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Digital Enterprise Research Institute                                                    www.deri.ie




                                                Hello Open Data World!
                                           The Web of Data for the Pragmatic Developer
                                            Alexandre Passant & Giovanni Tummarello
                                              SEMTECH, San Jose, California 2009




 Copyright 2008 Digital Enterprise Research Institute. All rights reserved.
Outline
Digital Enterprise Research Institute                                  www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




                         NB: Tutorial adapted from the WWW2009 “Hello Open
                         World” presentation by Alexandre Passant and Michael
                         Hausenblas

       2
Speakers introduction
Digital Enterprise Research Institute                      www.deri.ie




            Alexandre Passant
                   Postdoctoral researcher, DERI Galway
                   Social Software and Semantic Web
                   http://apassant.net


            Giovanni Tummarello
                   Research Fellow, DERI Galway
                   Web of Data Search and Mashups
                   http://g1o.net




       3
DERI Galway
Digital Enterprise Research Institute                    www.deri.ie




            Enabling Networked Knowledge
                   Social Semantic Information Spaces
                   Semantic Reality
            Approximately 130 people




       4
Companion website
Digital Enterprise Research Institute                       www.deri.ie




                                http://helloopenworld.net




       5
What is this tutorial about
Digital Enterprise Research Institute                                             www.deri.ie




            What you will learn
                   Web of Data principles
                   Architecture principles for applications on the Web of Data
                   Finding and creating structured data
                   Using vocabularies and lightweight inference
                   Querying Web data with SPARQL and with Sindice
                   User interfaces and mash-ups
            What you will not
                   Ontology mapping and alignment
                   Advanced rules languages
                   Complex SPARQL querying


       6
What you should be able to do after this
       tutorial
Digital Enterprise Research Institute                                                 www.deri.ie




            Explain the Web of Data to your CTO / Students /
             Advisor / Grandmother
                   Spread the values of the Web of Data
            Join the Web of Data
                   Effectively enriching your existing pages and applications with
                    annotations that will help your data to be found and integrated
            Leverage the Web of Data for your apps
                   Finding data “out there” and reusing it
                   Using open-source and xAMP technologies
                   Creating, consuming and mashing-up RDF data




       7
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       8
Motivation
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       Yahoo




    Google
    Rich
    Snippets


       9
Motivation
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            More and more data is available on the Web
                   Structured data, in RDF, microformats, etc.
                   Reusing Data is a value for your application !
            Up to now people would develop against proprietary
             APIs (such as from Flickr, Google, etc.)
                   Loss of time for developers
            The Web of Data …
                   Provides a uniform data model (RDF)
                   Provides a uniform API for accessing data (RDF/SPARQL)
                   Provide common semantics for this data (RDFS/OWL)
                   Enables serendipitous usage of data


       10
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       11
What is the Web of Data?
Digital Enterprise Research Institute                                       www.deri.ie




            Web of information structured via standards and made
             available on the Web
                   Microformats and GRDDL
                   RDF using various serializations: RDF/XML, RDFa, etc.




       12
RDF
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            RDF: Resource Description Framework
            As of RDF abstract syntax, a data model: a directed,
             labeled graph based on URIs
                   RDF is not XML !
                   RDF/XML is only one of the multiple way to serialize RDF data
                    (N3, RDFa …)
            Triple: (subject predicate object)
                   subject
                   predicate
                   object
               <http://sw-app.org/#i><http://xmlns.com/foaf/0.1/knows>
               <http://apassant.net/alex>.


       13
RDF
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       14
RDF
Digital Enterprise Research Institute                                         www.deri.ie




       @prefix dcterms: <http://purl.org/dc/terms/> .

       <http://deri.ie/teaching/tutorials/lod-intro>
       dcterms:title “Tutorial on Linked Data - A Practical Introduction” ;
       dcterms:author<http://sw-app.org/mic.xhtml#i> ;
       dcterms:subject <http://dbpedia.org/resource/Linked_Data> .




       15
“Semantic Data” on the Web
Digital Enterprise Research Institute                                        www.deri.ie




            Web of Data == the Semantic Web?
                   Not really, it’s the “Web” facing part of it
                   It’s part of it, a kind of subset
                   In contrast to the full-fledged Semantic Web vision, the Web
                    of Data more about raw data publishing in interoperable
                    format than about logic inference and reasoning on it




       16
What is the Web of Data?
Digital Enterprise Research Institute   www.deri.ie




       17
Web of data via “Linked Data”
Digital Enterprise Research Institute                                                     www.deri.ie




            Linked data principles, by Tim Berners-Lee, ca. 2006
                   Use URIs to identify things (anything, not just documents)
                       – “To benefit from and increase the value of the World Wide Web,
                         agents should provide URIs as identifiers for resources”
                       – http://www.w3.org/TR/webarch/
                   Use HTTP URIs – globally unique names, distributed ownership
                    – allows people to look up things
                   Provide useful information in RDF – when someone looks up a
                    URI
                   Include RDF links to other URIs– to enable discovery of related
                    information
                   Example http://dbpedia.org/resource/Dublin



       18
Linked data growth
Digital Enterprise Research Institute   www.deri.ie

              2007




                                        2008




       19
Linked data growth
Digital Enterprise Research Institute            www.deri.ie


                                        2008




                                               2009




       20
Needed: shared vocabularies (Ontologies)
Digital Enterprise Research Institute                                           www.deri.ie




            Ontologies provide common semantics for the Web of
             Data
                    “An ontology is a specification of a conceptualization.”
            Main languages are RDFS and OWL
                   This tutorial will mainly focus on RDFS
                   OWL allows advanced axioms (contraints, unions …)
            Classes and properties
                   :Person a rdfs:Class
                   :father a rdfs:Property
                   :father rdfs:domain :Person
                   :father rdfs:range :Person


       21
Ontologies
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            Hierarchies in ontologies
                   Are needed to define narrower / broader concepts
                   :LivingThing > :Person
            Can be applied to both classes and properties
                   :Person rdfs:subClassOf :LivingThing
                   :father rdfs:subPropertyOf :familyRelation
            Inference engines can take advantage of it to create new
             facts
                   Can be used when querying information
                   Retrieve all :LivingThing instances with a :familyRelation
                       – Will get :Person and :father !



       22
Notable ontologies
Digital Enterprise Research Institute                                    www.deri.ie




            Social networks and social data
                   FOAF – Friend Of A Friend
                   SIOC – Semantically-Interlinked Online Communities
            Software development
                   DOAP – Description Of A Project
                   BEATLE - Bug And Enhancement Tracking LanguagE
            Comprehensive / Top-level
                   Yago (From Wikipedia)
                   OpenCYC
            Taxonomies
                   SKOS – Simple Knowledge Organisation System


       23
Zooming in: FOAF Ontology
Digital Enterprise Research Institute                           www.deri.ie




            A model to describe people and social networks
                   http://foaf-project.org
            Concepts
                   Person, OnlineAccount, Document, etc.
            Properties
                   name, homepage, holdsAccount, knows, etc.




       24
FOAF in use
Digital Enterprise Research Institute                                                   www.deri.ie




            Google Social Graph API
                   http://code.google.com/intl/fr/apis/socialgraph/
            Uses FOAF information already there on the Web to find
             your contacts
                   http://socialgraph-
                    resources.googlecode.com/svn/trunk/samples/findcontacts.html
                   E.g.: http://apassant.net
                       – http://socialgraph-
                         resources.googlecode.com/svn/trunk/samples/findcontacts.html?q=
                         http%3A%2F%2Fapassant.net
                       – Contacts found in various FOAF files that link to myself and to my
                         profile




       25
Zooming in: SIOC Ontology
Digital Enterprise Research Institute                                         www.deri.ie




            Describe Web communities and their social interactions
                   Who’s writing what, who’s answering who, etc.
                   A simple model to ensure easy-integration into existing
                    applications
                   Lightweight: one core ontology, 4 modules
            Plug-ins /core-feature for several CMS
                   Drupal, Wordpress etc.
                   Enables interoperability between social applications
                   http://sioc-project.org




       26
The SIOC ontology
Digital Enterprise Research Institute               www.deri.ie




            The main classes and properties are:




       27
Combining FOAF + SIOC
Digital Enterprise Research Institute   www.deri.ie




       28
Adoption of SIOC
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       29
Which ontologies to use ?
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            SearchMonkey Vocabularies
                   http://developer.yahoo.com/searchmonkey/smguide/profile_voca
                    b.html




       30
Which ontologies to use ?
Digital Enterprise Research Institute                                               www.deri.ie




            How to Publish Linked Data on the Web
                   http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/




