies Bernhard Haslhofer, Bernhard Schandl, Andreas Langegger, Wolfgang Halb, Tobias Bürger 1 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Agenda   Introduction   Multimedia Interlinking   Producing Linked Data   Multimedia Annotations   Existing Data Sets   Enriching Personal Media Collections   Linking Data   Consuming Linked Data 2 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Introduction: The Web of Data Vision 3 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

4 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data Vision   There is lots of data about the movie “The Shining” available on the Web… Genre: Horror/Thriller Release Date: 23 May 1980 (USA) Title: The Shining Distributors: Warner Bros. Pictures Distribution Running Time: 146 min (original), 144 min (cut), 120min (European cut) Starring: Jack Nicholson, Shelly Produced by: Stanley Kubrick Duvall, Danny Lloyd, … 8 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data Vision   …but only in a human-readable representation (HTML)   Difficult to access these data by applications, unless   they start parsing HTML representations (difficult, erroneous)   they use data source specific APIs (e.g., Web Services), if there are any   Metadata about (multimedia) resources are still locked in closed data silos 9 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

DB DB DB DB 10 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data Vision   The Web is successful because it provides   Uniform encoding (HTML)   Uniform addressing (URI)   Uniform transportation (HTTP) for the exchange of documents.   Why not apply the same mechanism to the underlying data? 11 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data Vision   The Web of Data vision is to use the Web to provide access not only to documents but also to the underlying data 12 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

The Linked Data Principles   Use URIs as names for things   Use HTTP URIs so that people can look up those names   When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)   Include links to other URIs, so that they can discover more things 13 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

The Enabling Technologies 14 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

URI   Uniform Resource Identifiers (URI) identify things   Use dereferencable HTTP URIs in the Web of Data 15 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

RDF   A data model for representing metadata on the Web   Several statements (triples) form a graph 16 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

RDF   Links are an intrinsic RDF feature 17 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

RDF/XML, N3, Turtle, etc 18 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

RDFS   A language for describing vocabularies in a machine- understandable way 19 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

OWL   A more expressive language for expressing vocabularies and/or ontologies in a machine- understandable way 20 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

SKOS   A language for describing controlled vocabularies 21 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

SPARQL   A query language and protocol for accessing RDF data on the Web 22 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Linked Data Implementation Best Practices 23 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

How to publish vocabularies   Hash-based URIs   E.g., http://example.com/example1#ClassA   Suited to group the description of a moderate number of related terms into one document   Agent can retrieve terms with a single HTTP request   Slash-based URIs   E.g., http://example.com/example1/ClassB   Suited to split the descriptions of terms in large vocabularies into one document per term   No need for the agent to download a massive document to find the description of a term 24 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

How to publish vocabularies E.g.. extended configuration for hash namespace 25 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

How to publish vocabularies E.g.. extended configuration for hash namespace 26 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

How to publish Linked Data   Distinguish between   non-information resource   http://dbpedia.org/resource/The_Shining_%28film%29   Information resource   http://dbpedia.org/page/The_Shining_%28film%29 (HTML)   http://dbpedia.org/data/The_Shining_%28film%29 (RDF) 27 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

The Linking Open Data Project 28 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Some clarifications   Open Data: a philosophy, practice, or policy that data are freely available to everyone without restrictions from copyright, patents, a.s.o.   Linked Data: best practices for exposing, sharing, and connecting data using URIs and RDF   Linking Open Data: a W3C community project with the goal to extend the Web with a data commons by publishing various open data sets as RDF on the Web and by setting links between data items from different sources 29 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

As of October 2007 30 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Available Tools - Overview 33 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

RDF APIs   Jena Semantic Web Framework (Java)   http://jena.sourceforge.net/   Sesame   ARC (PhP)   http://arc.semsol.org/   Redland RDF – Ruby interface (Ruby)   http://librdf.org/docs/ruby.html   RDFlib (Python)   http://www.rdflib.net/ 34 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Triple Stores   Jena Semantic Web Framework (Java)   http://jena.sourceforge.net   Sesame (Java)   http://www.openrdf.org/   OpenLink Virtuoso   http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/   ARC (PhP)   http://arc.semsol.org/   … 35 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

