linked data technology & status
DESCRIPTION
Linked Data Technology & Status. Dr. Myungjin Lee. The Semantic Web. more vocabulary for describing properties and classes. a vocabulary for describing properties and classes of RDF-based resources. to exchange rules between many "rules languages ". - PowerPoint PPT PresentationTRANSCRIPT
Linked Data & Semantic Web Technology
Linked DataTechnology & Status
Dr. Myungjin Lee
Linked Data & Semantic Web Technology
The Semantic Web
an elemental syntaxfor content structurewithin documents
a simple languagefor expressing data models,
which refer to objects ("resources")and their relationships
more vocabularyfor describing properties and classes
a vocabulary for describingproperties and classes
of RDF-based resources
a protocol and query languagefor semantic web data sources
to exchange rulesbetween many "rules languages"
a string of characters used to identify a name or a resource
Linked Data & Semantic Web Technology http://www.w3.org/2007/Talks/0130-sb-W3CTechSemWeb/#(24)
Linked Data & Semantic Web Technology
What is Linked Data?Linked data describes a method of publishing structured data so that it can be interlinked and become more useful.
The Semantic Web isn't just about putting data on the web. It is about making links, so that a person or machine can explore the web of data. With linked data, when you have some of it, you can find other, related, data.
- A roadmap to the Semantic Web by Tim Berners-Lee
http://www.w3.org/DesignIssues/LinkedData.html
Linked Data & Semantic Web Technology
Four Principles of Linked Data 1. Use URIs to identify things.
2. Use HTTP URIs so that these things can be referred to and looked up ("dereferenced") by people and user agents.
3. Provide useful information about the thing when its URI is dereferenced, using standard formats such as RDF/XML.
4. Include links to other, related URIs in the exposed data to improve discovery of other related informa-tion on the Web.
http://www.w3.org/DesignIssues/LinkedData.html
Linked Data & Semantic Web Technology
5 Star Linked Data★ Available on the web (whatever format) but with an
open licence, to be Open Data
★★ Available as machine-readable structured data (e.g. excel instead of image scan of a table)
★★★ as (2) plus non-proprietary format (e.g. CSV instead of excel)
★★★★ All the above plus, Use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff
★★★★★ All the above, plus: Link your data to other people’s data to provide context
http://www.w3.org/DesignIssues/LinkedData.html
Linked Data & Semantic Web Technology
The Basic Requirements for Linked Data
an elemental syntaxfor content structurewithin documents
a simple languagefor expressing data models,
which refer to objects ("resources")and their relationships
a vocabulary for describingproperties and classes
of RDF-based resources
a protocol and query languagefor semantic web data sources
a string of characters used to identify a name or a resource
Linked Data & Semantic Web Technology
Linked Data & Semantic Web Technology http://www.google.co.kr/search?q=namdeamun
Linked Data & Semantic Web Technology
URI, Thing, and Representation
Thing
URI
Representation
http://data.kdata.kr/resource/Namdaemun
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Namdaemun | kdata.kr</title> <link rel="alternate" type="application/rdf+xml" href="http://data.kdata.kr/data/Namdaemun" title="RDF" /></head> <body onLoad="init();"> <div id="header"> <div> <h1 id="title">Namdaemun</h1> <div id="homelink"> at <a href="http://kdata.kr">kdata.kr</a>
identifiesand
names
represents
looks up
URIhttp://dbpedia.org/resource/Namdaemun
URIhttp://data.kdata.kr/resource/Sungnyemun
links
refers
PersonMachine
http://www.slideshare.net/lysander07/open-hpi-semweb02part1
Linked Data & Semantic Web Technology http://www.w3.org/TR/cooluris/
Linked Data & Semantic Web Technology
URIs for Real-World Objects• Be on the Web
– Given only a URI, machines and people should be able to retrieve a description about the resource identified by the URI from the Web.
• Be unambiguous– There should be no confusion between identifiers for
Web documents and identifiers for other resources.
http://www.w3.org/TR/cooluris/
Linked Data & Semantic Web Technology
URIs for Real-World Objects
<URI-of-alice> a foaf:Person; foaf:name "Alice"; foaf:mbox <mailto:[email protected]>; foaf:homepage <http://www.example.com/people/alice> .
