Introduction to Linked Data 1/5

Introduction to Linked DataJuan F. SequedaSemantic Technology ConferenceJune 2011

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

WHAT’S THE WEATHER IN SAN FRANCISCO TODAY?

What is the problem?The web is full of documentsWe aren’t always interested in documentsWe are interested in THINGSThese THINGS might be in documentsWe can read a HTML document rendered in a browser and find what we are searching forThis is hard for computers. Computers have to guess (even though they are pretty good at it)

The Web is a Data ShredderStructured DataUnstructured DataThanks Martin Hepp

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

On a Semantic WebBesides publishing documents on the webwhich computers can’t understand easilyLet’s publish on the web something that computers can understandDATA

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

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

Current Data on the WebRelational DatabasesAPIsXMLCSVXLS…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

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 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> <has hobby> <Salsa dancing>

RDF can be serialized in different waysRDF/XMLRDFa (RDF in HTML)N3TurtleJSON

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 

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 and is linked 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

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

SELECT ?review ?commentWHERE {isbn:978 ex:hasReview ?review .?review ex:description ?comment .?review ex:hasReviewer ?person .?person ex:livesdbpedia: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… 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 PublishersUK GovernmentUS GovernmentBBCOpen Calais – Thomson ReutersFreebase/GoogleNY TimesBest BuyCNETDbpediaOverstock.comO’Reilly Media…

June 2011YOU GET THE PICTUREITS BIG and getting BIGGER andBIGGER

Introduction to Linked Data 1/5

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Introduction to Linked Data 1/5