       31
Extending ontologies ?
Digital Enterprise Research Institute                                  www.deri.ie




            What if existing ontologies are not enough for your
             needs ?
                   Create a new one
                   … or extend existing ones !
            Ontologies can be extended in a decentralized way
                   E.g. you can create a subproperty of foaf:knows,
                    “attendedTutorialWith”, in your own ontology
                   Publish in on your own
                   Or use http://open.vocab.org




       32
Attention: Domain and range
Digital Enterprise Research Institute                                         www.deri.ie




            Domain and range of properties are descriptive, not
             prescriptive
                   Example if we say :father rdfs:domain :Person
                       – Not only pre-defined Persons can be fathers
                       – But every father is a Person !
                   Consequence 1: One triple is enough to describe several
                    informations
                   Consequence 2: DON’T use foaf:homepage for a shoe
            For details
                   Based on RDF semantics (Rule rdfs2)
                   http://www.w3.org/TR/rdf-mt/



       33
Linking Open Data Project
Digital Enterprise Research Institute                                                       www.deri.ie




            Community project with W3C support started in early
             2007 [LOD]: http://linkeddata.org
            Idea: take existing (open) data sets and make them
             available on the Web in RDF
            Interlink them with other data sets
                   Expand the network effect of Linked Data !
            Raw Data Now !
                   Tim Berners-Lee TED talk
                   http://www.ted.com/index.php/talks/tim_berners_lee_on_the_nex
                    t_web.html
                                        Kudos to Tom Heath and Richard Cyganiak; the material in
                                        this section is heavily based on their work.


       34
Linking Open Data Project
Digital Enterprise Research Institute      www.deri.ie



                                        May 2007




       35
Linking Open Data Project
Digital Enterprise Research Institute      www.deri.ie



                                        Feb 2009




       36
Notable datasets of the LOD cloud
Digital Enterprise Research Institute                                            www.deri.ie




            Linking Open Data
                   Community project started in 2007 - http://linkeddata.org
            Dbpedia – http://dbpedia.org
                   Wikipedia in RDF: “more than 2.6 million things, including at
                    least 213,000 persons, 328,000 places, 57,000 music albums,
                    36,000 films, 20,000 companies”
            Geonames – http://geonames.org
                   “over eight million geographical names”: coordinates, etc.
            Freebase - http://rdf.freebase.com/
                   “5203825 Topics 14110006 Named Entities”
                   E.g. http://rdf.freebase.com/rdf/en.blade_runner



       37
Linking Open Data Project
Digital Enterprise Research Institute      www.deri.ie



                                        DBpedia




       38
Linking Open Data Project
Digital Enterprise Research Institute     www.deri.ie



                                        Geonames




       39
Querying dbpedia
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            Programmatically (via SPARQL, see later)
            Via User Interface
                   http://wikipedia.aksw.org




       40
Tools and Applications
Digital Enterprise Research Institute                                           www.deri.ie




            Linking Open Data homepage [LOD] has
                   Browsing with Tabulator, VisiNav, Sig.ma, DBpedia Mobile,
                    iLOD, etc.
                   Searching with Sindice, SWSE, Falcons, etc.
                   Mashups, e.g. Revyu, BBC Music, DERI Pipes
            See further
             http://esw.w3.org/topic/SweoIG/TaskForces/Community
             Projects/LinkingOpenData/Applications




       41
Tools and Applications
Digital Enterprise Research Institute           www.deri.ie



                                        DBpedia Mobile




       42
Applications integration
Digital Enterprise Research Institute           www.deri.ie



                                        BBC music beta




       43
Typical architectures of applications
        for the Web of Data (1/2)
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from: Heitmann, B., et al., “Towards a reference architecture for Semantic Web
applications,” Proceedings of the 1st Int. Web Science Conference, 2009


       44
Typical architectures of applications
        for the Web of Data (2/2)
Digital Enterprise Research Institute                                www.deri.ie



       Data Interface: Abstraction layer regarding implementation,
        number and distribution of persistence layers.
       Persistence Layer: Persistent storage of data and run time state.
       User Interface: Human accessible interface for using application
        and viewing data. (“read-only”)
       Annotation User Interface: Edit, create, import or export data.
       Integration Service: Merge Structure, Syntax or Semantics of data
        from multiple heterogeneous sources.
       Search Engine: Search on content or semantic features.
       Crawler: Retrieval of remote data for integration service.




       45
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       46
Creating Structured Data
Digital Enterprise Research Institute                                              www.deri.ie




            Overview of different methods:
                   Create RDF/XML manually (using your favourite text-editor or
                    Web-based interfaces)
                   Create XHTML+RDFa documents and use GRDDL
                    transformation
                       – For both human and machines !
                   Use exporters / wrappers for existing service
                   Use applications that natively expose RDF data
                   Provide mappings from RDBMS to RDF data
            Hands-on !
                   We will go through several of them to create interlinked RDF
                    data from various sources of structured data


       47
Getting a FOAF profile
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            Or how to give yourself a URI
                   Be part of the Web of Data
            Create your FOAF file
                   http://www.ldodds.com/foaf/foaf-a-matic (requires hosting -
                    provided during the tutorial)
                   http://foafbuilder.qdos.com/builder/ (requires OpenID)
            I already have an homepage, what about duplication of
             information ?
                   Use RDFa to embed RDF annotations in yourhomepage !
                   More on thistopic in a few slides




       48
Extend your FOAF profile
Digital Enterprise Research Institute                                               www.deri.ie




            The foaf:knows property aims to represent social
             connections between people
                   :alex foaf:knows :michael
            Going further with the relationship vocabulary
                   http://vocab.org/relationship/: colleagueOf, hasMet …
            Add some people from the workshop, validate, and
             upload to the workshop repository
                   http://www.w3.org/RDF/Validator/
                   http://helloopenworld.net/semtech09/data
                   You finally got a URI !
                       – http://helloopenworld.net/semtech09/data/apassant.rdf#me



       49
Defining personal interests
Digital Enterprise Research Institute                                                   www.deri.ie




            Instead of modeling interests as plain-text strings, use
             URIs to describe them !
                   Allows interlinking of various resources for advanced query
                    purposes: “find all people that like movies directed by Tarantino”
            And link them to you using foaf:topic_interest
                   :me foaf:topic_interest :movie
            But … where to get these URIs ?
                   The Linking Open Data cloud !
                       – Provide URIs for million of concepts, esp. thanks to DBpedia
                   Sindice can be used to find URIs for a given concept
                       – http://sindice.com




       50
Defining personal interests
Digital Enterprise Research Institute   www.deri.ie




       51
Defining personal interests
Digital Enterprise Research Institute   www.deri.ie




       52
RDFa and GRDDL
Digital Enterprise Research Institute                                            www.deri.ie




            GRDDL is a mechanism to transform any kind of XML to
             RDF
            XHTML+RDFa is XML, hence GRDDL can extract it
                   Simply embeds RDFa annotations in your HTML code
                   Indexed by Yahoo! SearchMonkey and Google
                   Done via XSLT, available at http://www.w3.org/2008/07/rdfa-xslt




       53
RDFa and GRDDL
Digital Enterprise Research Institute                             www.deri.ie




            The GRDDL Primer athttp://www.w3.org/TR/grddl-
             primer/#scheduling shows the overall processing of
             XHTML+RDFa:




       54
RDFa and GRDDL
Digital Enterprise Research Institute          www.deri.ie




            http://sdow2009.semanticweb.org




       55
RDFa and GRDDL
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            http://sdow2009.semanticweb.org
                   Browse source to check RDFa annotations




       56
RDFa and GRDDL
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            http://sdow2009.semanticweb.org
                   Header contains prefixes and links to the GRDDL transformation




       57
RDFa and GRDDL
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            http://sdow2009.semanticweb.org
                   Webpage can be translated to native RDF/XML using an RDFa
                    distiller - http://www.w3.org/2007/08/pyRdfa/




       58
AddRDFa to yourhomepage
Digital Enterprise Research Institute                                          www.deri.ie




            Choose the right DTD
                   http://www.w3.org/TR/rdfa-syntax/DTD/xhtml-rdfa-1.dtd
            Addprefixesdefinition in the header
                   Depending on ontologies youwill use
            Addappropriate profile
                   E.g. http://ns.inria.fr/grddl/rdfa/
            Addaditionalmarkup
                   E.g. rel, about, typeof


            Example
                   http://helloopenworld.net/semtech2009/files/profile.html


       59
Wrappers for existing sources
Digital Enterprise Research Institute                                           www.deri.ie




            Creating and maintaining a FOAF file by hand can be a
             time-consuming task
                   How can we automatically get RDF data from existing sources ?
            What about Web 2.0 services in which we already give
             lots of personal information ?
                   Most of them provide APIs to get structured information (JSON,
                    XML …) about the user profiles, content, etc.
                   API to RDF wrappers can easily be implemented




