London - New York - Dubai - Mumbai 2011

Dealing with the “new” data in the

“Cloud” – Linked Data

Table of Contents

Definitions 3

History 5

The Modigliani Test 11

Link Data 13

Raw Data 23

Resource Description Framework 30

Linked Data Principles 42

Publishing Linked Data 57

Faceted Browsers 65

On-the-fly Mashups 67

SPARQL 73

What is a Linked Data Application 77

Characteristics of a Linked Data Application 78

Contact Us 81

Definitions

RDF: The RDF data model is similar to classic conceptual

modelling approaches such as Entity-Relationship or Class

diagrams, as it is based upon the idea of making statements about

resources (in particular Web resources) in the form of subject-

predicate-object expressions. These expressions are known as

triples in RDF terminology. The subject denotes the resource, and

the predicate denotes traits or aspects of the resource and

expresses a relationship between the subject and the object. For

example, one way to represent the notion "The sky has the colour

blue" in RDF is as the triple: a subject denoting "the sky", a

predicate denoting "has the colour", and an object denoting "blue".

RDF is an abstract model with several serialization formats (i.e.,

file formats), and so the particular way in which a resource or

triple is encoded varies from format to format.

Definitions

SPARQL: (SPARQL Protocol and RDF Query Language,

pronounced "sparkle") is an RDF query language

Linked Data: Linked Data describes a method of publishing

structured data, so that it can be interlinked and become more

useful. It builds upon standard Web technologies, such as HTTP

and URIs - but rather than using them to serve web pages for

human readers, it extends them to share information in a way that

can be read automatically by computers. This enables data from

different sources to be connected and queried.

History

Linked Data Design Issues by Tim Berners-Lee July 2006

Linked Open Data Project WWW2007

First LOD Cloud May 2007

BBC publishes Linked Data 2008

NY Times announcement SemTech2009 - ISWC09

Data.gov.uk publishes Linked Data 2010

May 2007

Mar 2008

Sept 2008

Mar 2009

July 2009

The Modigliani Test

Show me all the locations of all the original paintings

of Modigliani

Daniel Koller (@dakoller) showed that you can find

this with a SPARQL query on DBpedia

So what is Linked Data?

Do you SEARCH or do you FIND?

Search for

Football Players who went to the University of

Texas at Austin, played for the Dallas Cowboys as

Cornerback

Why can’t we just FIND it…

Using the Current Web =internet + links + docs

is terribly inefficient

So what is the problem?

We aren’t always interested in documents

• We are interested in THINGS

• These THINGS might be in documents

We can read a HTML document rendered in a browser and find

what we are searching for

• This is hard for computers. It’s typically based on

guesswork from some primitive NLP engine, or simple

keyword search

What do we need to do?

Make it easy for computers/software to find THINGS

How can we do that?

• Besides publishing documents on the web

- which computers can’t understand easily

• Let’s publish something that computers can

understand

RAW DATA!

But don’t we already publish raw data in

RDBMS, XML, CSV, etc?

Yes!

But it’s not in a consistent format, and very

difficult to integrate (or “link”).

For example, how do I know that the

Wael Elrifai in Facebook is the same

as Wael Elrifai in Twitter

Don’t we already have a standard

way of publishing on the web?

We have a standardized way of

publishing documents on the web, right?

HTML

Then why can’t we have a standard way

of publishing data on the Web?

In fact, we do have one.

Resource Description Framework (RDF)

A data model

•A way to model data

•i.e. Relational databases use relational data model

RDF is a triple data model

Labeled Graph

Subject, Predicate, Object

<Wael> <was born in> <Beirut>

<Beirut> <is part of> <the Lebanon>

<Wael> <likes> <the Semantic Web>

RDF can be serialized in different ways

RDF/XML

RDFa (RDF in HTML)

N3

Turtle

JSON

So does that mean that I have to

publish my data in RDF now?

You don’t have to… but it sure

would be nice.

Document on the Web

Databases back up documents

Isbn Title Author PublisherID ReleasedData

978-0-596-15381-6

Programming the Semantic Web

Toby Segaran 1 July 2009

… … … … …

PublisherID PublisherName

1 O’Reilly Media

… …

This is a THING: A book title “Programming the Semantic Web” by Toby Segaran, …

THINGS have PROPERTIES: A Book as a Title, an author, …

Lets represent the data in RDF

Isbn Title Author PublisherID ReleasedData

978-0-596-15381-6

Programming the Semantic Web

Toby Segaran

1 July 2009

book

Programming the Semantic Web

978-0-596-15381-6

Toby Segaran

Publisher O’Reilly

title

name

author

publisher

isbn

PublisherID PublisherName

1 O’Reilly Media

Remember that we are on the web

Everything on the web is identified by a URL

And now let’s link the data to other data

http://…/isbn978

Programming the Semantic Web

978-0-596-15381-6

Toby Segaran

http://…/publisher1

O’Reilly

title

name

author

publisher

isbn

And now consider the data from Revyu.com

http://…/isbn978

http://…/revie

w1

Awesome Book

http://…/reviewer

Wael Elrifai

hasReview

reviewer

description

name

Let’s start to link data

http://…/isbn9

78

Programming the Semantic

Web

978-0-596-15381-6

Toby Segaran

http://…/publisher1 O’Reilly

title

name

author

publisher

isbn

http://…/isbn978

sameAs

http://…/revie

w1

Awesome Book

http://…/revie

wer

Wael Elrifai

hasReview

hasReviewer

description

name

Data on the Web that is in RDF and

is linked to other RDF data is

LINKED DATA

Linked Data Principles

1. Use URIs as names for things

2. Use HTTP URIs so that people can look up

(dereference) those names.