References   RDF Primer: http://www.w3.org/TR/rdf-primer/   OWL 2 Overview: http://www.w3.org/TR/2009/REC-owl2- primer-20091027/   Best Practice Recipes for Publishing RDF Vocabularies: http://www.w3.org/TR/swbp-vocab-pub/   How to Publish Linked Data on the Web: http://www4.wiwiss.fu-berlin.de/bizer/pub/ LinkedDataTutorial/   Pedantic Web Group: http://pedantic-web.org/ 36 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

References   Linking Open Data Project   http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/ LinkingOpenData 37 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Agenda   Introduction   Multimedia Interlinking   Producing Linked Data   Multimedia Annotations   Existing Data Sets   Enriching Personal Media Collections   Linking Data   Consuming Linked Data 38 38 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Linked Data Publishing Steps The basic tenets of Linked Data are to:   use the RDF data model to publish structured data on the Web   use RDF links to interlink data from different data sources RDF data can be contained in   a single file (RDF/XML) or   embedded in an existing file with RDFa 39 39 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Principles   Resources all items of interest are called resources   Resource Identifiers Uniform Resource Identifiers (URIs) are used, use of HTTP URIs is strongly suggested   Representation of an information resource is a stream of bytes (HTML, JPG, RDF, …)   Dereferencing HTTP URIs 40 40 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Content Negotiation Example:   http://dbpedia.org/resource/Graz (URI identifying the non-information resource Graz)   http://dbpedia.org/data/Graz (information resource with an RDF/ XML representation describing Graz)   http://dbpedia.org/page/Graz (information resource with an HTML representation describing Graz) 41 41 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Content Negotiation with RDFa   When RDF is embedded in another representation (e.g. via RDFa) no content negotiation is needed   One representation is used for both humans and machines (X)HTML RDF XHTML+RDFa representation 42 42 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

RDFa example Plain (X)HTML: ... All content on this site is licensed under   <a href="http://creativecommons.org/licenses/by/3.0/">   a Creative Commons License </a>. (X)HTML with RDF embedded: ... All content on this site is licensed under   <a rel="license“ href="http://creativecommons.org/licenses/by/ 3.0/">   a Creative Commons License </a>. More information on RDFa: http://www.w3.org/TR/xhtml-rdfa-primer/ 43 43 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Choosing URIs   Resources are named with URI references   Choose „good“ URIs for your resources   Cool URIs for the Semantic Web http://www.w3.org/TR/cooluris/ 44 44 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Choosing URIs   Use HTTP URIs for everything   Define your URIs in an HTTP namespace under your control   Keep implementation details out of your URIs. Short, mnemonic names are better   http://dbpedia.org/resource/Graz VS   http://www.confuseme.com:2020/demos/xyz/cgi-bin/ resources.php?id=Graz   Try to keep your URIs stable and persistent Cool URIs don’t change!   Use some kind of primary key inside your URIs (e.g. when dealing with books use the ISBN, etc.) 45 45 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Which vocabularies to use?   Reuse terms from well-known vocabularies wherever possible   Only define new terms yourself if you can’t find required terms in existing vocabularies   List of well-known vocabularies: http://esw.w3.org/topic/TaskForces/Community Projects/LinkingOpenData/CommonVocabularies 46 46 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Some well-known vocabularies   Friend-of-a-Friend (FOAF), vocabulary for describing people.   Dublin Core (DC) defines general metadata attributes.   Semantically-Interlinked Online Communities (SIOC), vocabulary for representing online communities.   Description of a Project (DOAP), vocabulary for describing projects.   Simple Knowledge Organization System (SKOS), vocabulary for representing taxonomies and loosely structured knowledge.   Music Ontology provides terms for describing artists, albums and tracks.   Review Vocabulary, vocabulary for representing reviews.   Creative Commons (CC), vocabulary for describing license terms. 47 47 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

More best practices   You can mix terms from different vocabularies, e.g. rdfs:label and foaf:depiction   Use URI references from well-established data sources, e.g.:   Geonames   DBpedia   MusicBrainz   RDF Book Mashup 48 48 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Defining your own terms If you need to define own terms use RDFS or OWL. 1. Do not define new vocabularies from scratch 2. Provide for both humans and machines 3. Make term URIs dereferenceable 4. Make use of other people's terms 5. State all important information explicitly 6. Do not create over-constrained, brittle models; leave some flexibility for growth 49 49 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

