Hello Open World - Semtech 2009

Copyright 2008 Digital Enterprise Research Institute. All rights reserved.

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


Outline

Content

Motivation

What is the Web of Data?

Creating Structured Data

Discovery, Accessing & Querying

Mash-ups & Advanced Topics

2

NB: Tutorial adapted from the WWW2009 “Hello Open

World” presentation by Alexandre Passant and Michael

Hausenblas


Speakers introduction

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

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http://apassant.net/

http://g1o.net/


DERI Galway

Enabling Networked Knowledge

Social Semantic Information Spaces

Semantic Reality

Approximately 130 people

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Companion website

http://helloopenworld.net

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http://helloopenworld.net


What is this tutorial about

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

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What you should be able to do after this

tutorial

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

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Outline

Content

Motivation





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Motivation

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Yahoo

Google

Rich

Snippets


Motivation

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

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Outline

Content

Motivation





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Web of information structured via standards and made

available on the Web

Microformats and GRDDL

RDF using various serializations: RDF/XML, RDFa, etc.

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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>.

http://www.w3.org/TR/rdf-concepts/

http://sw-app.org/

http://sw-app.org/

http://sw-app.org/

http://xmlns.com/foaf/0.1/knows

http://apassant.net/alex


RDF

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RDF

@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> .

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“Semantic Data” on the Web

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

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Web of data via “Linked Data”

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

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http://www.w3.org/DesignIssues/LinkedData.html

http://www.w3.org/TR/webarch/

http://dbpedia.org/resource/Dublin


Linked data growth

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2008

2007


Linked data growth

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2009

2008


Needed: shared vocabularies (Ontologies)

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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

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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 !

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Notable ontologies

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

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Zooming in: FOAF Ontology

A model to describe people and social networks

http://foaf-project.org

Concepts

Person, OnlineAccount, Document, etc.

Properties

name, homepage, holdsAccount, knows, etc.

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FOAF in use

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

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http://code.google.com/intl/fr/apis/socialgraph/

http://socialgraph-resources.googlecode.com/svn/trunk/samples/findcontacts.html



http://apassant.net

http://socialgraph-resources.googlecode.com/svn/trunk/samples/findcontacts.html?q=http://apassant.net





Zooming in: SIOC Ontology

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

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The SIOC ontology

The main classes and properties are:

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Combining FOAF + SIOC


Adoption of SIOC

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Which ontologies to use ?

SearchMonkey Vocabularies

http://developer.yahoo.com/searchmonkey/smguide/profile_voca

b.html

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http://developer.yahoo.com/searchmonkey/smguide/profile_vocab.html

http://developer.yahoo.com/searchmonkey/smguide/profile_vocab.html


Which ontologies to use ?

How to Publish Linked Data on the Web

http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/

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Extending ontologies ?

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

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http://open.vocab.org


Attention: Domain and range

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/

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Linking Open Data Project

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

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Kudos to Tom Heath and Richard Cyganiak; the material in

this section is heavily based on their work.

http://linkeddata.org

http://www.ted.com/index.php/talks/tim_berners_lee_on_the_next_web.html

http://www.ted.com/index.php/talks/tim_berners_lee_on_the_next_web.html



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May 2007



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Feb 2009


Notable datasets of the LOD cloud

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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

http://linkeddata.org

http://dbpedia.org

http://geonames.org

http://rdf.freebase.com/

http://rdf.freebase.com/rdf/en.blade_runner



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DBpedia



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Geonames


Querying dbpedia

Programmatically (via SPARQL, see later)

Via User Interface

http://wikipedia.aksw.org

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Tools and Applications

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

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http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData/Applications




Tools and Applications

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DBpedia Mobile


Applications integration

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BBC music beta


Typical architectures of applications

for the Web of Data (1/2)

from: Heitmann, B., et al., “Towards a reference architecture for Semantic Web

applications,” Proceedings of the 1st Int. Web Science Conference, 2009

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Typical architectures of applications

for the Web of Data (2/2)

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.