3. When someone looks up a URI, provide

useful information.

4. Include links to other URIs so that they can

discover more things.

Linked Data makes the web appear

a single global database!

The same can be done inside your company!

What if you wanted to know your company’s

EBITDA for Catalonia in 2010?

You could have a EDW pre-aggregate and

distribute the data, an analyst calculate it on

the spot, or…

Linked data in your internal semantic

web could relate all transactions to a

linked financial formulae!

You ask the question, tell your system

where to look (as part of the question,

this can be prebuilt) and voilà!

I can query a database with SQL. Is

there a way to query Linked Data with a

query language?

Yes! There is actually a standardize

language for that

FIND all the reviews on the book

“Programming the Semantic Web”

by people who live in London

http://…/isbn9

78

Programming the Semantic

Web

978-0-596-15381-6

Toby Segaran

http://…/publishe

r1

O’Reilly

title

name

author

publisher

isbn

http://…/isbn978

sameAs

http://…/review1

Awesome Book

http://…/reviewer

Wael Elrifai

http://waelworldwide.com

hasReview

hasReviewer

description

name

sameAs

livesIn

Wael Elrifai name

http://dbpedia.org/London

This looks cool, but let’s be realistic.

What is the incentive to publish

Linked Data?

What was your incentive to publish

an HTML (Intranet) page in 1990?

1) Share data in documents

2) Because you neighbor was doing it

So why should we publish

Linked Data in 2011?

1) Share data as data

2) Because you neighbor is doing it

You’ll be among good company…

Linked Data Publishers

UK Government

US Government

BBC

Open Calais – Thomson Reuters

Freebase

NY Times

Best Buy

CNET

Dbpedia

How can I publish Linked Data?

Publishing Linked Data

• Legacy Data in Relational Databases

• D2R Server

• Virtuoso

• Triplify

• Ultrawrap

• CMS

• Drupal 7

• Native RDF Stores

• Databases for RDF (Triple Stores)

• AllegroGraph, Jena, Sesame, Virtuoso

• Talis Platform (Linked Data in the Cloud)

• In HTML with RDFa

Consuming Linked Data by Humans

HTML Browsers

RDF can be serialized in RDFa

Have you heard of

•Yahoo’s Search Monkey

•Google Rich Snippets?

They are consuming RDFa

But WHY?

Because there is life beyond ten

blue links

Google and Yahoo are starting to crawl

RDFa!

The Semantic Web is a reality!

The Reality

• Yahoo is crawling data that is in RDFa and

Microformats under a specific vocabularies

• FOAF

• GoodRelations

• Google is crawling RDFa and Microformaats that

use the Google vocabulary

Linked Data Browsers

Tabulator

•http://www.w3.org/2005/ajar/tab

OpenLink

•http://ode.openlinksw.com/

Zitgist Dataviewr

•http://dataviewer.zitgist.com/

Marbles

•http://www5.wiwiss.fu-berlin.de/marbles/

Explorator

•http://www.tecweb.inf.puc-rio.br/explorator

Faceted Browsers

http://dbpedia.neofonie.de

http://dev.semsol.com/2010/semtech/

On-the-fly Mashups

http://sig.ma

What’s next?

Time to create new and innovative

ways to interact with Linked Data

This may be one of the Killer Apps that we have all been

waiting for

http://en.wikipedia.org/wiki/File:Mosaic_browser_plaque_ncsa.jpg

Where can I find SPARQL Endpoints?

Dbpedia:

http://dbpedia.org/sparql

Musicbrainz: http://dbtune.org/musicbrainz/sparql

U.S. Census:

http://www.rdfabout.com/sparql

Semantic Crunchbase: http://cb.semsol.org/sparql

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

• Querying a single dataset is quite boring

compared to:

• Issuing SPARQL queries over multiple datasets

• How can you do this?

1. Issue follow-up queries to different endpoints

2. Querying a central collection of datasets

3. Build store with copies of relevant datasets

4. Use query federation system

Follow-up Queries

• Idea: issue follow-up queries over other

datasets based on results from previous

queries

• Substituting placeholders in query templates

Getting Started

• Finding URIs

• Finding Additional Data

• Finding SPARQL Endpoints

What is a Linked Data application

Software system that makes use of data on the

web from multiple datasets AND that benefits

from links between the datasets

Characteristics of Linked Data Applications

• Consume data that is published on the web following

the Linked Data principles

• Discover further information by following the links

between different data sources

• Combine the consumed linked data with data from

sources (not necessarily Linked Data)

• Expose the combined data back to the web

following the Linked Data principles

• Offer value to end-users

Examples

• http://data-gov.tw.rpi.edu/wiki

• http://dbrec.net/

• http://fanhu.bz/

• http://data.nytimes.com/schools/schools.html

• http://sig.ma

• http://visinav.deri.org/semtech2010/

Hot Research Topics

• Interlinking Algorithms

• Provenance and Trust

• Dataset Dynamics

• UI

• Distributed Query

Contact

PEAK Consulting

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