ID
RDF HTML
Resource identifier (URI)
RDF document URI HTML document URI
for web browsersfor semantic web applications
http://www.w3.org/TR/cooluris/
Linked Data & Semantic Web Technology
Distinguishing between Representations and De-scriptions
GenericDocument
RDF HTML
http://data.kdata.kr/page/Namdaemun
http://data.kdata.kr/page/Namdaemun.rdf http://data.kdata.kr/page/Namdaemun.html
text/htmlapplication/rdf+xml
Thing
http://data.kdata.kr/resource/Namdaemun
303 redirect
contentnegotiation
Linked Data & Semantic Web Technology
Cool URIs• Simplicity
– short and mnemonic
• Stability– remain as long as possible
• Manageability– issue your URIs in a way that you can manage
http://www.w3.org/TR/cooluris/
Linked Data & Semantic Web Technology
Designing URI Sets for the UK Public Sector• URIs:
– name the set and describe its characteristics– identify for the real-world ‘Things’ in a single con-
cept– provide a means of looking up data on the web– provide mechanisms to:
• lookup an Identifier URI and be redirected to its Document URI
• discover and get each of the Representation URIs
URI Type URI structure Examples
Identifier http://{domain}/id/{concept}/{reference} http://education.data.gov.uk/id/school/78
https://www.gov.uk/government/publications/designing-uri-sets-for-the-uk-public-sectorhttp://data.gov.uk/resources/uris
Linked Data & Semantic Web Technology
URI Design Principles:Creating Unique URIs for Government Linked Data
• URI Template:
'http://' BASE '/' 'id' '/' ORG '/' CATEGORY ( '/' TOKEN )+
• States and Territories– Owner
• federal– Suggested
• http://BASE/id/us/state/NAME– Example
• http://logd.tw.rpi.edu/id/us/state/Vermont
http://logd.tw.rpi.edu/instance-hub-uri-design
Linked Data & Semantic Web Technology
XML (Extensible Markup Language)• a textual data format for the representation of
arbitrary data structures over the Internet• both human-readable and machine-readable
<title> W3C Demonstrates …</title><date> 12 February 2013</date><body> W3C invites media, analysts, and other attendees of Mobile World Congress …</body>
Content
title
date
body
bold1
bold2
Structure
titledate
body
bold1
bold2
Presentation
XML DTDXML Schema
XSLTXSL-foXPath
Concept
RelatedRecommendations
http://en.wikipedia.org/wiki/Xml
Linked Data & Semantic Web Technology
Data Representation of XML• Various ways to represent data using XML
– Myungjin Lee is Hye-jin’s husband.
• We need a method to represent data on abstract level.
<conjugalrelation><husband>Myungjin Lee</husband><wife>Hye-jin Han</wife>
</conjugalrelation>
<conjugalrelation husband=“Myungjin Lee”><wife>Hye-jin Han</wife>
</conjugalrelation>
<conjugalrelation husband=“Myungjin Lee” wife=“Hye-jin Han” />
Linked Data & Semantic Web Technology
RDF (Resource Description Frame-work)
• a general method for conceptual description or modeling of information that is implemented in web resources, using a variety of syntax formats
– Myungjin Lee is Hye-jin’s husband.