       60
Wrappers for Web 2.0 services
Digital Enterprise Research Institute                                           www.deri.ie




            Facebook wrapper
                   Generates a FOAF file from your Facebook profile
                   http://www.dcs.shef.ac.uk/~mrowe/foafgenerator.html
            Flickr wrapper
                   Generates FOAF + SIOC + links to geographical information
                    (using geonames.org)
                   http://apassant.net/home/2007/12/flickrdf




       61
RDFification services
Digital Enterprise Research Institute                           www.deri.ie




            Translates many structured sources into RDF
                   URIBurner
                       – http://linkeddata.uriburner.com/
                       – Open Source, C++ , Based on Virtuoso
                   Any23
                       – Sindice sponsored
                       – Open Source, Java based
                   Swignition
                       – http://buzzword.org.uk/swignition/
                       – Perl based
                   Triplr
                       – Purelysyntactic, fast
                       – http://triplr.org


       62
Interlinking identities
Digital Enterprise Research Institute                                            www.deri.ie




            The previous exporters create different URIs
                   A need to unify your online identity on the Web of Data
            owl:sameAs
                   Used to state that two resources with different URIs are about
                    the same entitiy
                   http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/
            owl:InverseFunctionalProperty
                   foaf:mbox, foaf:openid, etc.
                   “Inverse Functional” properties can be used to identify
                    uniqueness for a foaf:Person




       63
Interlinking identities and networks
Digital Enterprise Research Institute         www.deri.ie




       64
Native export of RDF data
Digital Enterprise Research Institute                                                    www.deri.ie




            CMS can expose RDF data natively using dedicated
             plug-ins
                   SIOC Export for Drupal: http://drupal.org/project/SIOC
                   Provide RDF export of each blog post
                       – http://apassant.net/blog/2009/03/07/call-suggested-features-sparql-
                         working-group
                       – http://apassant.net/sioc/node/235
                   Using RDF autodiscovery feature in the HTML header
                       – So that RDF can be discovered when browsing HTML
                       – Semantic Radar: http://sioc-project.org/firefox
            RDFa to be included in Drupal7 core !
                       – http://groups.drupal.org/node/16597
                       – 100.000’s of RDFa-powered websites


       65
Overview: SIOC for vBulletin
Digital Enterprise Research Institute   www.deri.ie




       66
Relational to RDF Mapping
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            Relational data (RDB) is structured data and can be
             mapped to RDF straight-forward
            Main issues:
                   Closed-world vs. open-world modeling
                   Assigning URIs for entities (records)
                   Mapping language expressivity
            For a state-of-the-art see
             http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_Su
             rveyReport.pdf




       67
Relational to RDF Mapping
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            Standardization
                   W3C RDB2RDF Incubator Group 2008/2009
                   Upcoming W3C RDB2RDF Working Group
            Current solutions (see state-of-the-art)
                   D2RQ
                       – http://www4.wiwiss.fu-berlin.de/bizer/d2rq/
                       – DBLP in RDF: http://dblp.l3s.de/d2r/
                   OpenLink’s Virtuoso
                       – http://www.openlinksw.com/virtuoso/
                   Triplify
                       – http://triplify.org




       68
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       69
Discovery of RDF data
Digital Enterprise Research Institute                               www.deri.ie




            Discovery is the process of starting with a URI and learn
             more about the resources that can be accessed or
             described through it
            .. Without using a search engine




       70
Discovering RDF data
Digital Enterprise Research Institute                                                        www.deri.ie




            Simple case: Dereference
                   “Follow-Your-Nose” approach
            Semantic Sitemaps
                   to find SPARQL endpoints or data dumps
                    http://sw.deri.org/2007/07/sitemapextension/
            Links from within the RDF
                   voiD, vocabulary of interlinked datasets
                       –   Allows to learn what a dataset is about
                       –   Provides quantitative data on interlinking (statistics)
                       –   Enables to deliver licensing, provenance and access information
                       –   http://semanticweb.org/wiki/VoiD
                   SeeAlso, owl:import or simply dereference other URIs


       71
Semantic Web Sitemaps
Digital Enterprise Research Institute                                          www.deri.ie




            Easy to create metadata from your existing database
             (D2RQ, microformats etc)
            But you need to tell the world about it!
                   More is needed to make your data useful (e.g. linking to OTHER
                    URIs if your entities are not something completely “yours”)
                   Need to make the world know your data is there.
            Semantic Web Sitemaps can help




       72
Large quantities of linked data: how to
       expose?
Digital Enterprise Research Institute                                             www.deri.ie




            The fact that the data is HTTP retrievable in small bits
             makes it crawlable.
            But data producers are very scared of this:
                   Million of hits for each refresh
            And clearly something better must be possible
                   Most data producers do in fact already provide full dumps of the
                    base data
                   Or SPARQL endpoints




       73
Extending Sitemaps to expose data
Digital Enterprise Research Institute                                            www.deri.ie




            Sitemaps:
                   Originally by Google, immediately adopted by all (Yahoo, MSN)
                    etc
                   Expose the “deep web”, by providing a list of pages “to be
                    crawled”
                   Written in XML, Linked directly in the robot.txt
       Example:
            <?xml version="1.0" encoding="UTF-8"?>
            < urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
             < url>
            < loc>http://www.example.com/</loc>
                < lastmod>2005-01-01</lastmod>
                 < changefreq>monthly</changefreq>
                 < priority>0.8</priority>
            </url>
            </urlset>



       74
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       75
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       76
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       77
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       78
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       79
The Semantic Sitemap Extention
Digital Enterprise Research Institute                                         www.deri.ie



      Example first:


      <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
                  http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
                  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
         xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd">


      <sc:dataset>
      <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel>
      <sc:dataDumpLocation>http://example.org/cataloguedump.rdf
      </sc:dataDumpLocation>
         <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix>
         <changefreq>monthly</changefreq>
      </sc:dataset>

      </urlset>




       80
How it is meant to be used
Digital Enterprise Research Institute                                                 www.deri.ie




            As a crawler
                   If you are given a URL for an RDF site check for the sitemap
                   If a dump is available, download that instead


            As a client
                   If you have a dump, and want an update
                   Check the sitemap, to locate it in case it has changed position
                   Or to locate a SPARQL endpoint




       81
Or Search!
Digital Enterprise Research Institute                                              www.deri.ie




            Sindice Search Engine
                   http://sindice.com
            Look up by RDF by keywords and on property/value
             descriptions
                   Simple queries but executed fast.
            Fast indexing (20 to 60m) of newly “pinged” information
                   Sindice can be thought as a “Spider In the middle” for application
                    2 application semantic communication via published data.




       82
Searching the Web of Data
Digital Enterprise Research Institute                     www.deri.ie




            E.g. search for people who claim to know X




       83
Lod.openlinksoftware.com
Digital Enterprise Research Institute                                 www.deri.ie




            Query service over all the major “linked dataset”
            Advanced queries, (SPARQL, see later)
            No pings
            In general best effort results due to timeouts (on non
             simple queries)




       84
How to manipulate and query RDF?
Digital Enterprise Research Institute                                           www.deri.ie




            Querying Web data on runtime
                   Needs to load RDF data in memory, can be quite slow
            Storing information in RDF-stores and using SPARQL
                   Involves data replication and need to sync between data from the
                    Web and data in your RDF-store
                       – Sindice API to help syncing
                   Lots of RDF-stores available on the market
                       –   Sesame
                       –   Jena
                       –   Openlink Virtuoso
                       –   Allegrograph
                       –   OpenAnzo
                       –   Mulgara, etc


       85
SPARQL
Digital Enterprise Research Institute                                           www.deri.ie




            SPARQL Protocol and RDF Query Language
                   “The SQL of the Semantic Web”
                   Both a protocol and a query language
                       – RDF data can be queried via REST
            Four different query forms
                   SELECT, CONSTRUCT, ASK, DESCRIBE
                   We will mainly focus on the first one
            SPARQL is based on a graph-matching approach
                   Retrieve statements that match some patterns in one (or more)
                    RDF graph(s): independant from serialization
            W3C SPARQL WG currently working on new features
                   http://www.w3.org/2009/01/sparql-charter

       86
SPARQL SELECT
Digital Enterprise Research Institute                                            www.deri.ie




            SELECT all people and their name
                   http://helloopenworld.net/semtech2009/files/select1.sparql


       PREFIX foaf: <http://xmlns.com/foaf/0.1/>
       SELECT ?person ?name
       WHERE {
        ?person a foaf:Person ;
       foaf:name ?name .
       }