What should the RDF contain? What triples should go into the RDF representation that is returned (after a 303 redirect) in response to dereferencing a URI identifying a non-information resource?   Description   Backlinks   (Related descriptions)   Metadata   Syntax: RDF/XML (+ maybe other serializations) 50 50 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Serving linked data   Things must be identified with dereferenceable HTTP URIs   When MIME-type application/rdf+xml is requested, a data source must return an RDF/XML description of the identified resource   Provide RDF links to other resources so that clients can navigate the Web of Data by following RDF links 51 51 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Serving static RDF files   RDF files generated manually or   generated by some software   Configure server for correct MIME types   When using Apache and server is not yet configured to return the correct MIME type add to httpd.conf or .htaccess: AddType application/rdf+xml .rdf   File size (should be < 1 MB) 52 52 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Serving relational databases   Several tools exist to generate RDF from relational databases 53 53 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Linked Data Publishing Steps For more information:   Tutorial „How to Publish Linked Data on the Web”   By Chris Bizer, Richard Cyganiak, Tom Heath   http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/ 54 54 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

RDB2RDF   W3C Incubator Group in 2008 & early 2009 to examine existing approaches for generating RDF from relational databases http://www.w3.org/2005/Incubator/rdb2rdf/   Survey of Current Approaches for Mapping of Relational Databases to RDF http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf   Incubator Group Report http://www.w3.org/2005/Incubator/rdb2rdf/XGR-rdb2rdf/ 55 55 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

RDB2RDF Working Group   W3C Working Group started in 2009 to standardize a language for mapping relational data and relational database schemas into RDF and OWL, tentatively called the RDB2RDF Mapping Language, R2RML http://www.w3.org/2001/sw/rdb2rdf/   First public results to be expected in early 2010   Participants from industry and academia 56 56 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Tools for Publishing Linked Data 57 57 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Pubby Linked Data Frontend   Provides Linked Data from SPARQL endpoint   data must be available in RDF already   if not: use a wrapper   Originally developed for DBpedia   Richard Cyganiak, Chris Bizer - FU Berlin   Provides dereferenceable HTTP-URIs   Simple HTML interface for browsing   Handles 303 redirects correctly   Content Negotiation (HTML, RDF/XML, N3)   Java Web application 58 58 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Pubby - Architecture Text Text   SPARQL endpoint must support DESCRIBE queries   supports multiple datasets (SPARQL endpoints) 59 59 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Pubby Setup How-To   Download and extract from: http://www4.wiwiss.fu-berlin.de/pubby/download   Setup a Servlet Container (e.g. Tomcat, Jetty...)   Use ant to build WAR or copy /webapp folder   Configure   config file in WEB-INF/config.n3   file location can be set by context param. “config-file” in web.xml   N3 syntax   General Server section (instance of conf:Configuration)   conf:webBase - root of URL of web application, e.g. http://localhost/   sub-section for each dataset   conf:sparqlEndpoint - SPARQL endpoint URI   conf:datasetBase - common URI prefix of resources in the dataset 60 60 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Wrapping Relational Databases   D2RQ-Map and D2R-Server (FU Berlin)   http://sites.wiwiss.fu-berlin.de/suhl/bizer/d2r-server/index.html)   Triplify (Uni Leipzig)   http://triplify.org)   OpenLink Virtuoso RDF Views   http://virtuoso.openlinksw.com/wiki/main/Main/ 61 61 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

D2RQ-Map and D2R-Server   Java   wraps any ODBC database to RDF   2 Components   D2RQ-Map (wrapping component): dumps + virtual   D2R-Server (adds SPARQL endpoint)   can be used in Jena applications (Assembler)   Automatic generation of mapping file (simple)   shell script: “generate-mapping” 62 62 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

D2RQ-Map and D2R-Server 63 63 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