hasWife
http://en.wikipedia.org/wiki/Resource_Description_Framework
Linked Data & Semantic Web Technology
Data Representation of RDF
hasWife
http://semantics.kr/myungjinlee http://semantics.kr/hye-jinhanhttp://semantics.kr/rel/hasWife
SubjectURI reference
PredicateURI reference
ObjectURI reference or Literal
Triple
Linked Data & Semantic Web Technology
RDF Example
http://www.cars.com/car#A6
http://www.cars.com/car#Car
http://www.cars.com/car#Gasoline
http://www.cars.com/car#GDI
http://www.cars.com/car#Auto_8-Speedhttp://www.cars.com/car#Sedan
4
http://www.cars.com/car#AWD
115”
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.cars.com/car#transmission
http://www.cars.com/car#wheelbase
http://www.cars.com/car#engine
http://www.cars.com/car#fuel
http://www.cars.com/car#drivetrain
http://www.cars.com/car#doors
http://www.cars.com/car#body_style
Linked Data & Semantic Web Technology
RDF Serialization• N-Triples
– RDF Test Cases, W3C Recommendation, 10 February 2004– a line-based, plain text serialization format for storing and transmitting RDF data
• Notation 3 (N3)– a shorthand non-XML serialization of RDF models, designed with human-readabil-
ity in mind– much more compact and readable than XML RDF notation
• Turtle (Terse RDF Triple Language)– W3C Candidate Recommendation, 19 February 2013– a format for expressing data in the Resource Description Framework (RDF) data
model– a subset of Notation3 (N3) language, and a superset of the minimal N-Triples for-
mat
• RDF/XML– W3C Recommendation, 10 February 2004– an XML syntax for writing down and exchanging RDF graphs
http://en.wikipedia.org/wiki/N-Tripleshttp://en.wikipedia.org/wiki/Notation3
http://en.wikipedia.org/wiki/Turtle_(syntax)
Linked Data & Semantic Web Technology
<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/title> "Tony Benn" .<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/publisher> "Wikipedia" .
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/"> <rdf:Description rdf:about="http://en.wikipedia.org/wiki/Tony_Benn"> <dc:title>Tony Benn</dc:title> <dc:publisher>Wikipedia</dc:publisher> </rdf:Description></rdf:RDF>
@prefix dc: <http://purl.org/dc/elements/1.1/>.
<http://en.wikipedia.org/wiki/Tony_Benn> dc:title "Tony Benn"; dc:publisher "Wikipedia".
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .@prefix dc: <http://purl.org/dc/elements/1.1/> .@prefix ex: <http://example.org/stuff/1.0/> .
<http://www.w3.org/TR/rdf-syntax-grammar> dc:title "RDF/XML Syntax Specification (Revised)" ; ex:editor [ ex:fullname "Dave Beckett"; ex:homePage <http://purl.org/net/dajobe/> ] .
N-Triple
RDF/XML
N3
Turtle
Linked Data & Semantic Web Technology http://www.w3.org/TR/rdf11-concepts/
Linked Data & Semantic Web Technology
RDF 1.0 vs RDF 1.1
RDF 1.0 RDF 1.1
Resource Identification URI IRI (Internationalized Re-source Identifier)
Multiple RDF Graphs X O
HTML content for literal value X rdf:HTML
Linked Data & Semantic Web Technology
Recommendations of RDF
http://www.w3.org/standards/techs/rdf#w3c_all
Linked Data & Semantic Web Technology
RDF Schema• W3C Recommendation, 10 February 2004• to define classes and properties that may be
used to describe classes, properties and other resources
• RDF Schema allows– Definition of Classes– Definition of Properties and Restrictions– Definition of Hierarchies
http://www.slideshare.net/lysander07/openhpi-22
Linked Data & Semantic Web Technology
RDF Schema Example
car:Car
car:Vehicle
rdfs:subClassOf
rdf:Property
car:body_stylerdfs:domain
rdfs:range
rdfs:Class
rdf:type
rdf:type
car:Style
rdf:type
car:A6
rdf:type
car:Sedanrdf:typecar:body_style
ABox - assertion component
TBox - terminological component
Linked Data & Semantic Web Technology
RDF Semantics• to provide a formal meaning based on a model-
theoretic semantics in its abstract syntax
<x, y> is in IEXT(I(rdfs:subClassOf))
if and only if x and y are in IC
and ICEXT(x) is a subset of ICEXT(y)
car:Car
car:Vehicle
rdfs:subClassOf
car:A6
rdf:type
rdf:type
Linked Data & Semantic Web Technology
SPARQL• Why do we need a query language for RDF?