       87
SPARQL CONSTRUCT
Digital Enterprise Research Institute                                               www.deri.ie




            Contruct an RDF graph from other ones
            Can be seen as the XSLT of the Semantic Web
                   http://helloopenworld.net/semtech2009/files/construct1.sparql


       PREFIX foaf: <http://xmlns.com/foaf/0.1/>
       PREFIX semtech09: <http://ex.org/semtech09/>
       CONSTRUCT { ?person a semtech09:attendee .}
       WHERE { ?person a foaf:Person . }




       88
SPARQL DESCRIBE
Digital Enterprise Research Institute                                          www.deri.ie




            Get information about a given resource
            DESCRIBE is implementation specific and can return
             different results depending on the triple-store used
                   http://helloopenworld.net/semtech2009/files/desc1.sparql


       DESCRIBE
         <http://helloopenworld.net/semtech2009/data/apassant.r
         df#me>




       89
SPARQL ASK
Digital Enterprise Research Institute                                     www.deri.ie




            Check if a particular pattern matches the RDF graph
            Is Alex a foaf:Person ?
               http://helloopenworld.net/semtech2009/files/ask1.sparql


       PREFIX foaf: http://xmlns.com/foaf/0.1/
       ASK {
         <http://helloopenworld.net/semtech2009/data/apassant.r
         df#me> a foaf:Person . }




       90
SPARQL Protocol
Digital Enterprise Research Institute                                        www.deri.ie




            REST-compliant protocol for SPARQL queries
                   http://helloopenworld.net/semtech2009/store1/?query=PREFIX+f
                    oaf%3A+%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F
                    %3E%0D%0ASELECT+%3Fperson+%3Fname%0D%0AWHER
                    E+{%0D%0A+%3Fperson+a+foaf%3APerson+%3B%0D%0A++
                    +foaf%3Aname+%3Fname+.%0D%0A}%0D%0A&output=htmlta
                    b
                   Easy for remote SPARQL querying




       91
SPARCool.net
Digital Enterprise Research Institute                                               www.deri.ie




            http://sparcool.net
            Run SPARQL queries on any URI thatfollows the Linked
             Data principles
                   http://sparcool.net/j/dbp:abstract;l=en/http://dbpedia.org/resource
                    /Semantic_Web
            Various formats for results (HTML, JSON, etc.)
            Embedresults in your documents using JSONP




       92
Setup a SPARQL endpoint
Digital Enterprise Research Institute                                              www.deri.ie




            Various open-source triple-store availables
                   Virtuoso, Sesame, Joseki …
                   Based on various back-ups (MySQL, dedicated FS …)
            We will focus on xAMP solutions with ARC2
                   Lightweight RDF framework for PHP - http://arc.semsol.org
                   RDF Store based on MySQL
                   Only a few lines of code to set-up a repository
                       – http://helloopenworld.net/semtech2009/store1/index.phps
                   Using SPARQL+ to LOAD / UPDATE / DELETE RDF data
                       – SPARQL being read-only
                   Used in various of our projects
                       – SMOB, LODr, etc


       93
Loading RDF data
Digital Enterprise Research Institute                                               www.deri.ie




            SPARQL is a read-only language
            SPARQL+ allows to add / modify / delete RDF data
                   LOAD <URI> [INTO <URI>]
                   Will load the RDF data from <URI> into the store before going
                    into SPARQL querying
            LOAD your FOAF files in the RDF store
                   http://helloopenworld.net/semtech2009/store1/
                   E.g. LOAD
                    <http://helloopenworld.net/semtech2009/data/apassant.rdf>
                       – NB: To be done in POST mode




       94
Lightweight inference
Digital Enterprise Research Institute                                            www.deri.ie




            ARC2 does not provide RDFS inference engine
                   But triggers can be used to write one
                   http://apassant.net/blog/2008/10/01/lightweight-subpropertyof-
                    subclassof-inference-arc2
            Rule rdfs9: inference on subproperties
                   http://www.w3.org/TR/rdf-mt/#RDFSRules



                   Can be done with SPARQL CONSTRUCT and ARC2 triggers
                   http://helloopenworld.net/semtech2009/store2/index.phps
                   http://helloopenworld.net/semtech2009/files/ARC2_SubPropertyInfe
                    renceTrigger.phps


       95
Lightweight inference
Digital Enterprise Research Institute                                             www.deri.ie




            LOAD your profile in the inference-enabled store
                   http://helloopenworld.net/semtech2009/store2
            Try the following query in both stores
                   Only the second one deals with subProperty inference
                   http://helloopenworld.net/semtech/2009/files/select2.sparql
       PREFIX foaf: <http://xmlns.com/foaf/0.1/>
       SELECT ?person
       WHERE {
       <YOUR_URI>foaf:knows ?person .
       }


       96
Complex triggers
Digital Enterprise Research Institute                                                  www.deri.ie




            LOAD the RDF file corresponding to each user interest
                   Must be done to avoid issues of distributed SPARQL querying
            Trigger designed using SPARQL SELECT + SPARUL
             LOAD
                   For each loaded file, check if there are any foaf:topic_interest
                    and load them into the store
                   http://helloopenworld.net/semtech2009/files/ARC2_InterestLoad
                    Trigger.phps
                   http://helloopenworld.net/semtech2009/store3




       97
SPARQL SELECT w/ Triggers
Digital Enterprise Research Institute                                            www.deri.ie




            Advanced querying capabilities
                   http://helloopenworld.net/semtech2009/files/select3.sparql
       PREFIX foaf: <http://xmlns.com/foaf/0.1/>
       PREFIX dbo: <http://dbpedia.org/ontology/>
       SELECT ?person
       WHERE {
        ?person foaf:topic_interest [
       dbo:director<http://dbpedia.org/resource/Quentin_Tarantino
          >.]
       }


       98
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       99
Mash-ups & Advanced Topics
Digital Enterprise Research Institute                  www.deri.ie




        Applying and extending what we have learned
        Displaying and rendering the Web of Data
        End-user Interaction, UI
        Read/write Web of Data
        Writing Applications!




       100
Exhibit faceted browsing
Digital Enterprise Research Institute                                               www.deri.ie




            Exhibit
                   JavaScript library for faceted browsing
                   http://www.simile-widgets.org/exhibit/
            Can be used directly on the top of a SPARQL endpoint
                   Thanks to SPARQL CONSTRUCT and the Babel translation
                    service
                   http://helloopenworld.net/semtech2009/files/construct2.sparql
                   http://helloopenworld.net/semtech2009/exhibit
                   http://microplanet.sioc-project.org/
                       – With geolocation services




       101
Ubiquity command
Digital Enterprise Research Institute                                    www.deri.ie




            Ubiquity
                   Mozilla Firefox command line for the Web
                   http://ubiquity.mozilla.com/
            Find people that like a given topic when browsing
             Wikipedia
                   (1) Query Dbpedia to find the related URI
                   (2) Query the RDF Store to identify related people
                   Total: 2 SPARQL queries !
                   http://helloopenworld.net/semtech2009/ubiquity
                   http://en.wikipedia.org/wiki/Reservoir_Dogs




       102
Ubiquity command
Digital Enterprise Research Institute   www.deri.ie




       103
Mash-up tools
Digital Enterprise Research Institute                  www.deri.ie




            DERI Pipes, a tool for semantic mashups
                   http://pipes.deri.org




       104
Sig.ma Mashup Maker
Digital Enterprise Research Institute                         www.deri.ie




            Web of data comes together
            In an interactive mashup maker
            Mashups can be embedded or queries programmatically




       105
Geolocation mash-ups
Digital Enterprise Research Institute                              www.deri.ie




            Since data is interlinked, it’s easy to combine it
            Can mix personal and public data, e.g. in organisations




       106
Data directories
Digital Enterprise Research Institute                                    www.deri.ie




            http://doapstore.org
                   A directory of Software projectsdescribedwith DOAP
                   CompletelyRDF-based




       107
Ongoing works
Digital Enterprise Research Institute                                     www.deri.ie




            Enabling the write on the Web of Data
                   “Pushback”
                    http://esw.w3.org/topic/PushBackDataToLegacySources
                   More demos at: http://ld2sd.deri.org/pushback/
                   Check out code at
                    http://code.google.com/p/pushback/ and contribute !
            Using RDFa to automate web forms
                   RDFormshttp://rdfs.org/ns/rdforms




       108
Outline
Digital Enterprise Research Institute      www.deri.ie




        Content
        Motivation
        What is the Web of Data?
        Creating Structured Data
        Discovery, Accessing & Querying
        Mash-ups & Advanced Topics