D2R-Server How-To   Download/Extract   Generate mapping file automatically first   generate-mapping -o mapping.n3 -d driver.class.name! -u db-user -p db-password jdbc:url:..."   Inspect the generated mapping   Model your desired target graph   you should always know what you want...   also study your source database model   Adjust the mapping 64 64 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Mapping language   d2rq:Database   d2rq:ClassMap   d2rq:PropertyBridge   Rather expressive   Joins   Conditions   Value-translations 65 65 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Example Mapping 66 66 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Wrapping Spreadsheets   Excel2RDF, RDF123, TopBraid Composer   XLWrap (A. Langegger)   http://xlwrap.sourceforge.net/   supports cross tables, repetitive patterns in spreadsheets   arbitrary target graphs   powerful expressions (extensible, user-defined functions) 67 67 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

XLWrap Example 68 68 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Example Template Graph §  [ xl:uri "'http://example.org/revenue_' &! §  URLENCODE(SHEETNAME(A1) & '_' & B2 & '_' &! §  A4)"^^xl:Expr ] a ex:Revenue ;! §  ex:country "DBP_LOCALITY(SHEETNAME(A1))"^^xl:Expr ;! §  ex:year "DBP_YEAR(B2)"^^xl:Expr ;! §  ex:product "A4"^^xl:Expr ;! §  ex:itemsSold "B4"^^xl:Expr ;! Text §  ex:revenue "C4"^^xl:Expr .! 69 69 SAMT 2009 ––Tutorial Web of Data in the Context of Multimedia (WoDMM) SAMT 2009 Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 2 Dec 2009 Graz, Austria - Dec 2009

Agenda   Introduction   Multimedia Interlinking   Producing Linked Data   Multimedia Annotations   Existing Data Sets   Enriching Personal Media Collections   Linking Data   Consuming Linked Data 70 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Existing Relevant Linked Data Sets What is out there? 71 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

The Linked Data Cloud (a success story, 2007-2009) 72 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

74 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) 10/2007 Graz, Austria - 2 Dec 2009

75 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) 03/2008 Graz, Austria - 2 Dec 2009

Some numbers Data Set # of RDF Triples ACM RKB > 12,000,000 AudioScrobbler > 600,000,000 BBC Music + Programmes > 20,000,000 Bio2RDF > 2,000,000,000 data.gov > 5,000,000,000 DBpedia > 470,000,000 Freebase > 100,000,000 Geonames > 90,000,000 Linked Geo Data > 3,000,000,000 MusicBrainz > 60,000,000 RDF Book Mashup > 100,000,000 US Census Data > 1,000,000,000 Source: http://esw.w3.org/topic/TaskForces/CommunityProjects/LinkingOpenData/DataSets/Statistics 79 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

DBpedia: the Linked Data Hub   DBpedia [Auer07] is a Linked Data representation of Wikipedia content.   (Semi-)structured data are extracted (mostly from infoboxes) and are published as RDF.   DBpedia 3.4 (Nov. 2009) describes 2.9 million things, including persons, places, organizations, ...   Each thing has an URI; most of them have a label and an abstract, in up to 91 languages.   DBpedia provides > 8 millions links to other data sets (web pages and RDF), and 75,000 YAGO categories. 80 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

DBpedia Vocabularies   DBpedia uses its own set of terms, which are derived from the naming in Wikipedia Infoboxes.   Additionally used: RDF standard terms, FOAF.   The importance of DBpedia lies not primarily in the data it provides, but in the names (i.e., HTTP URIs) it provides. 81 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

BBC Linked Data   BBC is continually increasing their Linked Data services.   BBC Programmes publishes all broadcast programmes and provides URIs for them.   BBC Music provides data about music artists and links to DBpedia and MusicBrainz.   BBC uses Linked Data technology to link their internal, heterogeneous data sets [Kobi09].   Used vocabularies: RDF(S), FOAF, DC, Music Ontology, ... 84 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

DBtune   DBtune [Rai08] is a collection of music-related Linked Data sets, amongst others:   Jamendo (creative commons music site)   MusicBrainz (community music metadata)   AudioScrobbler (last.fm playcounts)   MySpace   URIs for entities can be retrieved by lookup services or through links to DBpedia and other data sets.   Used vocabularies: RDF(S), FOAF, DC, Music Ontology, ... 87 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Linked Movie Data Base   LMDB [Hass09] is an RDF representation of parts of the data from the Internet Movie Database (IMDb).   Data about ~40,000 films, ~30,000 actors, ~8,000 directors, etc.   Links to   DBpedia   YAGO   flickr   RDF book mashup   MusicBrainz   Geonames   Vocabularies: RDF(S), FOAF, Movie Ontology, SKOS, DC 90 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