– Why de we need a query language for RDB?– to get to the knowledge from RDF
• SPARQL Protocol and RDF Query Language– to retrieve and manipulate data stored in Resource
Description Framework format– to use SPARQL via HTTP
http://www.slideshare.net/lysander07/openhpi-semweb03part1
Linked Data & Semantic Web Technology
SPARQL ExamplePREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?name ?emailWHERE { ?person a foaf:Person. ?person foaf:name ?name. ?person foaf:mbox ?email.}
RDF Knowledge Base
?name ?email
Myungjin Lee [email protected]
Gildong Hong [email protected]
Grace Byun [email protected]
Linked Data & Semantic Web Technology
SPARQL Query Forms• SELECT query
– Used to extract raw values from a SPARQL endpoint, the results are returned in a table format.
• CONSTRUCT query– Used to extract information from the SPARQL endpoint
and transform the results into valid RDF.• ASK query
– Used to provide a simple True/False result for a query on a SPARQL endpoint.
• DESCRIBE query– Used to extract an RDF graph from the SPARQL endpoint,
the contents of which is left to the endpoint to decide based on what the maintainer deems as useful information.
http://en.wikipedia.org/wiki/SPARQL
Linked Data & Semantic Web Technology
OWL (Web Ontology Language)• knowledge representation languages for author-
ing ontologies• If you need more expressiveness OWL
– such as,
Man Woman∩ = Ø
Person Persondescendant
Persondescendant
descendant
Husband Wife1:1 _01 Action
hasGenre
ActionMovie
subClassOf
Genre
type
Linked Data & Semantic Web Technology
Linked Data Service
What more do we need?
Triple StoreRDBMS HTMLHTML
HTML
SPARQL
R2RML
Linked Data Platform
RDFa
GRDDL
RDFKnowledge+
Linked Data & Semantic Web Technology
R2RML• RDB to RDF Mapping Language• W3C Recommendation 27 September 2012• a language for expressing customized mappings
from relational databases to RDF datasets
<http://data.example.com/employee/7369> rdf:type ex:Employee.<http://data.example.com/employee/7369> ex:name "SMITH".
@prefix rr: <http://www.w3.org/ns/r2rml#>.@prefix ex: <http://example.com/ns#>.
<#TriplesMap1> rr:logicalTable [ rr:tableName "EMP" ]; rr:subjectMap [ rr:template "http://data.example.com/employee/{EMPNO}"; rr:class ex:Employee; ]; rr:predicateObjectMap [ rr:predicate ex:name; rr:objectMap [ rr:column "ENAME" ]; ].
R2RML
Result
RDB
http://www.w3.org/TR/r2rml/
Linked Data & Semantic Web Technology
Linked Data Platform• A set of best practices and simple approach for
a read-write Linked Data architecture, based on HTTP access to web resources that describe their state using RDF
• W3C Working Draft 25 October 2012
http://www.w3.org/TR/ldp/
Linked Data & Semantic Web Technology
RDFa (the Resource Description Framework in attributes)
• W3C Recommendation, 07 June 2012• to express machine-readable data in Web doc-
uments like HTML, SVG, and XML
Example<p vocab="http://schema.org/" resource="#manu" typeof="Person"> My name is <span property="name">Manu Sporny</span> and you can give me a ring via <span property="telephone">1-800-555-0199</span>. <img property="image" src="http://manu.sporny.org/images/manu.png" /></p>
http://www.w3.org/TR/xhtml-rdfa-primer/
Linked Data & Semantic Web Technology
GRDDL (Gleaning Resource Descriptions from Dialects of Languages)
• a mechanism and markup format for Gleaning Resource Descriptions from Dialects of Lan-guages to obtain RDF triples out of XML docu-ments, including XHTML
<html xmlns:grddl='http://www.w3.org/2003/g/data-view#' grddl:transformation="glean_title.xsl getAuthor.xsl"><head><title>Are You Experienced?</title></head>...
