Introduction to Linked DataConsuming Linked Data TutorialInternational Semantic Web Conference 2009

Do you SEARCH or do you FIND?

Search forFootball 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?

I’ll tell you how I did NOT find it

Current Web = internet + links + docs

So what is the problem?The Web has problemsPeople aren’t interested in documentsThey are interested in things People can parse documents and extract meaningWeb pages are written in HTMLHTML describes visualization of informationComputers can’t!

What do we need to do?We need to help machines to understand the web so machines can help us understand thingsThey can learn what we are interested inThey can help us better find what we want

How can we do that?Besides publishing documents on the webwhich computers can’t understand easilyLet’s publish something that computers can understand

RAW DATA!

But wait… don’t we do that already?

Current Data on the WebRelational DatabasesAPIsXMLCSVXLS…Can’t computers and applications already consume that data on the web?

True! 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

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!

Resource Description Framework (RDF)A data model A way to model datai.e. Relational databases use relational data modelRDF is a triple data modelLabeled GraphSubject, Predicate, Object<Juan> <was born in> <California><California> <is part of> <the USA><Juan> <likes> <the Semantic Web>

RDF can be serialized in different waysRDF/XMLRDFa (RDF in HTML)N3Turtle

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 documentsTHINGS 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 RDFProgramming the Semantic WebtitleauthorbookToby Segaranisbn978-0-596-15381-6publishernamePublisherO’Reilly

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

And now let’s link the data to other dataProgramming the Semantic Webtitleauthorhttp://…/isbn978Toby Segaranisbn978-0-596-15381-6publishernamehttp://…/publisher1O’Reilly

And now consider the data from Revyu.comhasReviewhttp://…/review1http://…/isbn978descriptionreviewerAwesome Bookhttp://…/reviewernameJuan Sequeda

Let’s start to link datahasReviewhttp://…/review1http://…/isbn978Programming the Semantic WebtitledescriptionsameAshasReviewerAwesome Bookauthorhttp://…/isbn978Toby Segaranhttp://…/reviewernameisbn978-0-596-15381-6Juan Sequedapublishernamehttp://…/publisher1O’Reilly

Juan Sequeda publishes data toohttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

Let’s link more datahasReviewhttp://…/review1http://…/isbn978descriptionhasReviewerAwesome Bookhttp://…/reviewernameJuan SequedasameAshttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

And morehasReviewhttp://…/review1http://…/isbn978Programming the Semantic WebtitledescriptionsameAshasReviewerAwesome Bookauthorhttp://…/isbn978Toby Segaranhttp://…/reviewernameisbn978-0-596-15381-6Juan SequedapublishersameAshttp://…/publisher1nameO’Reillyhttp://juansequeda.com/idhttp://dbpedia.org/AustinlivesInnameJuan Sequeda

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

Linked Data PrinciplesUse URIs as names for thingsUse 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 thatSPARQL

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

hasReviewhttp://…/review1http://…/isbn978Programming the Semantic WebtitledescriptionsameAshasReviewerAwesome Bookauthorhttp://…/isbn978Toby Segaranhttp://…/reviewernameisbn978-0-596-15381-6Juan SequedapublishersameAsnamehttp://…/publisher1O’Reillyhttp://juansequeda.comhttp://dbpedia.org/AustinlivesInnameJuan 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

So why should we publish Linked Data in 2009?

1) Share data as data2) Because you neighbor is doing it

And guess who is starting to publish Linked Data now?

Linked Data Publishers 2009UK GovernmentUS GovernmentBBCOpen Calais – Thomson ReutersFreebaseNY TimesBest BuyCNETDbpediaAre you?

How can I publish Linked Data?

Publishing Linked DataLegacy Data in Relational DatabasesD2R ServerVirtuosoTriplifyUltrawrapCMSDrupalNative RDF StoresDatabases for RDF (Triple Stores)AllegroGraph, Jena, Sesame, VirtuosoTalis Platform (Linked Data in the Cloud)In HTML with RDFa

Questions?