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Outline

Content

Motivation





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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

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Getting a FOAF profile

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

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http://www.ldodds.com/foaf/foaf-a-matic





http://foafbuilder.qdos.com/builder/


Extend your FOAF profile

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

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http://vocab.org/relationship/

http://www.w3.org/RDF/Validator/

http://helloopenworld.net/www09/data

http://helloopenworld.net/www09/apassant.rdf


Defining personal interests

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

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http://sindice.com



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RDFa and GRDDL

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

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http://www.w3.org/2008/07/rdfa-xslt





RDFa and GRDDL

The GRDDL Primer athttp://www.w3.org/TR/grddl-

primer/#scheduling shows the overall processing of

XHTML+RDFa:

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http://www.w3.org/TR/grddl-primer/




RDFa and GRDDL

http://sdow2009.semanticweb.org

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RDFa and GRDDL


Browse source to check RDFa annotations

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RDFa and GRDDL


Header contains prefixes and links to the GRDDL transformation

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RDFa and GRDDL


Webpage can be translated to native RDF/XML using an RDFa

distiller - http://www.w3.org/2007/08/pyRdfa/

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http://www.w3.org/2007/08/pyRdfa/


AddRDFa to yourhomepage

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

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http://ns.inria.fr/grddl/rdfa/

http://helloopenworld.net/semtech2009/files/profile.html


Wrappers for existing sources

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

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Wrappers for Web 2.0 services

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

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http://www.dcs.shef.ac.uk/~mrowe/foafgenerator.html

http://apassant.net/home/2008/11/flickrdf


RDFification services

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

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http://linkeddata.uriburner.com/about/rdf/http:/twitter.com/terraces

http://buzzword.org.uk/swignition/

http://triplr.org


Interlinking identities

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


owl:InverseFunctionalProperty

foaf:mbox, foaf:openid, etc.

“Inverse Functional” properties can be used to identify uniqueness for a foaf:Person

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Interlinking identities and networks

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Native export of RDF data

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

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http://drupal.org/project/SIOC

http://apassant.net/blog/2009/03/07/call-suggested-features-sparql-working-group











http://apassant.net/sioc/node/235

http://sioc-project.org/firefox



http://groups.drupal.org/node/16597


Overview: SIOC for vBulletin

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Relational to RDF Mapping

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

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http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf

http://www.w3.org/2005/Incubator/rdb2rdf/RDB2RDF_SurveyReport.pdf


Relational to RDF Mapping

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

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http://www4.wiwiss.fu-berlin.de/bizer/d2rq/



http://dblp.l3s.de/d2r/

http://www.openlinksw.com/virtuoso/

http://triplify.org


Outline

Content

Motivation





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Discovery of RDF data

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

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Discovering RDF data

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

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http://semanticweb.org/wiki/VoiD

http://semanticweb.org/wiki/VoiD


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Semantic Web Sitemaps

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


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Large quantities of linked data: how to

expose?

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


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Extending Sitemaps to expose data

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>


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The Semantic Sitemap Extention

Example first:

<urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9http://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>


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Example first:



<sc:dataset>




</sc:dataset>

</urlset>


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Example first:



<sc:dataset>




</sc:dataset>

</urlset>


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Example first:



<sc:dataset>




</sc:dataset>

</urlset>


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Example first:



<sc:dataset>




</sc:dataset>

</urlset>


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Example first:



<sc:dataset>




</sc:dataset>

</urlset>


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How it is meant to be used

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


Or Search!

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.

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http://sindice.com/

http://www.sindice.com/


Searching the Web of Data

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

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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)

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Lod.openlinksoftware.com


How to manipulate and query RDF?

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

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SPARQL

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

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SPARQL SELECT

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 .

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http://helloopenworld.net/www2009/files/q1.sparql


SPARQL CONSTRUCT

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 semtech09: <http://ex.org/semtech09/>

CONSTRUCT ?person a semtech09:attendee .