       109
Conclusion
Digital Enterprise Research Institute                                         www.deri.ie




            Web of Data is a reality
            Tools and technologies exist to
                   Create and describe data on the Web
                   Store and access data on the Web
                   Discover and query data on the Web
                   Build and expand your applications with data on the Web
            Challenges
                   Technical issues such as scalability and usability
                   Social issues (trust, privacy, etc.)
                   Economic issues (building a critical mass)




       110
Events
Digital Enterprise Research Institute                                            www.deri.ie




            LDOW Series
                   http://events.linkeddata.org/
            ESWC and ISWC
                   Major venues for academic research on the Semantic Web
                   SFSW: Scripting For the Semantic Web Workshop
                       – http://www.semanticscripting.org/
            Triplification challenge
                   Applications enabling existing systems being part of the Web of
                    Data
                   http://triplify.org/Challenge/2009
                   Deadline June 30th, 2009



       111
Feedback
Digital Enterprise Research Institute                           www.deri.ie




            Did you learn something during the tutorial ?
            Do you think you can now explain the Web of Data and
             build applications ?
            Which topics that you expected were not covered ?
            Feel free to discuss or contact us
                   alexandre.passant@deri.org
                   giovanni.tummarello@deri.org
                   michael.hausenblas@deri.org
                   #swig on irc.freenode.net




       112

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Hello Open World - Semtech 2009