There is more ...   flickr wrapper: generates links to flickr pictures on demand, represents them as RDF   Geonames: information about places (cities, countries)   Linked Geo Data: RDF representation of OpenStreetMap (geo data)   revyu.com: provides reviews for any kind of entities (including movies and music)   New York Times: >5.000 concepts from their archive   and many more ...   Data is out there ... use it! 93 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

References & Credits   The Linked Data Cloud is maintained by Richard Cyganiak and Anja Jentzsch.   [Auer07] S. Auer et al., DBpedia: A Nucleus for a Web of Open Data, Proc. ISWC 2007   [Kobi09] G. Kobilarov et al., Media Meets Semantic Web – How the BBC Uses DBpedia and Linked Data to Make Connections, Proc. ESWC 2009   [Rai08] Y. Raimond et al., A Web of Musical Information, Proc. ISMIR 2008   [Hass09] O. Hassanzadeh et al., Linked Movie Data Base, Proc. LDOW 2009 94 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data in the Context of Multimedia Part 1: Linked Open Data: Vision, Concepts and Technologies Linking Data Bernhard Haslhofer, Bernhard Schandl, Andreas Langegger, Wolfgang Halb, Tobias Bürger 95 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Linking Data   RDF links enable Linked Data browsers and crawlers to navigate between data sources and to discover additional data.   Properties used to link data depend on the application domain, e.g. :person1 foaf:knows :person2   Use owl:sameAs for URI aliases when two URIs refer to the same thing 96 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Linking Data Example: Equivalent URIs for http://data.linkedmdb.org/resource/film/2014 owl:sameAs 1.http://dbpedia.org/resource/The_Shining_(film) 2.http://data.linkedmdb.org/resource/film/2014 3. http://rdf.freebase.com/ns/guid. 9202a8c04000641f800000000046c3da   Linking can be de done   manually   automatically 97 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Setting RDF links manually   Usually only done in very small datasets like personal FOAF profiles (e.g. stating who you know by setting foaf:knows links)   Look up URI for the resource that you want to link to   uriqr.com   sindice.com   (SPARQL) queries to existing datasets   Use the URI identifying the resource,   http://dbpedia.org/resource/The_Shining_(film) not the URI for the document about it   http://dbpedia.org/page/The_Shining_(film) 98 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Auto-generating RDF links   Manual approach not feasible for larger datasets   Record linkage well-known problem in the DB world   Specialised pattern-based algorithms for individual problems   Use of unique identifiers (e.g. ISBN for books, ISIN for financial securites, ISO-3166 country codes, etc.)   Example:   http://dbpedia.org/resource/Harry_Potter_and_the_Half-Blood_Prince has a property dbpprop:isbn 747581088   owl:sameAs link can be easily generated to http://www4.wiwiss.fu-berlin.de/bookmashup/books/0747581088 99 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Tools for data interlinking   Input: 2 (or more) datasets + linkage specification   Output: links between the datasets Domain-independent tools:   SILK   ODD-Linker   RDF-AI   Knofuss Domain-specific tools:   LD-Mapper (Music Ontology)   RKB co-reference resolution system (publications) 100 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Overview RKB CRS LD-Mapper ODD RDF-AI Silk Knofuss Ontologies multi multi single single single multi Automation semi automatic semi semi semi semi dataset structure links spec. alignment alignment merged User input ad-hoc program none link spec. query method method ontology Silk-LSL Input format Java Prolog LinQL XML (XML) OWL Matching string, similarity string, adaptive techniques string propagation string, Wordnet string string learning Onto. alignment no no no no no yes, as input alignment alignment owl:sameAs format, merged format, merged Output owl:sameAs linkset linkset dataset linkset dataset Data access API local copy ODBC local copy SPARQL local copy Domain publications Music Ontology independent independent independent independent Overview generated by François Scharffe and Jérôme Euzenat http://melinda.inrialpes.fr 101 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Specification formats datasets resources links matching SPARQL endpoint, resources to interlink, link condition (for string matching, Silk-LSL graphs name resources type each resource) matchers combination string matching (for Knowfuss local copy (SPARQL query) fusion method each resource) RDF-AI local copy resource descriptions link description fuzzy string, wordnet LD-Mapper local copy resource query link description string matching synonym, hyponym, resource description weightedJaccard, ODD-linker local copy (table.column) link description, token intersect Overview generated by François Scharffe and Jérôme Euzenat http://melinda.inrialpes.fr 102 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

