Semantic Web Applications Wiltrud Kessler Institut f¨urMaschinelle Sprachverarbeitung Universit¨atStuttgart Semantic Web Winter 2015/16 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. http://creativecommons.org/licenses/by-nc-sa/3.0/ SW Applications Metadata Integrate Create Find Suggested Reading The Semantic Web Stack [W3C, Tim Berners-Lee] User Interface, Software Agents Trust Proof Logic, Rules Ontology, OWL SPARQL RDFS RDF Encryption XML, XMLSchema, Namespaces Digital Signatures URI Unicode, UTF-8 Wiltrud Kessler Semantic Web Applications 2 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Outline Semantic Web Applications Add Metadata Data Integration Create Semantic Data Finding Semantic Information Suggested Reading Wiltrud Kessler Semantic Web Applications 3 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Outline Semantic Web Applications Add Metadata Data Integration Create Semantic Data Finding Semantic Information Suggested Reading Wiltrud Kessler Semantic Web Applications 4 / 44 SW Applications Metadata Integrate Create Find Suggested Reading What are Semantic Web Applications? Some propositions for a definition: I SW applications use standardized SW languages, e.g., RDF, OWL, SPARQL. I SW applications have something to do with metadata, data exchange and integration. I SW applications follow the vision of having humans and machines interact in a web of knowledge. I ... ? Wiltrud Kessler Semantic Web Applications 5 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Outline Semantic Web Applications Add Metadata Data Integration Create Semantic Data Finding Semantic Information Suggested Reading Wiltrud Kessler Semantic Web Applications 6 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Add Metadata I Metadata is \data about data": I author, contact, source, . I creation date, location, . I format, type of data, language, . I legal information, . I description of content, keywords, . I Metadata is only useful when it comes with semantics, i.e., is standardized across sources. Wiltrud Kessler Semantic Web Applications 7 / 44 SW Applications Metadata Integrate Create Find Suggested Reading RSS { Markup for Blogs I RSS originally stood for RDF Site Summary in RSS 0.9. I RSS 0.91 was renamed to stand for Rich Site Summary and RDF elements were removed, this developed into XML-only RSS 2.0 (Really Simple Syndication 2.0) I In 2003 an alternative format, Atom, was created. I Used by many blogging services, e.g., WordPress, Blogger, . I RDF File (RSS 1.0): http://web.resource.org/rss/1.0/schema.rdf I RSS 2.0: http://www.rssboard.org/rss-specification I Atom: http://tools.ietf.org/html/rfc4287 Wiltrud Kessler Semantic Web Applications 8 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Microformats { Low-level semantic markup I Use attribute class to add semantic markup from a defined vocabulary to HTML/XHTML tags. I Community-effort, no standardization gremium. I Well-known microformats: geo (geographical coordinates), hCard (contact information), hCalendar (events) I Web page: http://microformats.org/ I hCard creator: http://microformats.org/code/hcard/creator.html I hCalendar creator: http: //microformats.org/code/hcalendar/creator.html Wiltrud Kessler Semantic Web Applications 9 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Microformats { Example hCard <link rel="profile" href="http://microformats.org/profile/hcard"> ... </head> ... <ul class="vcard"> <li class="fn">Joe Doe</li> <li class="org">The Example Company</li> <li class="tel">604-555-1234</li> <li><a class="url" href="http://example.com/"> http://example.com/</a></li> </ul> Wiltrud Kessler Semantic Web Applications 10 / 44 SW Applications Metadata Integrate Create Find Suggested Reading RDFa { RDF in HTML I Add attributes to HTML to embed RDF statements. I Can embed arbitrary RDF, not limited to a vocabulary (like with microformats). I W3C recommendation since 2008. I RDFa Core recommendation: http://www.w3.org/TR/rdfa-core/ I RDFa Primer: http://www.w3.org/TR/xhtml-rdfa-primer/ Wiltrud Kessler Semantic Web Applications 11 / 44 SW Applications Metadata Integrate Create Find Suggested Reading RDFa { Example <p xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> In his latest book <cite property="dc:title">Wikinomics</cite>, <span property="dc:creator">Don Tapscott</span> explains deep changes in technology, demographics and business. The book is due to be published in <span property="dc:date" content="2006-10-01"> October 2006</span>. </p> Wiltrud Kessler Semantic Web Applications 12 / 44 SW Applications Metadata Integrate Create Find Suggested Reading CC REL { Copyright Information I Creative Commons offers free, easy-to-undestand licenses. I Offer an RDF vocabulary to describe licenses { makes copyright information machine-readable. I Useful for: publishers, image search, display in browser, . I Web page: http://creativecommons.org/ns I RDF File: http://creativecommons.org/schema.rdf Wiltrud Kessler Semantic Web Applications 13 / 44 SW Applications Metadata Integrate Create Find Suggested Reading CC REL { Example @prefix cc: <http://creativecommons.org/ns#> . <http://lessig.org/blog/> xhtml:license <http://creativecommons.org/licenses/by-sa/3.0/> ; dc:title "The Lessig Blog" ; cc:attributionName "Larry Lessig" ; cc:attributionURL <http://lessig.org/> ; dc:type dcmitype:Text . <http://creativecommons.org/licenses/by-sa/3.0/> cc:permits cc:Reproduction ; cc:permits cc:Distribution . Wiltrud Kessler Semantic Web Applications 14 / 44 SW Applications Metadata Integrate Create Find Suggested Reading FOAF { Friend of a Friend I RDF/OWL vocabulary about persons and social networks. I Used by many blogging services: WordPress, TypePad, . I Used by Semantically-Interlinked Online Communities Project (SIOC) to interconnect blogs, forums and mailing lists. I Crucial part of WebID, a set of proposed standards for identification, and authentication on HTTP based networks. I Web page: http://www.foaf-project.org/ I Search FOAF: http://www.foaf-search.net/ I Create a FOAF profile: http://www.ldodds.com/foaf/foaf-a-matic.html Wiltrud Kessler Semantic Web Applications 15 / 44 SW Applications Metadata Integrate Create Find Suggested Reading FOAF { Example @PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> . <#JW> rdf:type foaf:Person ; foaf:name "Jimmy Wales" ; foaf:mbox <mailto:[email protected]> ; foaf:homepage <http://www.jimmywales.com/> ; foaf:nick "Jimbo" ; foaf:depiction <http://www.jimmywales.com/aus_img_small.jpg> ; foaf:interest <http://www.wikimedia.org> ; foaf:knows [ rdf:type foaf:Person ; foaf:name "Angela Beesley" ]. Wiltrud Kessler Semantic Web Applications 16 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Outline Semantic Web Applications Add Metadata Data Integration Create Semantic Data Finding Semantic Information Suggested Reading Wiltrud Kessler Semantic Web Applications 17 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Data Integration I Make sure we talk about the same thing by referencing formally specified, language independent knowledge. I \Knowledge" consists of two parts: I General world knowledge { upper ontologies. I Domain-specific knowledge { domain vocabulary / ontology. I Often a common vocabulary is sufficient (RDF), but sometimes more semantics is needed (RDFS/OWL). I Data integration is a major challenge and cost factor in today's data-driven world! Wiltrud Kessler Semantic Web Applications 18 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Upper Ontologies Definition [Wikipedia] An upper ontology is an ontology which describes very general concepts that are the same across all knowledge domains. I Goal: Support interoperability between specific ontologies { they all link back to an upper ontology. I Problem: Nobody agrees on one such ontology, there are many different upper ontologies. Wiltrud Kessler Semantic Web Applications 19 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Cyc and OpenCyc Cyc is an upper ontology, the project started in 1984. Parts of the project are released as OpenCyc under an open source licence, which contains 239,000 concepts and 2,093,000 facts and can be browsed on the OpenCyc website. I Project website: http://www.cyc.com I OpenCyc: http://www.cyc.com/platform/opencyc Wiltrud Kessler Semantic Web Applications 20 / 44 SW Applications Metadata Integrate Create Find Suggested Reading UMBEL { Upper Mapping and Binding Exchange Layer UMBEL is an upper ontology of about 28,000 reference concepts extracted from OpenCyc. UMBEL also is a vocabulary for aiding ontology mapping, including expressions of likelihood relationships distinct from exact identity or equivalence. UMBEL has about 48,000 formal mappings to DBpedia, PROTON, GeoNames, and schema.org, and provides linkages to more than 2 million Wikipedia pages (English version). I Project website: http://www.umbel.org Wiltrud Kessler Semantic Web Applications 21 / 44 SW Applications Metadata Integrate Create Find Suggested Reading Domain-specific Ontologies Definition [Wikipedia] A domain ontology (or domain-specific ontology) represents concepts which belong to part of the world. Particular meanings of terms applied to that domain are provided by domain ontology. I Goal: Model exactly what is needed in