  • 1. Digital Enterprise Research Institute www.deri.ie Hello Open Data World! The Web of Data for the Pragmatic Developer Alexandre Passant & Giovanni Tummarello SEMTECH, San Jose, California 2009 Copyright 2008 Digital Enterprise Research Institute. All rights reserved.
  • 2. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics NB: Tutorial adapted from the WWW2009 “Hello Open World” presentation by Alexandre Passant and Michael Hausenblas 2
  • 3. Speakers introduction Digital Enterprise Research Institute www.deri.ie  Alexandre Passant  Postdoctoral researcher, DERI Galway  Social Software and Semantic Web  http://apassant.net  Giovanni Tummarello  Research Fellow, DERI Galway  Web of Data Search and Mashups  http://g1o.net 3
  • 4. DERI Galway Digital Enterprise Research Institute www.deri.ie  Enabling Networked Knowledge  Social Semantic Information Spaces  Semantic Reality  Approximately 130 people 4
  • 5. Companion website Digital Enterprise Research Institute www.deri.ie http://helloopenworld.net 5
  • 6. What is this tutorial about Digital Enterprise Research Institute www.deri.ie  What you will learn  Web of Data principles  Architecture principles for applications on the Web of Data  Finding and creating structured data  Using vocabularies and lightweight inference  Querying Web data with SPARQL and with Sindice  User interfaces and mash-ups  What you will not  Ontology mapping and alignment  Advanced rules languages  Complex SPARQL querying 6
  • 7. What you should be able to do after this tutorial Digital Enterprise Research Institute www.deri.ie  Explain the Web of Data to your CTO / Students / Advisor / Grandmother  Spread the values of the Web of Data  Join the Web of Data  Effectively enriching your existing pages and applications with annotations that will help your data to be found and integrated  Leverage the Web of Data for your apps  Finding data “out there” and reusing it  Using open-source and xAMP technologies  Creating, consuming and mashing-up RDF data 7
  • 8. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 8
  • 9. Motivation Digital Enterprise Research Institute www.deri.ie Yahoo Google Rich Snippets 9
  • 10. Motivation Digital Enterprise Research Institute www.deri.ie  More and more data is available on the Web  Structured data, in RDF, microformats, etc.  Reusing Data is a value for your application !  Up to now people would develop against proprietary APIs (such as from Flickr, Google, etc.)  Loss of time for developers  The Web of Data …  Provides a uniform data model (RDF)  Provides a uniform API for accessing data (RDF/SPARQL)  Provide common semantics for this data (RDFS/OWL)  Enables serendipitous usage of data 10
  • 11. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 11
  • 12. What is the Web of Data? Digital Enterprise Research Institute www.deri.ie  Web of information structured via standards and made available on the Web  Microformats and GRDDL  RDF using various serializations: RDF/XML, RDFa, etc. 12
  • 13. RDF Digital Enterprise Research Institute www.deri.ie  RDF: Resource Description Framework  As of RDF abstract syntax, a data model: a directed, labeled graph based on URIs  RDF is not XML !  RDF/XML is only one of the multiple way to serialize RDF data (N3, RDFa …)  Triple: (subject predicate object)  subject  predicate  object <http://sw-app.org/#i><http://xmlns.com/foaf/0.1/knows> <http://apassant.net/alex>. 13
  • 14. RDF Digital Enterprise Research Institute www.deri.ie 14
  • 15. RDF Digital Enterprise Research Institute www.deri.ie @prefix dcterms: <http://purl.org/dc/terms/> . <http://deri.ie/teaching/tutorials/lod-intro> dcterms:title “Tutorial on Linked Data - A Practical Introduction” ; dcterms:author<http://sw-app.org/mic.xhtml#i> ; dcterms:subject <http://dbpedia.org/resource/Linked_Data> . 15
  • 16. “Semantic Data” on the Web Digital Enterprise Research Institute www.deri.ie  Web of Data == the Semantic Web?  Not really, it’s the “Web” facing part of it  It’s part of it, a kind of subset  In contrast to the full-fledged Semantic Web vision, the Web of Data more about raw data publishing in interoperable format than about logic inference and reasoning on it 16
  • 17. What is the Web of Data? Digital Enterprise Research Institute www.deri.ie 17
  • 18. Web of data via “Linked Data” Digital Enterprise Research Institute www.deri.ie  Linked data principles, by Tim Berners-Lee, ca. 2006  Use URIs to identify things (anything, not just documents) – “To benefit from and increase the value of the World Wide Web, agents should provide URIs as identifiers for resources” – http://www.w3.org/TR/webarch/  Use HTTP URIs – globally unique names, distributed ownership – allows people to look up things  Provide useful information in RDF – when someone looks up a URI  Include RDF links to other URIs– to enable discovery of related information  Example http://dbpedia.org/resource/Dublin 18
  • 19. Linked data growth Digital Enterprise Research Institute www.deri.ie 2007 2008 19
  • 20. Linked data growth Digital Enterprise Research Institute www.deri.ie 2008 2009 20
  • 21. Needed: shared vocabularies (Ontologies) Digital Enterprise Research Institute www.deri.ie  Ontologies provide common semantics for the Web of Data  “An ontology is a specification of a conceptualization.”  Main languages are RDFS and OWL  This tutorial will mainly focus on RDFS  OWL allows advanced axioms (contraints, unions …)  Classes and properties  :Person a rdfs:Class  :father a rdfs:Property  :father rdfs:domain :Person  :father rdfs:range :Person 21
  • 22. Ontologies Digital Enterprise Research Institute www.deri.ie  Hierarchies in ontologies  Are needed to define narrower / broader concepts  :LivingThing > :Person  Can be applied to both classes and properties  :Person rdfs:subClassOf :LivingThing  :father rdfs:subPropertyOf :familyRelation  Inference engines can take advantage of it to create new facts  Can be used when querying information  Retrieve all :LivingThing instances with a :familyRelation – Will get :Person and :father ! 22
  • 23. Notable ontologies Digital Enterprise Research Institute www.deri.ie  Social networks and social data  FOAF – Friend Of A Friend  SIOC – Semantically-Interlinked Online Communities  Software development  DOAP – Description Of A Project  BEATLE - Bug And Enhancement Tracking LanguagE  Comprehensive / Top-level  Yago (From Wikipedia)  OpenCYC  Taxonomies  SKOS – Simple Knowledge Organisation System 23
  • 24. Zooming in: FOAF Ontology Digital Enterprise Research Institute www.deri.ie  A model to describe people and social networks  http://foaf-project.org  Concepts  Person, OnlineAccount, Document, etc.  Properties  name, homepage, holdsAccount, knows, etc. 24
  • 25. FOAF in use Digital Enterprise Research Institute www.deri.ie  Google Social Graph API  http://code.google.com/intl/fr/apis/socialgraph/  Uses FOAF information already there on the Web to find your contacts  http://socialgraph- resources.googlecode.com/svn/trunk/samples/findcontacts.html  E.g.: http://apassant.net – http://socialgraph- resources.googlecode.com/svn/trunk/samples/findcontacts.html?q= http%3A%2F%2Fapassant.net – Contacts found in various FOAF files that link to myself and to my profile 25
  • 26. Zooming in: SIOC Ontology Digital Enterprise Research Institute www.deri.ie  Describe Web communities and their social interactions  Who’s writing what, who’s answering who, etc.  A simple model to ensure easy-integration into existing applications  Lightweight: one core ontology, 4 modules  Plug-ins /core-feature for several CMS  Drupal, Wordpress etc.  Enables interoperability between social applications  http://sioc-project.org 26
  • 27. The SIOC ontology Digital Enterprise Research Institute www.deri.ie  The main classes and properties are: 27
  • 28. Combining FOAF + SIOC Digital Enterprise Research Institute www.deri.ie 28
  • 29. Adoption of SIOC Digital Enterprise Research Institute www.deri.ie 29
  • 30. Which ontologies to use ? Digital Enterprise Research Institute www.deri.ie  SearchMonkey Vocabularies  http://developer.yahoo.com/searchmonkey/smguide/profile_voca b.html 30
  • 31. Which ontologies to use ? Digital Enterprise Research Institute www.deri.ie  How to Publish Linked Data on the Web  http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/ 31
  • 32. Extending ontologies ? Digital Enterprise Research Institute www.deri.ie  What if existing ontologies are not enough for your needs ?  Create a new one  … or extend existing ones !  Ontologies can be extended in a decentralized way  E.g. you can create a subproperty of foaf:knows, “attendedTutorialWith”, in your own ontology  Publish in on your own  Or use http://open.vocab.org 32
  • 33. Attention: Domain and range Digital Enterprise Research Institute www.deri.ie  Domain and range of properties are descriptive, not prescriptive  Example if we say :father rdfs:domain :Person – Not only pre-defined Persons can be fathers – But every father is a Person !  Consequence 1: One triple is enough to describe several informations  Consequence 2: DON’T use foaf:homepage for a shoe  For details  Based on RDF semantics (Rule rdfs2)  http://www.w3.org/TR/rdf-mt/ 33
  • 34. Linking Open Data Project Digital Enterprise Research Institute www.deri.ie  Community project with W3C support started in early 2007 [LOD]: http://linkeddata.org  Idea: take existing (open) data sets and make them available on the Web in RDF  Interlink them with other data sets  Expand the network effect of Linked Data !  Raw Data Now !  Tim Berners-Lee TED talk  http://www.ted.com/index.php/talks/tim_berners_lee_on_the_nex t_web.html Kudos to Tom Heath and Richard Cyganiak; the material in this section is heavily based on their work. 34
  • 35. Linking Open Data Project Digital Enterprise Research Institute www.deri.ie May 2007 35
  • 36. Linking Open Data Project Digital Enterprise Research Institute www.deri.ie Feb 2009 36
  • 37. Notable datasets of the LOD cloud Digital Enterprise Research Institute www.deri.ie  Linking Open Data  Community project started in 2007 - http://linkeddata.org  Dbpedia – http://dbpedia.org  Wikipedia in RDF: “more than 2.6 million things, including at least 213,000 persons, 328,000 places, 57,000 music albums, 36,000 films, 20,000 companies”  Geonames – http://geonames.org  “over eight million geographical names”: coordinates, etc.  Freebase - http://rdf.freebase.com/  “5203825 Topics 14110006 Named Entities”  E.g. http://rdf.freebase.com/rdf/en.blade_runner 37
  • 38. Linking Open Data Project Digital Enterprise Research Institute www.deri.ie DBpedia 38
  • 39. Linking Open Data Project Digital Enterprise Research Institute www.deri.ie Geonames 39
  • 40. Querying dbpedia Digital Enterprise Research Institute www.deri.ie  Programmatically (via SPARQL, see later)  Via User Interface  http://wikipedia.aksw.org 40
  • 41. Tools and Applications Digital Enterprise Research Institute www.deri.ie  Linking Open Data homepage [LOD] has  Browsing with Tabulator, VisiNav, Sig.ma, DBpedia Mobile, iLOD, etc.  Searching with Sindice, SWSE, Falcons, etc.  Mashups, e.g. Revyu, BBC Music, DERI Pipes  See further http://esw.w3.org/topic/SweoIG/TaskForces/Community Projects/LinkingOpenData/Applications 41