<xsl:stylesheet version="1.0"> <xsl:template match="/"> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="{$subject}"> <dc:title> <xsl:value-of select="/html:html/html:head/html:title"/> </dc:title> </rdf:Description> </rdf:RDF> </xsl:template></xsl:stylesheet>
<rdf:RDF> <rdf:Description rdf:about=""> <dc:title>Are You Experienced?</dc:title> </rdf:Description></rdf:RDF>
HTML
glean_title.xsl
RDF
http://www.w3.org/TR/grddl/
Linked Data & Semantic Web Technology
Jena Platform
Linked Data Service
Triple StoreRDBMS HTMLHTML
HTML
SPARQL
TDB & SDB
Jena API
Fuseki
ARQ & LARQ
http://jena.apache.org/
Linked Data & Semantic Web Technology
Openlink Virtuoso• a middleware and database engine hybrid that
combines the functionality of a traditional RDBMS, ORDBMS, RDF, XML, etc.– Relational Data Management– RDF Data Management– XML Data Management– Free Text Content Management & Full Text Index-
ing– Document Web Server– Linked Data Server– Web Application Server– Web Services Deployment (SOAP or REST)
http://virtuoso.openlinksw.com/
Linked Data & Semantic Web Technology
Openlink Virtuoso Coverage
Linked Data Service
Triple StoreRDBMS HTMLHTML
HTML
SPARQL
Sponger
SPARQL Server
Storage and Inference
Linked Data & Semantic Web Technology
The Linking Open Data cloud diagram
Linked Data & Semantic Web Technology
http://lod-cloud.net/
Linked Data & Semantic Web Technology
MediaUser Generated Content
Publications
Government
Geographic
Cross-DomainLife Sciences
Linked Data & Semantic Web Technology
Domain Number of datasets Triples (Out-)Links
Media 25 18,4185,2061 5044,0705
Geographic 31 61,4553,2484 3581,2328
Government 49 133,1500,9400 1934,3519
Publications 87 29,5072,0693 1,3992,5218
Cross-domain 41 41,8463,5715 6318,3065
Life Sciences 41 30,3633,6004 1,9184,4090
User-generated Content 20 1,3412,7413 344,9143
Total 295 316,3421,3770 5,0399,8829
http://www.slideshare.net/lysander07/13-semantic-web-technologies-linked-data-semantic-search
Linked Data & Semantic Web TechnologyLinked Data & Semantic Web Technology
KDATA (Linked Data for Korea)Domain Triples국가코드 3,899
엔터테인먼트 44,278 행정구역 2,969
초중고등학교 126,469 교육청 1,130 대학교 2,833
사회적 기업 5,539 서울시 개방 화장실 47,340
야구선수 및 팀 228,872 지하철역 4,450
역사 5,392 행정데이터표준용어 109,101
한옥마을 1,155 공공 WiFi 설치정보 1,671 KDATA 분류용어 808
전통시장 4,535 국립공원 10,605
문화재 80,156 공공체육시설 49,799
생물분류 3,256 문화시설 9,418
공원정보 및 프로그램 2,429 가격안정모범업소 16,212
가격안정모범업소 상품목록 14,300 공공시설물 인증제품 6,931
제설함 위치정보 39,218 야생동식물정보 115,099
야생동식물 출현정보 139,608 합계 1,077,472
http://kdata.kr/index.jsp
Linked Data & Semantic Web Technology
<rdf:RDF><rdf:Description rdf:about="http://data.kdata.kr/data/Namdaemun?output=rdfxml"> <rdfs:label>RDF description of Namdaemun</rdfs:label> <foaf:primaryTopic> <kdc:StateDesignatedHeritage rdf:about="http://data.kdata.kr/resource/Namdaemun"> <rdfs:label>남대문 </rdfs:label> <rdfs:label>숭례문 </rdfs:label> <foaf:depiction rdf:resource="20060227132556895000.jpg"/> <owl:sameAs rdf:resource="http://dbpedia.org/resource/Namdaemun"/>...</rdf:RDF>
http://data.kdata.kr/resource/Namdaemun
HTML
RDF
select ?swhere { ?s rdf:type <http://data.kdata.kr/class/NationalTreasure> . ?s rdfs:label "남대문 " .}
SPARQL
Contents Search on the Semantic W
eb Dr. Myungjin Lee
e-Mail : [email protected] : http://twitter.com/MyungjinLee
Facebook : http://www.facebook.com/mjinlee
SlideShare : http://www.slideshare.net/onlyjiny/
Thanks foryour attention.