Linking Open Data

Linking the world of data

Iftikhar Alam

What is now

User generated content is growing tremendously Post Ajax era…Blogs, wiki, comments, tags,

Isolated contents need deadly to get connected. An idea of Tim Berners-Lee (Semantic Web)

The world is connected, so do the data, information and knowledge should be connected.

Old termsData

Structured formatClosed environment (Database: As a set)Slow growth (in context of Database)Display of results in any order is not an issue

Select * from students;Information

Un-structured formatOpen environment (for every one), No

restriction on its contentsOrder of result is important issue

Old terms…. Knowledge – contextualizing information

Comprehend the perceived informationAdd context (hp, core i7, ITB, 8GB RAM)…

Context ultimately determines what’s actually what.

Contextualization aids comprehension. For example, an arithmetic problem may not seem very practical until it is seen within a story problem; the real-life situation contextualizes the math problem and makes it more understandable.

 Pythagoras's theorema2+b2=c2

DBPedia..

Extract structured data from WikipediaExample Wasim Akram

Date of birth, name, matches etc.Database to RDF

Apply SPARQL statements ..1.PREFIX plant:   <http://www.linkeddatatools.com/plants>2.FROM <http://www.linkeddatatools.com/plantsdata/plants.rdf>3.SELECT ?name WHERE {4.?planttype plant:planttype ?name.5.}6.ORDER BY ?name

What is in our daily life

Access dataManipulate data (add, delete, change)Process data

Generate information (tables, forms)Create knowledge (reports, papers..)

Data is our life

Data is our daily breadDo we have identifier for data?

Not really important if data is small and individual (your class we don’t needs roll numbers)

Really important if data is huge and connected

? Should we need identifier for our data? Why do we need our name, or NIC number

? Can you refer to someone without identifier?a person with good heart----

Make our busy life less messy

We just got 24 hours per day, not moreAdd identifier to our data

Give the everyone-agreed-unique-identifier to each data -- the perfect world of our dreamland We will not have any integration problem, most of the IT

departments can be closed

Different groups give different identifiers to the same data – we can live with that, it is more real in our daily life, standardization bodies and IT guys are helping us (NIC is required for SIM Registration, but not as roll number or registration number).

We are happy that we can refer to data

Where are our data

In computerOn the Web

In my paper notesIn printed books…

Data are being digitalized and are available onlineWeb Data

Web data

Data on the Web Online journal Blog Wiki …

Data in physical world Yourself Table Book in library Computer you are using …

The boundary is blurring Paper is both in your hand and on the Web

How to refer data

Web data DOI (Digital Object Identifier)

Alphnumeric strings, APA style starts with 10

OpenID (Logging into other websites using facebook)

URI (blog, wiki, homepage, …) …

URI (Uniform Resource Identifier)

To identify or name a resource on the InternetThe main purpose is to enable interaction with

representations of the resource over a network, typically WWW, using specific protocols

URN – like a person’s name

urn:isbn:0-486-27557-4 – Book of “Romeo and Juliet”URL – like a street address

http://www.slis.indiana.edu

Linked Data

A term coined by Tim Berners-LeeIt describes HTTP-based Data Access by

Reference for the WebCurrent web is changing from hypertext links

(link documents) to hyperdata links (linking data)Data are small components of the resources It drills deep to the details of the resources

Linked data provides a powerful mechanism for meshing disparate and heterogeneous data

Vision from Sir Berners-Lee

“The Semantic Web isn’t just about putting data on the web. It is about making links”.

Four Rules for linking data Use URIs as names for things Use HTTP URIs so that people can look up those names When someone looks up a URI, provide useful information

(URI dereferencing) Include links to other URIs, so that they can discover more

things “Breaking them does not destroy anything, but misses an

opportunity to make data interconnected. This in turn limits the ways it can later be reused in unexpected ways. It is the unexpected re-use of information which is the value added by the web”

W3C SWEO Linking Open Data Project

Project aims to "The goal of the W3C SWEO Linking Open Data community project is to extend the

Web with a data commons by publishing various open datasets as RDF on the Web and by setting RDF links between data items from different data sources."