SILK   Silk - A Linking Framework for the Web of Data   http://www4.wiwiss.fu-berlin.de/bizer/silk/   Silk Link Specification Language   User specifies the type of resources to be linked and the comparison technique to be used   Silk uses many string comparison techniques, numerical and date similarity measures, concept distances in a taxonomy 103 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

SILK   Input: 2 datasets behind SPARQL endpoint + LSL specification   Output: linkset with owl:sameAs (or other user specified property) links between resources   Silk LSL example on next slide 104 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

<Interlink id="cities"> <LinkType>owl:sameAs</LinkType> <SourceDataset dataSource="dbpedia" var="a"> <RestrictTo> ?a rdf:type dbpedia:City </RestrictTo> </SourceDataset> <TargetDataset dataSource="geonames" var="b"> <RestrictTo> ?b rdf:type gn:P </RestrictTo> </TargetDataset> <LinkCondition> <AVG> <Compare metric="jaroSimilarity"> <Param name="str1" path="?a/rdfs:label" /> <Param name="str2" path="?b/gn:name" /> </Compare> <Compare metric="numSimilarity"> <Param name="num1" path="?city1/dbpedia:populationTotal" /> <Param name="num2" path="?city2/gn:population" /> <Compare> </AVG> </LinkCondition> <Thresholds accept="0.9" verify="0.7" /> <Output acceptedLinks="accepted_links.n3" verifyLinks="verify_links.n3" mode="truncate" /> </Interlink> 105 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Web of Data in the Context of Multimedia Part 1: Linked Open Data: Vision, Concepts, and Technologies: Consuming Linked Data Bernhard Haslhofer, Bernhard Schandl, Andreas Langegger, Wolfgang Halb, Tobias Bürger 106 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Agenda   URI Discovery   Data Discovery   Data Set Discovery   Tools and Libraries to Access and Consume Linked Data   Mashups and Browsers   Programmatic Access to Linked Data 107 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

URI Discovery 1.  Querying specific data sources, e.g., http://lookup.dbpedia.org 2.  Using dedicated search engines, e.g.,   Falcons http://iws.seu.edu.cn/services/falcons/   Sindice http://sindice.com   SWSE http://www.swse.org   Watson http://watson.kmi.open.ac.uk 108 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Search Engine: Falcons (1) Entry of keywords (2) Results of objects (3) Class hierarchy to refine search Try yourself: http://iws.seu.edu.cn/services/falcons/ 109 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Data Discovery 1.  Manual link traveral (i.e. follow rdfs:seeAlso or owl:sameAs links) 2.  Use of co-reference services, e.g. http://sameas.org 3.  Use of Uri-based query engines, e.g. http://sindice.org 110 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Sameas.org 111 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Sindice.org 112 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Data Set Discovery 1.  Manually, i.e., by browsing and selecting a data set from http://esw.w3.org/topic/SparqlEndpoints 2.  (Semi-) automatically, i.e., by exploiting VoiD, the Vocabulary of interlinked Datasets 113 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Describing Datasets   The problem:   Only human comprehensible descriptions of datasets available   Automation of tasks impossible such as   Efficient & effective search   Selection of datasets (for apps, interlinking targets)   Generation of maps, etc.   Solution: voiD, the “Vocabulary of Interlinked Datasets” provides a formal description of   What a dataset is about (topic, technical details).   How and under which conditions to access it.   How the dataset is interlinked with other datasets.   Qualitative level: type of interlinking.   Quantitative level: number of links, resources, etc.   How to discover the metadata. cf. K. Alexander, R. Cyganiak, M. Hausenblas, and J. Zhao "Describing Linked Datasets" Proceedings of LDOW 2009, 2009. 114 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