  • 42. Tools and Applications Digital Enterprise Research Institute www.deri.ie DBpedia Mobile 42
  • 43. Applications integration Digital Enterprise Research Institute www.deri.ie BBC music beta 43
  • 44. Typical architectures of applications for the Web of Data (1/2) Digital Enterprise Research Institute www.deri.ie from: Heitmann, B., et al., “Towards a reference architecture for Semantic Web applications,” Proceedings of the 1st Int. Web Science Conference, 2009 44
  • 45. Typical architectures of applications for the Web of Data (2/2) Digital Enterprise Research Institute www.deri.ie  Data Interface: Abstraction layer regarding implementation, number and distribution of persistence layers.  Persistence Layer: Persistent storage of data and run time state.  User Interface: Human accessible interface for using application and viewing data. (“read-only”)  Annotation User Interface: Edit, create, import or export data.  Integration Service: Merge Structure, Syntax or Semantics of data from multiple heterogeneous sources.  Search Engine: Search on content or semantic features.  Crawler: Retrieval of remote data for integration service. 45
  • 46. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 46
  • 47. Creating Structured Data Digital Enterprise Research Institute www.deri.ie  Overview of different methods:  Create RDF/XML manually (using your favourite text-editor or Web-based interfaces)  Create XHTML+RDFa documents and use GRDDL transformation – For both human and machines !  Use exporters / wrappers for existing service  Use applications that natively expose RDF data  Provide mappings from RDBMS to RDF data  Hands-on !  We will go through several of them to create interlinked RDF data from various sources of structured data 47
  • 48. Getting a FOAF profile Digital Enterprise Research Institute www.deri.ie  Or how to give yourself a URI  Be part of the Web of Data  Create your FOAF file  http://www.ldodds.com/foaf/foaf-a-matic (requires hosting - provided during the tutorial)  http://foafbuilder.qdos.com/builder/ (requires OpenID)  I already have an homepage, what about duplication of information ?  Use RDFa to embed RDF annotations in yourhomepage !  More on thistopic in a few slides 48
  • 49. Extend your FOAF profile Digital Enterprise Research Institute www.deri.ie  The foaf:knows property aims to represent social connections between people  :alex foaf:knows :michael  Going further with the relationship vocabulary  http://vocab.org/relationship/: colleagueOf, hasMet …  Add some people from the workshop, validate, and upload to the workshop repository  http://www.w3.org/RDF/Validator/  http://helloopenworld.net/semtech09/data  You finally got a URI ! – http://helloopenworld.net/semtech09/data/apassant.rdf#me 49
  • 50. Defining personal interests Digital Enterprise Research Institute www.deri.ie  Instead of modeling interests as plain-text strings, use URIs to describe them !  Allows interlinking of various resources for advanced query purposes: “find all people that like movies directed by Tarantino”  And link them to you using foaf:topic_interest  :me foaf:topic_interest :movie  But … where to get these URIs ?  The Linking Open Data cloud ! – Provide URIs for million of concepts, esp. thanks to DBpedia  Sindice can be used to find URIs for a given concept – http://sindice.com 50
  • 51. Defining personal interests Digital Enterprise Research Institute www.deri.ie 51
  • 52. Defining personal interests Digital Enterprise Research Institute www.deri.ie 52
  • 53. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  GRDDL is a mechanism to transform any kind of XML to RDF  XHTML+RDFa is XML, hence GRDDL can extract it  Simply embeds RDFa annotations in your HTML code  Indexed by Yahoo! SearchMonkey and Google  Done via XSLT, available at http://www.w3.org/2008/07/rdfa-xslt 53
  • 54. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  The GRDDL Primer athttp://www.w3.org/TR/grddl- primer/#scheduling shows the overall processing of XHTML+RDFa: 54
  • 55. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  http://sdow2009.semanticweb.org 55
  • 56. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  http://sdow2009.semanticweb.org  Browse source to check RDFa annotations 56
  • 57. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  http://sdow2009.semanticweb.org  Header contains prefixes and links to the GRDDL transformation 57
  • 58. RDFa and GRDDL Digital Enterprise Research Institute www.deri.ie  http://sdow2009.semanticweb.org  Webpage can be translated to native RDF/XML using an RDFa distiller - http://www.w3.org/2007/08/pyRdfa/ 58
  • 59. AddRDFa to yourhomepage Digital Enterprise Research Institute www.deri.ie  Choose the right DTD  http://www.w3.org/TR/rdfa-syntax/DTD/xhtml-rdfa-1.dtd  Addprefixesdefinition in the header  Depending on ontologies youwill use  Addappropriate profile  E.g. http://ns.inria.fr/grddl/rdfa/  Addaditionalmarkup  E.g. rel, about, typeof  Example  http://helloopenworld.net/semtech2009/files/profile.html 59
  • 60. Wrappers for existing sources Digital Enterprise Research Institute www.deri.ie  Creating and maintaining a FOAF file by hand can be a time-consuming task  How can we automatically get RDF data from existing sources ?  What about Web 2.0 services in which we already give lots of personal information ?  Most of them provide APIs to get structured information (JSON, XML …) about the user profiles, content, etc.  API to RDF wrappers can easily be implemented 60
  • 61. Wrappers for Web 2.0 services Digital Enterprise Research Institute www.deri.ie  Facebook wrapper  Generates a FOAF file from your Facebook profile  http://www.dcs.shef.ac.uk/~mrowe/foafgenerator.html  Flickr wrapper  Generates FOAF + SIOC + links to geographical information (using geonames.org)  http://apassant.net/home/2007/12/flickrdf 61
  • 62. RDFification services Digital Enterprise Research Institute www.deri.ie  Translates many structured sources into RDF  URIBurner – http://linkeddata.uriburner.com/ – Open Source, C++ , Based on Virtuoso  Any23 – Sindice sponsored – Open Source, Java based  Swignition – http://buzzword.org.uk/swignition/ – Perl based  Triplr – Purelysyntactic, fast – http://triplr.org 62
  • 63. Interlinking identities Digital Enterprise Research Institute www.deri.ie  The previous exporters create different URIs  A need to unify your online identity on the Web of Data  owl:sameAs  Used to state that two resources with different URIs are about the same entitiy  http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/  owl:InverseFunctionalProperty  foaf:mbox, foaf:openid, etc.  “Inverse Functional” properties can be used to identify uniqueness for a foaf:Person 63
  • 64. Interlinking identities and networks Digital Enterprise Research Institute www.deri.ie 64
  • 65. Native export of RDF data Digital Enterprise Research Institute www.deri.ie  CMS can expose RDF data natively using dedicated plug-ins  SIOC Export for Drupal: http://drupal.org/project/SIOC  Provide RDF export of each blog post – http://apassant.net/blog/2009/03/07/call-suggested-features-sparql- working-group – http://apassant.net/sioc/node/235  Using RDF autodiscovery feature in the HTML header – So that RDF can be discovered when browsing HTML – Semantic Radar: http://sioc-project.org/firefox  RDFa to be included in Drupal7 core ! – http://groups.drupal.org/node/16597 – 100.000’s of RDFa-powered websites 65
  • 66. Overview: SIOC for vBulletin Digital Enterprise Research Institute www.deri.ie 66
  • 67. Relational to RDF Mapping Digital Enterprise Research Institute www.deri.ie  Relational data (RDB) is structured data and can be mapped to RDF straight-forward  Main issues:  Closed-world vs. open-world modeling  Assigning URIs for entities (records)  Mapping language expressivity  For a state-of-the-art see http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_Su rveyReport.pdf 67
  • 68. Relational to RDF Mapping Digital Enterprise Research Institute www.deri.ie  Standardization  W3C RDB2RDF Incubator Group 2008/2009  Upcoming W3C RDB2RDF Working Group  Current solutions (see state-of-the-art)  D2RQ – http://www4.wiwiss.fu-berlin.de/bizer/d2rq/ – DBLP in RDF: http://dblp.l3s.de/d2r/  OpenLink’s Virtuoso – http://www.openlinksw.com/virtuoso/  Triplify – http://triplify.org 68
  • 69. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 69
  • 70. Discovery of RDF data Digital Enterprise Research Institute www.deri.ie  Discovery is the process of starting with a URI and learn more about the resources that can be accessed or described through it  .. Without using a search engine 70
  • 71. Discovering RDF data Digital Enterprise Research Institute www.deri.ie  Simple case: Dereference  “Follow-Your-Nose” approach  Semantic Sitemaps  to find SPARQL endpoints or data dumps http://sw.deri.org/2007/07/sitemapextension/  Links from within the RDF  voiD, vocabulary of interlinked datasets – Allows to learn what a dataset is about – Provides quantitative data on interlinking (statistics) – Enables to deliver licensing, provenance and access information – http://semanticweb.org/wiki/VoiD  SeeAlso, owl:import or simply dereference other URIs 71
  • 72. Semantic Web Sitemaps Digital Enterprise Research Institute www.deri.ie  Easy to create metadata from your existing database (D2RQ, microformats etc)  But you need to tell the world about it!  More is needed to make your data useful (e.g. linking to OTHER URIs if your entities are not something completely “yours”)  Need to make the world know your data is there.  Semantic Web Sitemaps can help 72
  • 73. Large quantities of linked data: how to expose? Digital Enterprise Research Institute www.deri.ie  The fact that the data is HTTP retrievable in small bits makes it crawlable.  But data producers are very scared of this:  Million of hits for each refresh  And clearly something better must be possible  Most data producers do in fact already provide full dumps of the base data  Or SPARQL endpoints 73
  • 74. Extending Sitemaps to expose data Digital Enterprise Research Institute www.deri.ie  Sitemaps:  Originally by Google, immediately adopted by all (Yahoo, MSN) etc  Expose the “deep web”, by providing a list of pages “to be crawled”  Written in XML, Linked directly in the robot.txt Example: <?xml version="1.0" encoding="UTF-8"?> < urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> < url> < loc>http://www.example.com/</loc> < lastmod>2005-01-01</lastmod> < changefreq>monthly</changefreq> < priority>0.8</priority> </url> </urlset> 74
  • 75. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 75
  • 76. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 76
  • 77. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 77
  • 78. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 78
  • 79. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 79
  • 80. The Semantic Sitemap Extention Digital Enterprise Research Institute www.deri.ie Example first: <urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:sc="http://sw.deri.org/2007/07/sitemapextension/scschema.xsd"> <sc:dataset> <sc:datasetLabel>Product Catalog for Example.org</sc:datasetLabel> <sc:dataDumpLocation>http://example.org/cataloguedump.rdf </sc:dataDumpLocation> <sc:linkedDataPrefix>http://example.org/products/</sc:linkedDataPrefix> <changefreq>monthly</changefreq> </sc:dataset> </urlset> 80