Publish existing open license datasets as linked data on the web

Interlink things between different data sourcesDevelop clients and applications that consume

linked data from the web

Bubbles in May 2007

Over 500M RDF triples

Around 120K RDF links between data sources

Bubbles in April 2008

>2B RDF triples

Around 3M RDF links

Bubble now

Semantic search engines

Use RDF Sindice Falcons (temporarily not available)

More on w3c website

Organization participating in the LOD community

AcademicMIT, Univ Southampton, DERI, Open Univ,

Univ London, Univ Hannover, Penn State Univ, Univ Leipzig, Univ Karlsruhe, Joanneum (AT), Free Univ Berlin, Cyc, SouthEast Univ (CN), …

CommercialBBC, OpenLink, Talis, Zitgist, Garlik, Mondeca,

Renault, Boad Interactive

What are Linked Data?

Linked Data require RDF

But not all RDF data are linked dataYou have to compliant your RDF data

according to the four rules mentioned by Berners-Lee

What is RDF?

Basic Ideas behind RDF

RDF uses Web identifiers (URIs) to identify resources

RDF describes resources with properties and property valuesEverything can be represented as triples

The essence of RDF is the (s,p,o) triple

Resource(subject)

Value(object)

Property

(predicate)

Subject has a property with value “object ” (s,p,o)

RDF Triples

Triple A Resource (Subject) is anything that can have a URI: URIs

or blank nodes A Property (Predicate) is one of the features of the Resource:

URIs A Property value (Object) is the value of a Property, which

can be literal or another resource: URIs, literal, blank nodes

Resource(subject)

Value(object)

Property

(predicate)

Literals can be the object of an RDF statement, but cannot be the subject or the predicate

Do you have linked data

Linked data are just RDF triples

How can I get RDF triplesRelational database:

D2R tools can convert them for youRDFizers from SIMILE:

Can convert JPEG, MARC/MODS, OAI-PMH, OCW(MIT Open Course), Email, BibTex, Java, Javadoc, etc. to RDF

<rdf:Description about=“http://example.org/smith#albert”> <fam:hasChild rdf:Resource="http://example.org/smith#brian">  <fam:hasChild rdf:Resource="http://example.org/smith#carol"></rdf:Description>

Thumb of the rules

Understand your dataWhat do you want to have in your dataDo not reinvent – REUSE!

Potential ontologies/vocabularies• FOAF, SIOC, Geo

URI AliasesDifferent URIs for the same non-information

resource (Berlin, etc.)owl:sameAs to link these URI aliases

More principles

Linked Data is simply about using the Web to create typed links between data from different sources.

The principle of Linked data is to:Use the RDF data model to publish structured

data on the webUse RDF links to interlink data from different

data sources.Use HTTP URIs to identify resource

To avoid other URI schemes (URNs or DOIs)

Power of Linked Data

ying foaf:Person

rdf:type

Ying Ding

foaf:name

Stefanfoaf:knows

db:Galway

72K

dp:population

dp:Cities_in_Ireland

skos:subjectdp:Dublin

foaf:based_near

skos:subject

dblp:publications

foaf:publication

What LOD can bring?

It will lift current document web up to a data webLOD browsers can let you navigate between

different data sources by following RDF links.It can drill down to the lower granularity of the

informationallowing you for more fine search on the webmaking the question-answer search on the Web

possiblemeshing up different data through RDF linksMaking the built-on-top application easier

Document Web vs. Data Web

Document Web Glued by hyperlinks Data are HTML pages Query result is HTML

pages, which can not be further processed

Data are just interlinked, but not integrated

Data access through different APIs

Data Web Glued by RDF links Data are RDF triples Query result is RDF

triples which can be easily further processed (e.g., web services)

Data are interlinked and integrated, and links are typed

Data access through a single and standardized access mechanism (maybe it will called in the future LOD API?)

More about LOD

LOD Wiki http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/

LinkingOpenData Tutorial on how to publish LOD data

http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/Further readings and tools

W3C Track LOD WWW2008 http://www.w3.org/2008/Talks/WWW2008-W3CTrack-LOD.pdf

Linked Data Planet in New York 2008 http://linkeddata.org/slides/2008-06-nyc-ldp.pdf

LDOW2008 workshop in WWW2008 http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-

369/ ISWC 2008 LOD tutorial

http://events.linkeddata.org/iswc2008tutorial LOD mailinglist