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 terms Data  Structured format  Closed 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 format  Open environment (for every one), No restriction on its contents  Order of result is important issue

Old terms…. Knowledge – contextualizing information  Comprehend the perceived information Add 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 theorem a 2 +b 2 =c 2

DBPedia.. Extract structured data from Wikipedia  Example Wasim Akram Date of birth, name, matches etc. Database to RDF Apply SPARQL statements.. 1.PREFIX plant: 2.FROM 3.SELECT ?name WHERE { 4.?planttype plant:planttype ?name. 5.} 6.ORDER BY ?name

What is in our daily life Access data Manipulate data (add, delete, change) Process data  Generate information (tables, forms)  Create knowledge (reports, papers..)

Data is our life Data is our daily bread Do 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 more Add 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 computer On the Web In my paper notes In printed books … Data are being digitalized and are available online  Web 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 Internet The 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: – Book of “Romeo and Juliet”  URL – like a street address

Linked Data A term coined by Tim Berners-Lee It describes HTTP-based Data Access by Reference for the Web Current 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 sources  Develop 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 Academic  MIT, 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), … Commercial  BBC, OpenLink, Talis, Zitgist, Garlik, Mondeca, Renault, Boad Interactive

What are Linked Data? Linked Data require RDF But not all RDF data are linked data  You 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 values  Everything 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 triples  Relational database: D2R tools can convert them for you  RDFizers from SIMILE: Can convert JPEG, MARC/MODS, OAI-PMH, OCW(MIT Open Course), , BibTex, Java, Javadoc, etc. to RDF

Thumb of the rules Understand your data  What do you want to have in your data  Do not reinvent – REUSE! Potential ontologies/vocabularies FOAF, SIOC, Geo  URI Aliases Different 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 web  Use 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 Stefan foaf:knows db:Galway 72K dp:population dp:Cities_in_Ireland skos:subject dp:Dublin foaf:based_near skos:subject dblp:publications foaf:publication

What LOD can bring? It will lift current document web up to a data web LOD browsers can let you navigate between different data sources by following RDF links. It can drill down to the lower granularity of the information  allowing you for more fine search on the web  making the question-answer search on the Web possible  meshing up different data through RDF links  Making 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  OpenData OpenData Tutorial on how to publish LOD data  Further readings and tools W3C Track LOD WWW2008  Linked Data Planet in New York 2008  LDOW2008 workshop in WWW2008  369/ 369/ ISWC 2008 LOD tutorial  LOD mailinglist