Introduc)on to Linked Data Consuming Linked Data Tutorial World Wide Web Conference 2010
Jan 25, 2015
Introduc)on to Linked Data
Consuming Linked Data Tutorial World Wide Web Conference 2010
Do you SEARCH or do you FIND?
Search for
Football Players who went to the University of Texas at Aus)n, 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 problems – People aren’t interested in documents • They are interested in things (that are in documents)
– People can parse documents and extract meaning • Web pages are wriXen in HTML • HTML describes visualiza)on of informa)on
• Computers can’t!
What do we need to do?
• We need to help machines to understand the web so machines can help us understand things – They can learn what we are interested in – They can help us beXer find what we want
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 wait… don’t we do that already?
Current Data on the Web
• Rela)onal Databases • APIs • XML • CSV • XLS • … • Can’t computers and applica)ons 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 TwiXer
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 ques)on! And the answer is YES. There is!
Resource Descrip)on Framework (RDF)
• A data model – A way to model data – i.e. Rela)onal databases use rela)onal 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> <likes> <the Seman)c 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 we would like you to
An example
Document on the Web
Databases back up documents
Isbn Title Author PublisherID ReleasedData
978-‐0-‐596-‐15381-‐6
Programming the Seman.c Web
Toby Segaran 1 July 209
… … … … …
PublisherID PublisherName
1 O’Reilly Media
… …
This is a THING: A book )tle “Programming the Seman)c Web” by Toby Segaran, …
THINGS have PROPERTIES: A Book as a Title, an author, …
Lets represent the data in RDF
book
Programming the Seman)c Web
978-‐0-‐596-‐15381-‐6
Toby Segaran
Publisher O’Reilly
)tle
name
author
publisher
isbn
Remember that we are on the web
Everything on the web is iden)fied by a URI
And now let’s link the data to other data
hXp://…/isbn978
Programming the Seman)c Web
978-‐0-‐596-‐15381-‐6
Toby Segaran
hXp://…/publisher1 O’Reilly
)tle
name
author
publisher
isbn
And now consider the data from Revyu.com
hXp://…/isbn978
hXp://…/review1
Awesome Book
hXp://…/reviewer
Juan Sequeda
hasReview
reviewer
descrip)on
name
Let’s start to link data
hXp://…/isbn978
Programming the Seman)c Web
978-‐0-‐596-‐15381-‐6
Toby Segaran
hXp://…/publisher1 O’Reilly
)tle
name
author
publisher
isbn
hXp://…/isbn978
sameAs
hXp://…/review1
Awesome Book
hXp://…/reviewer
Juan Sequeda
hasReview
hasReviewer
descrip)on
name
Juan Sequeda publishes data too
hXp://juansequeda.
com/id
livesIn
Juan Sequeda name
hXp://dbpedia.org/Aus)n
Let’s link more data hXp://…/isbn978
hXp://…/review1
Awesome Book
hXp://…/reviewer
Juan Sequeda
hXp://juansequeda.
com/id
hasReview
hasReviewer
descrip)on
name
sameAs
livesIn
Juan Sequeda name
hXp://dbpedia.org/Aus)n
And more
hXp://…/isbn978
Programming the Seman)c Web
978-‐0-‐596-‐15381-‐6
Toby Segaran
hXp://…/publisher1
O’Reilly
)tle
name
author
publisher
isbn
hXp://…/isbn978
sameAs
hXp://…/review1
Awesome Book
hXp://…/reviewer
Juan Sequeda
hXp://juansequeda.
com/id
hasReview
hasReviewer
descrip)on
name
sameAs
livesIn
Juan Sequeda name
hXp://dbpedia.org/Aus)n
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 informa)on.
4. Include links to other URIs so that they can discover more things.
Linked Data makes the web appear as ONE GIANT HUGE
GLOBAL DATABASE!
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 Seman)c Web”
by people who live in Aus)n
hXp://…/isbn978
Programming the Seman)c Web
978-‐0-‐596-‐15381-‐6
Toby Segaran
hXp://…/publisher1 O’Reilly
)tle
name
author
publisher
isbn
hXp://…/isbn978
sameAs
hXp://…/review1
Awesome Book
hXp://…/reviewer
Juan Sequeda
hXp://juansequeda.
com
hasReview
hasReviewer
descrip)on
name
sameAs
livesIn
Juan Sequeda name
hXp://dbpedia.org/Aus)n
This looks cool, but let’s be realis)c. What is the incen)ve to publish
Linked Data?
What was your incen)ve to publish an HTML page in 1990?
1) Share data in documents 2) Because you neighbor was doing it
So why should we publish Linked Data in 2010?
1) Share data as data 2) Because you neighbor is doing it
And guess who is star)ng to publish Linked Data now?
Linked Data Publishers
• UK Government • US Government • BBC • Open Calais – Thomson Reuters • Freebase • NY Times • Best Buy • CNET • Dbpedia • Are you?
How can I publish Linked Data?
Publishing Linked Data • Legacy Data in Rela)onal Databases – D2R Server – Virtuoso – Triplify – Ultrawrap
• CMS – Drupal 7
• Na)ve RDF Stores – Databases for RDF (Triple Stores)
• AllegroGraph, Jena, Sesame, Virtuoso – Talis Plauorm (Linked Data in the Cloud)
• In HTML with RDFa
Ques)ons?