  • 81. How it is meant to be used Digital Enterprise Research Institute www.deri.ie  As a crawler  If you are given a URL for an RDF site check for the sitemap  If a dump is available, download that instead  As a client  If you have a dump, and want an update  Check the sitemap, to locate it in case it has changed position  Or to locate a SPARQL endpoint 81
  • 82. Or Search! Digital Enterprise Research Institute www.deri.ie  Sindice Search Engine  http://sindice.com  Look up by RDF by keywords and on property/value descriptions  Simple queries but executed fast.  Fast indexing (20 to 60m) of newly “pinged” information  Sindice can be thought as a “Spider In the middle” for application 2 application semantic communication via published data. 82
  • 83. Searching the Web of Data Digital Enterprise Research Institute www.deri.ie  E.g. search for people who claim to know X 83
  • 84. Lod.openlinksoftware.com Digital Enterprise Research Institute www.deri.ie  Query service over all the major “linked dataset”  Advanced queries, (SPARQL, see later)  No pings  In general best effort results due to timeouts (on non simple queries) 84
  • 85. How to manipulate and query RDF? Digital Enterprise Research Institute www.deri.ie  Querying Web data on runtime  Needs to load RDF data in memory, can be quite slow  Storing information in RDF-stores and using SPARQL  Involves data replication and need to sync between data from the Web and data in your RDF-store – Sindice API to help syncing  Lots of RDF-stores available on the market – Sesame – Jena – Openlink Virtuoso – Allegrograph – OpenAnzo – Mulgara, etc 85
  • 86. SPARQL Digital Enterprise Research Institute www.deri.ie  SPARQL Protocol and RDF Query Language  “The SQL of the Semantic Web”  Both a protocol and a query language – RDF data can be queried via REST  Four different query forms  SELECT, CONSTRUCT, ASK, DESCRIBE  We will mainly focus on the first one  SPARQL is based on a graph-matching approach  Retrieve statements that match some patterns in one (or more) RDF graph(s): independant from serialization  W3C SPARQL WG currently working on new features  http://www.w3.org/2009/01/sparql-charter 86
  • 87. SPARQL SELECT Digital Enterprise Research Institute www.deri.ie  SELECT all people and their name  http://helloopenworld.net/semtech2009/files/select1.sparql PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?person ?name WHERE { ?person a foaf:Person ; foaf:name ?name . } 87
  • 88. SPARQL CONSTRUCT Digital Enterprise Research Institute www.deri.ie  Contruct an RDF graph from other ones  Can be seen as the XSLT of the Semantic Web  http://helloopenworld.net/semtech2009/files/construct1.sparql PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX semtech09: <http://ex.org/semtech09/> CONSTRUCT { ?person a semtech09:attendee .} WHERE { ?person a foaf:Person . } 88
  • 89. SPARQL DESCRIBE Digital Enterprise Research Institute www.deri.ie  Get information about a given resource  DESCRIBE is implementation specific and can return different results depending on the triple-store used  http://helloopenworld.net/semtech2009/files/desc1.sparql DESCRIBE <http://helloopenworld.net/semtech2009/data/apassant.r df#me> 89
  • 90. SPARQL ASK Digital Enterprise Research Institute www.deri.ie  Check if a particular pattern matches the RDF graph  Is Alex a foaf:Person ?  http://helloopenworld.net/semtech2009/files/ask1.sparql PREFIX foaf: http://xmlns.com/foaf/0.1/ ASK { <http://helloopenworld.net/semtech2009/data/apassant.r df#me> a foaf:Person . } 90
  • 91. SPARQL Protocol Digital Enterprise Research Institute www.deri.ie  REST-compliant protocol for SPARQL queries  http://helloopenworld.net/semtech2009/store1/?query=PREFIX+f oaf%3A+%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F %3E%0D%0ASELECT+%3Fperson+%3Fname%0D%0AWHER E+{%0D%0A+%3Fperson+a+foaf%3APerson+%3B%0D%0A++ +foaf%3Aname+%3Fname+.%0D%0A}%0D%0A&output=htmlta b  Easy for remote SPARQL querying 91
  • 92. SPARCool.net Digital Enterprise Research Institute www.deri.ie  http://sparcool.net  Run SPARQL queries on any URI thatfollows the Linked Data principles  http://sparcool.net/j/dbp:abstract;l=en/http://dbpedia.org/resource /Semantic_Web  Various formats for results (HTML, JSON, etc.)  Embedresults in your documents using JSONP 92
  • 93. Setup a SPARQL endpoint Digital Enterprise Research Institute www.deri.ie  Various open-source triple-store availables  Virtuoso, Sesame, Joseki …  Based on various back-ups (MySQL, dedicated FS …)  We will focus on xAMP solutions with ARC2  Lightweight RDF framework for PHP - http://arc.semsol.org  RDF Store based on MySQL  Only a few lines of code to set-up a repository – http://helloopenworld.net/semtech2009/store1/index.phps  Using SPARQL+ to LOAD / UPDATE / DELETE RDF data – SPARQL being read-only  Used in various of our projects – SMOB, LODr, etc 93
  • 94. Loading RDF data Digital Enterprise Research Institute www.deri.ie  SPARQL is a read-only language  SPARQL+ allows to add / modify / delete RDF data  LOAD <URI> [INTO <URI>]  Will load the RDF data from <URI> into the store before going into SPARQL querying  LOAD your FOAF files in the RDF store  http://helloopenworld.net/semtech2009/store1/  E.g. LOAD <http://helloopenworld.net/semtech2009/data/apassant.rdf> – NB: To be done in POST mode 94
  • 95. Lightweight inference Digital Enterprise Research Institute www.deri.ie  ARC2 does not provide RDFS inference engine  But triggers can be used to write one  http://apassant.net/blog/2008/10/01/lightweight-subpropertyof- subclassof-inference-arc2  Rule rdfs9: inference on subproperties  http://www.w3.org/TR/rdf-mt/#RDFSRules  Can be done with SPARQL CONSTRUCT and ARC2 triggers  http://helloopenworld.net/semtech2009/store2/index.phps  http://helloopenworld.net/semtech2009/files/ARC2_SubPropertyInfe renceTrigger.phps 95
  • 96. Lightweight inference Digital Enterprise Research Institute www.deri.ie  LOAD your profile in the inference-enabled store  http://helloopenworld.net/semtech2009/store2  Try the following query in both stores  Only the second one deals with subProperty inference  http://helloopenworld.net/semtech/2009/files/select2.sparql PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?person WHERE { <YOUR_URI>foaf:knows ?person . } 96
  • 97. Complex triggers Digital Enterprise Research Institute www.deri.ie  LOAD the RDF file corresponding to each user interest  Must be done to avoid issues of distributed SPARQL querying  Trigger designed using SPARQL SELECT + SPARUL LOAD  For each loaded file, check if there are any foaf:topic_interest and load them into the store  http://helloopenworld.net/semtech2009/files/ARC2_InterestLoad Trigger.phps  http://helloopenworld.net/semtech2009/store3 97
  • 98. SPARQL SELECT w/ Triggers Digital Enterprise Research Institute www.deri.ie  Advanced querying capabilities  http://helloopenworld.net/semtech2009/files/select3.sparql PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX dbo: <http://dbpedia.org/ontology/> SELECT ?person WHERE { ?person foaf:topic_interest [ dbo:director<http://dbpedia.org/resource/Quentin_Tarantino >.] } 98
  • 99. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 99
  • 100. Mash-ups & Advanced Topics Digital Enterprise Research Institute www.deri.ie  Applying and extending what we have learned  Displaying and rendering the Web of Data  End-user Interaction, UI  Read/write Web of Data  Writing Applications! 100
  • 101. Exhibit faceted browsing Digital Enterprise Research Institute www.deri.ie  Exhibit  JavaScript library for faceted browsing  http://www.simile-widgets.org/exhibit/  Can be used directly on the top of a SPARQL endpoint  Thanks to SPARQL CONSTRUCT and the Babel translation service  http://helloopenworld.net/semtech2009/files/construct2.sparql  http://helloopenworld.net/semtech2009/exhibit  http://microplanet.sioc-project.org/ – With geolocation services 101
  • 102. Ubiquity command Digital Enterprise Research Institute www.deri.ie  Ubiquity  Mozilla Firefox command line for the Web  http://ubiquity.mozilla.com/  Find people that like a given topic when browsing Wikipedia  (1) Query Dbpedia to find the related URI  (2) Query the RDF Store to identify related people  Total: 2 SPARQL queries !  http://helloopenworld.net/semtech2009/ubiquity  http://en.wikipedia.org/wiki/Reservoir_Dogs 102
  • 103. Ubiquity command Digital Enterprise Research Institute www.deri.ie 103
  • 104. Mash-up tools Digital Enterprise Research Institute www.deri.ie  DERI Pipes, a tool for semantic mashups  http://pipes.deri.org 104
  • 105. Sig.ma Mashup Maker Digital Enterprise Research Institute www.deri.ie  Web of data comes together  In an interactive mashup maker  Mashups can be embedded or queries programmatically 105
  • 106. Geolocation mash-ups Digital Enterprise Research Institute www.deri.ie  Since data is interlinked, it’s easy to combine it  Can mix personal and public data, e.g. in organisations 106
  • 107. Data directories Digital Enterprise Research Institute www.deri.ie  http://doapstore.org  A directory of Software projectsdescribedwith DOAP  CompletelyRDF-based 107
  • 108. Ongoing works Digital Enterprise Research Institute www.deri.ie  Enabling the write on the Web of Data  “Pushback” http://esw.w3.org/topic/PushBackDataToLegacySources  More demos at: http://ld2sd.deri.org/pushback/  Check out code at http://code.google.com/p/pushback/ and contribute !  Using RDFa to automate web forms  RDFormshttp://rdfs.org/ns/rdforms 108
  • 109. Outline Digital Enterprise Research Institute www.deri.ie  Content  Motivation  What is the Web of Data?  Creating Structured Data  Discovery, Accessing & Querying  Mash-ups & Advanced Topics 109
  • 110. Conclusion Digital Enterprise Research Institute www.deri.ie  Web of Data is a reality  Tools and technologies exist to  Create and describe data on the Web  Store and access data on the Web  Discover and query data on the Web  Build and expand your applications with data on the Web  Challenges  Technical issues such as scalability and usability  Social issues (trust, privacy, etc.)  Economic issues (building a critical mass) 110
  • 111. Events Digital Enterprise Research Institute www.deri.ie  LDOW Series  http://events.linkeddata.org/  ESWC and ISWC  Major venues for academic research on the Semantic Web  SFSW: Scripting For the Semantic Web Workshop – http://www.semanticscripting.org/  Triplification challenge  Applications enabling existing systems being part of the Web of Data  http://triplify.org/Challenge/2009  Deadline June 30th, 2009 111
  • 112. Feedback Digital Enterprise Research Institute www.deri.ie  Did you learn something during the tutorial ?  Do you think you can now explain the Web of Data and build applications ?  Which topics that you expected were not covered ?  Feel free to discuss or contact us  alexandre.passant@deri.org  giovanni.tummarello@deri.org  michael.hausenblas@deri.org  #swig on irc.freenode.net 112