WHERE ?person a foaf:Person .

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http://helloopenworld.net/www2009/files/construct1.sparql


SPARQL DESCRIBE

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>

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http://helloopenworld.net/www2009/files/desc1.sparql

http://helloopenworld.net/www2009/data/apassant.rdf

http://helloopenworld.net/www2009/data/apassant.rdf


SPARQL ASK

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 .

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http://helloopenworld.net/www2009/files/ask1.sparql

http://xmlns.com/foaf/0.1/


SPARQL Protocol

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

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http://helloopenworld.net/www2009/store1/?query=PREFIX+foaf:+<http://xmlns.com/foaf/0.1/> SELECT+?person+?name WHERE+ +?person+a+foaf:Person+; +++foaf:name+?name+. &output=htmltab







SPARCool.net

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

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http://sparcool.net

http://sparcool.net/j/dbp:abstract;l=en/http:/dbpedia.org/resource/Semantic_Web

http://sparcool.net/j/dbp:abstract;l=en/http:/dbpedia.org/resource/Semantic_Web


Setup a SPARQL endpoint

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

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http://arc.semsol.org/

http://helloopenworld.net/www2009/store1/index.phps


Loading RDF data

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

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http://helloopenworld.net/www09/store1/


Lightweight inference

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

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http://apassant.net/blog/2008/10/01/lightweight-subpropertyof-subclassof-inference-arc2












http://helloopenworld.net/www2009/store2/index.phps

http://helloopenworld.net/www2009/files/ARC2_SubPropertyInferenceTrigger.phps




Lightweight inference

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


SELECT ?person

WHERE

<YOUR_URI>foaf:knows ?person .

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http://helloopenworld.net/www2009/store2

http://helloopenworld.net/www2009/files/select2.sparql


Complex triggers

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

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http://helloopenworld.net/www2009/files/ARC2_InterestLoadTrigger.phps

http://helloopenworld.net/www2009/files/ARC2_InterestLoadTrigger.phps

http://helloopenworld.net/www2009/store3


SPARQL SELECT w/ Triggers

Advanced querying capabilities

http://helloopenworld.net/semtech2009/files/select3.sparql


PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT ?person

WHERE

?person foaf:topic_interest [

dbo:director<http://dbpedia.org/resource/Quentin_Tarantino

> . ]

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http://helloopenworld.net/www2009/files/q1.sparql


Outline

Content

Motivation





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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!

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Exhibit faceted browsing

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

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http://helloopenworld.net/www2009/files/construct2.sparql

http://helloopenworld.net/www2009/exhibit





Ubiquity command

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

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http://ubiquity.mozilla.com/

http://helloopenworld.net/www2009/ubiquity

http://en.wikipedia.org/wiki/Reservoir_Dogs


Ubiquity command

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Mash-up tools

DERI Pipes, a tool for semantic mashups

http://pipes.deri.org

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http://pipes.deri.org/


Sig.ma Mashup Maker

Web of data comes together

In an interactive mashup maker

Mashups can be embedded or queries programmatically

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Geolocation mash-ups

Since data is interlinked, it’s easy to combine it

Can mix personal and public data, e.g. in organisations

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Data directories

http://doapstore.org

A directory of Software projectsdescribedwith DOAP

CompletelyRDF-based

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http://doapstore.org


Ongoing works

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

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http://esw.w3.org/topic/PushBackDataToLegacySources

http://ld2sd.deri.org/pushback/

http://ld2sd.deri.org/pushback/

http://code.google.com/p/pushback/

http://rdfs.org/ns/rdforms

http://rdfs.org/ns/rdforms


Outline

Content

Motivation





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Conclusion

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)

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Events

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

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http://events.linkeddata.org/ldow2009/

http://www.semanticscripting.org/




Feedback

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

[email protected]

[email protected]

[email protected]

#swig on irc.freenode.net

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mailto:[email protected]




Hello Open World - Semtech 2009

Technology

Transcript of Hello Open World - Semtech 2009