Linked Data Technology & Status

warbarnacleΑσφάλεια

5 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

92 εμφανίσεις


Linked Data & Semantic Web Technology

Linked Data

Technology & Status

Dr.
Myungjin

Lee


Linked Data & Semantic Web Technology

The Semantic Web

an elemental
syntax

for
content
structure

within
documents

a simple
language

for
expressing data
models,

which
refer to objects ("resources
")

and
their relationships

more
vocabulary

for
describing properties and classes

a vocabulary for
describing

properties
and
classes

of
RDF
-
based resources

a protocol and query
language

for
semantic web data sources

to exchange
rules

between
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
information 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

★★

A癡楬慢汥 慳 浡捨楮m
-
r敡摡扬攠獴牵捴畲敤e摡瑡 ⡥⹧⸠
數捥氠楮獴敡i 潦 業慧攠獣慮 潦 愠瑡扬攩

★★★

慳 ⠲⤠灬畳p湯n
-
灲潰物整慲礠景牭慴 ⡥⹧⸠䍓V 楮獴敡i
潦 數捥氩e


★★★★

䅬氠瑨攠慢潶攠灬畳Ⱐ啳攠
潰敮e獴s湤nr摳d晲潭o圳W
⡒䑆 慮搠卐䅒兌⤠瑯 楤敮瑩晹i瑨楮杳
Ⱐ獯 瑨慴 灥潰汥
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
syntax

for
content
structure

within
documents

a simple
language

for
expressing data
models,

which
refer to objects ("resources
")

and
their relationships

a vocabulary for
describing

properties
and
classes

of
RDF
-
based resources

a protocol and query
language

for
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
"> &
nbsp;at

<a
href
="http://kdata.kr">kdata.kr
</a>

identifies

and

names

represents

looks up

URI

http://
dbpedia.org/resource/Namdaemun

URI

http://data.kdata.kr/resource/Sungnyemun





links

refers

Person

Machine



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:alice@example.com>
;


foaf:homepage

<http://www.example.com/people/alice>

.

ID

RDF

HTML

Resource identifier (URI)

RDF document URI

HTML document URI

for web browsers

for semantic web applications

http://www.w3.org/TR/cooluris/


Linked Data & Semantic Web Technology

Distinguishing between Representations and Descriptions

Generic

Document

RDF

HTML

http://data.kdata.kr/page/Namdaemun

http://
data.kdata.kr/page/Namdaemun.rdf

http://
data.kdata.kr/page/Namdaemun.html

text/html

application/
rdf+xml

Thing

http://data.kdata.kr/resource/Namdaemun

303 redirect

content

negotiation


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
concept


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
-
sector

http://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

title

date

body

bold1

bold2

Presentation

XML

DTD

XML Schema

XSLT

XSL
-
fo

XPath

Concept

Related

Recommendations

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 Framework)


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
-
jinhan

http://
semantics.kr/rel/hasWife

Subject

URI reference

Predicate

URI reference

Object

URI 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
-
Speed

http://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
-
readability 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 format



RDF/XML


W3C
Recommendation,
10 February 2004


an XML syntax for writing down and exchanging RDF graphs

http://
en.wikipedia.org/wiki/N
-
Triples

http://
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
Resource 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_style

rdfs:domain

rdfs:range

rdfs:Class

rdf:type

rdf:type

car:Style

rdf:type

car:A6

rdf:type

car:Sedan

rdf:type

car: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 Example

PREFIX
foaf
: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?
email

WHERE {



?
person a
foaf:Person
.



?
person
foaf:name

?name
.



?
person
foaf:mbox

?email
.

}

RDF Knowledge Base

?name

?email

Myungjin

Lee

mjlee@li
-
st.com

Gildong

Hong

gildong@daum.net

Grace
Byun

grace@naver.com


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
authoring
ontologies


If you
need
more
expressiveness


佗O


such as,

Man

Woman



=
Ø

Person

Person

descendant

Person

descendant

descendant

Husband

Wife

1:1

_01

Action

hasGenre

ActionMovie

subClassOf

Genre

type


Linked Data & Semantic Web Technology

Linked Data Service

What more do
we
need?

Triple Store

RDBMS

HTML

HTML

HTML

















SPARQL

R2RML

Linked Data Platform

RDFa

GRDDL

RDF

Knowledge

+


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
documents 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
Languages
to obtain RDF triples
out of XML
documents, 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 Store

RDBMS

HTML

HTML

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
Indexing


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 Store

RDBMS

HTML

HTML

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

Media

User Generated Content

Publications

Government

Geographic

Cross
-
Domain

Life 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 Technology


Linked Data & Semantic Web Technology

KDATA (Linked Data for Korea)

Domain

Triples

국가코드



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






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



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 ?
s

where {


?s
rdf:type

<http://data.kdata.kr/class/NationalTreasure>
.


?s
rdfs:label

"
남대문
"
.

}

SPARQL

Contents Search on the Semantic Web

Dr.
Myungjin

Lee



e
-
Mail : mjlee@li
-
st.com

Twitter : http://twitter.com/MyungjinLee

Facebook

: http://www.facebook.com/mjinlee

SlideShare

: http://www.slideshare.net/onlyjiny/