VoiD – Core concepts   A dataset is a set of RDF triples that are published, maintained or aggregated by a single provider.   A dataset is authoritative with respect to a certain URI namespace if it contains information about resources named by URIs in this namespace, and is published by the URI owner.   A linkset LS is a set of RDF triples where for all triples ti= ⟨si,pi,oi⟩ ∈ LS, the subject is in one dataset, i.e. all si are described in DS1 , and the object is in another dataset, i.e. all oi are described in DS2 . cf. K. Alexander, R. Cyganiak, M. Hausenblas, and J. Zhao "Describing Linked Datasets" Proceedings of LDOW 2009, 2009. 115 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

voiD Vocabulary cf. K. Alexander, R. Cyganiak, M. Hausenblas, and J. Zhao "Describing Linked Datasets" Proceedings of LDOW 2009, 2009. 116 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

voiD Usage Example cf. K. Alexander, R. Cyganiak, M. Hausenblas, and J. Zhao "Describing Linked Datasets" Proceedings of LDOW 2009, 2009. 117 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Tools and Applications to Consume Linked Data   Linked Data browsers   To explore things and datasets and to navigate between them.   Tabulator Browser (MIT, USA), Marbles (FU Berlin, DE), OpenLink RDF Browser (OpenLink, UK), Zitgist Dataviewr (Zitgist, USA), Disco Hyperdata Browser (FU Berlin, DE), Fenfire (DERI, Ireland)   Linked Data mashups   Sites that mash up (thus combine Linked data)   Revyu.com (KMI, UK), DBtune Slashfacet (Queen Mary, UK), DBPedia Mobile (FU Berlin, DE), Semantic Web Pipes (DERI, Ireland)   Search engines   To search for Linked Data.   Falcons (IWS, China), Sindice (DERI, Ireland), MicroSearch (Yahoo, Spain), Watson (Open University, UK), SWSE (DERI, Ireland), Swoogle (UMBC, USA) Listing on this slide by T. Heath, M. Hausenblas, C. Bizer, R. Cyganiak, O. Hartig 118 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Linked Data Browser: Marbles   Server-based Linked Data browser.   Formats RDF for XHTML using Fresnel.   Unique feature: Indicates the origin of displayed data using colored dots.   Support for different views:   Full view: all available data is displayed.   Summary view: returns a short textual summary about a resource.   Photo view: provides a photo for a given resource.   Retrieves data from multiple sources by (a) issuing parallel queries to multiple Linked Data search engines and (b) by following owl:sameAs and rdfs:seeAlso links. 119 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Linked Data Browser: Marbles (2) (1) Entry of query URL (2) Data display Try yourself: http:// marbles.sourceforge.net/ (3) Sources 120 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Linked Data Browser: gFacet cf. Heim, P., Ziegler, J., and Lohmann, S. "gFacet: A Browser for the Web of Data" In Proceedings of IMC-SSW 2008, 2008. Try yourself: http://gFacet.org 121 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Mashup: Revyu.com Picture from revyu.com Try yourself: http://revyu.com 122 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Example Mashup: DBPedia Mobile Pictures from DBPedia Mobile Try yourself: http://wiki.dbpedia.org/DBpediaMobile 123 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

Libraries to Programmatically Access the Web of Data   SPARQL JavaScript Library, http://www.thefigtrees.net/lee/blog/2006/04/ sparql_calendar_demo_a_sparql.html   ARC for PHP, http://arc.semsol.org/   RAP – RDF API for PHP http://www4.wiwiss.fu-berlin.de/bizer/rdfapi/index.html   SPARQL Wrapper (Python), http://sparql-wrapper.sourceforge.net/   PySPARQL (Python), http://code.google.com/p/pysparql/   DARQ (Distributed ARQ), http://darq.sourceforge.net/   Semantic Web Client library (SWClLib) for Java, http://www4.wiwiss.fu-berlin.de/bizer/ng4j/semwebclient/ Listing on this slide by O. Hartig, J. Sequeda 124 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

What’ll come next   Part 2: Linked Multimedia 125 SAMT 2009 – Tutorial Web of Data in the Context of Multimedia (WoDMM) Graz, Austria - 2 Dec 2009

SAMT09 - Web of Data Tutorial - Part 1

by Bernhard Haslhofer

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SAMT09 - Web of Data Tutorial - Part 1 Presentation Transcript