linking open data linking the world of data iftikhar alam
TRANSCRIPT
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