Introduction to Linked Data 1/5

Introduction to Linked Data
Juan F. Sequeda
Semantic Technology Conference
June 2011

What is the Semantic Web?

Internet != Web

What is the Web?
“… the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images […] and navigate between them via hyperlinks”
http://en.wikipedia.org/wiki/World_Wide_Web

Current Web = internet + links + docs

History of the Web
Created by Tim Berners-Lee at CERN in 1989
Mosaic browser in 1993
W3C created in 1994
Exponential growth mid 90s
Amazon, Ebay – 1995
Search engines – Google 1998
Dot-com boom 1997 – 2001
Web 2.0 – blogs, Facebook, Twitter, etc

What is the problem?

WHAT’S THE WEATHER IN SAN FRANCISCO TODAY?

What is the problem?
The web is full of documents
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.
Computers have to guess (even though they are pretty good at it)

The Web is a Data Shredder
Structured Data
Unstructured Data
Thanks Martin Hepp

What would we like?
Make it easy for computers/software to find THINGS
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…

Guess how I FOUND out?

On a Semantic Web
Besides publishing documents on the web
which computers can’t understand easily
Let’s publish on the web something that computers can understand
DATA

The Semantic Web is a web of linked data
The current web is a web of
linked documents

But wait… doesn’t the web already have data?

Current Data on the Web
Relational Databases
APIs
XML
CSV
XLS
…
Can’t computers and applications already consume that data on the web?

Yes! But it is all in different formats and data models!

This makes it hard to integrate data

The data in different data sources aren’t linked

For example, how do I know that the Juan Sequeda in Facebook is the same as Juan Sequeda in Twitter

Or if I create a mashup from different services, I have to learn different APIs and I get different formats of data back

Data is Siloed

Wouldn’t it be great if we had a standard way of publishing data 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?

Good question! And the answer is YES. There is!
RDF

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
<Juan> <was born in> <California>
<California> <is part of> <the USA>
<Juan> <has hobby> <Salsa dancing>

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 we would like you to 

An example

Document on the Web

Databases back up documents
THINGS have PROPERTIES:
A Book as a Title, an author, …
This is a THING:
A book title “Programming the Semantic Web” by Toby Segaran, …

Lets represent the data in RDF
Programming the Semantic Web
title
author
book
Toby Segaran
isbn
978-0-596-15381-6
publisher
name
Publisher
O’Reilly

Remember that we are on the web
Everything on the web is identified by a URI

And now let’s link the data to other data
title
author
http://…/isbn978
Toby Segaran
isbn
978-0-596-15381-6
publisher
name
http://…/publisher1
O’Reilly

And now consider the data from Revyu.com
hasReview
http://…/review1
http://…/isbn978
description
reviewer
Awesome Book
http://…/reviewer
name
Juan Sequeda

Let’s start to link data
hasReview
http://…/review1
http://…/isbn978
title
description
sameAs
hasReviewer
Awesome Book
author
http://…/isbn978
Toby Segaran
http://…/reviewer
name
isbn
978-0-596-15381-6
Juan Sequeda
publisher
name
O’Reilly

Juan Sequeda publishes data too
http://juansequeda.com/id
http://dbpedia.org/Austin
livesIn
name
Juan Sequeda

Let’s link more data
hasReview
http://…/review1
http://…/isbn978
description
hasReviewer
Awesome Book
http://…/reviewer
name
Juan Sequeda
sameAs
livesIn
name
Juan Sequeda

And more
hasReview
http://…/review1
http://…/isbn978
title
description
sameAs
hasReviewer
Awesome Book
author
http://…/isbn978
Toby Segaran
http://…/reviewer
name
isbn
978-0-596-15381-6
Juan Sequeda
publisher
sameAs
name
O’Reilly
livesIn
name
Juan Sequeda

Data on the Web that is in RDF and is linked to other RDF data is LINKED DATA

Linked Data Principles
Use URIs as names for things
Use HTTP URIs so that people can look up (dereference) those names.
When someone looks up a URI, provide useful information.
Include links to other URIs so that they can discover more things.

Linked Data makes the web appear as ONEGIANTHUGEGLOBALDATABASE!

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
SPARQL

FIND all the reviews on the book “Programming the Semantic Web” by people who live in Austin

SELECT ?review ?comment
WHERE {
isbn:978 ex:hasReview ?review .
?review ex:description ?comment .
?review ex:hasReviewer ?person .
?person ex:livesdbpedia:Austin .
}

SELECT ?review ?comment
WHERE {
isbn:978 ex:hasReview ?review .
?review ex:description ?comment .
?review ex:hasReviewer ?person .
?person ex:livesdbpedia:Austin .
}
hasReview
http://…/review1
http://…/isbn978
title
description
sameAs
hasReviewer
Awesome Book
author
http://…/isbn978
Toby Segaran
http://…/reviewer
name
isbn
978-0-596-15381-6
Juan Sequeda
publisher
sameAs
name
O’Reilly
http://juansequeda.com
livesIn
name
Juan Sequeda

This looks cool, but let’s be realistic. What is the incentive to publish Linked Data?

What was your incentive to publish an HTML page in 1990?

1) Share data in documents2) Because you neighbor was doing it… later on …3) Marketing, Advertising, SEO

So why should we publish Linked Data in 2011?

1) Share data as data2) Because you neighbor is doing it…3) (Semantic) SEO ++

Linked Data Publishers
UK Government
US Government
BBC
Open Calais – Thomson Reuters
Freebase/Google
NY Times
Best Buy
CNET
Dbpedia
Overstock.com
O’Reilly Media
…

May 2007

Oct 2007

Nov 2007

Feb 2008

Mar 2008

Sept 2008

Mar 2009 (1)

Mar 2009 (2)

July 2009

September 2010

June 2011
YOU GET THE PICTURE
ITS BIG and getting BIGGER and
BIGGER

QUESTIONS?

Introduction to Linked Data 1/5

by Juan Sequeda on Jun 06, 2011

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Introduction to Linked Data 1/5 — Presentation Transcript