Semantic Web and Knowledge Management

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20 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Semantic Web and

Knowledge Management

Ching
-
Long Yeh
葉慶隆

Department of Computer Science and Engineering

Tatung University

Taipei, Taiwan

Email: chingyeh@cse.ttu.edu.tw

http://www.cse.ttu.edu.tw/chingyeh

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Content


Web technology evolution


Semantic Web


Ontology and Languages


Semantic Web Service


Semantic Web Applications


Summary

Web Technology Evolution

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Web Technology


HTML, HTTP


XML


Electronic Business


Semantic Web

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Information

Pool

WWW

HTTP (Hyper Text Transport Protocol)

HTML (Hyper Text Markup Language)

URL (Uniform Resource Locator)

Web server

Application

Client

HTTP

URL

HTML Document


Human
-
to
-
machine interaction


Information explosion

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Information

Pool

Interaction Using XML

XML (eXtensible Markup Language)

SOAP (Simple Object Access Protocol)

SOAP server

Application

HTTP

XML Document


Machine
-
to
-
machine interaction


Service automation

SOAP server

Application

Information

Pool

XML Document

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Web Service Architecture

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Electronic Business

Transport, routing,

packaging

Business processes,

business documents

Company A

Company B

Transport, routing,

packaging

Business processes,

business documents

ERP

ERP


Application
-
to
-
Application


Business Process Automation


RosettaNet


ebXML

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Semantic Web


The Semantic Web is a vision:


See “
W3C Semantic Web Activity
,” by Marja
-
Riitta Koivunen, for more
descriptions.

the idea of having data on the web defined and linked in
a way that it can be used by machines not just for
display purposes, but for automation, integration and
reuse of data across various applications

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Semantic Web


The Semantic Web is the new generation of the World Wide
Web, based on the
semantic network knowledge representation

formalism, which enables packaging information in the form of
object
-
attribute
-
value

statements, so called
triplets
.


By assuming that terms used in these statements are based on
the formally specified meaning (for the community of interest),
i.e. ontologies, these triplets can be semantically processed by
machine agents.

From: http://www2002.org/CDROM/poster/130.pdf

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The Semantic Web Layered Architecture

(
http://www.w3.org/2001/T
alks/0228
-
tbl/slide5
-
0.html)

Tim Berners
-
Lee:

“Axioms, Architecture and
Aspirations”

W3C all
-
working group
plenary Meeting

28 February 2001

URI

Unicode

XML

Namespaces

XML Schema

Sig

RDF M&S

RDF Schema

Ontology

Rules

Logic

Proof

Trust

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The Big Picture
of SW

(http://semanticweb.org/about.html#bigpicture)

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The metadata layer of the
Semantic Web

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What Is in an Ontology?



One widely cited definition of an ontology is Gruber’s [Gruber
1993]
“A specification of a conceptualization”
.


An
ontology

is a formal explicit description of


concepts in a domain of discourse (
classes
(sometimes called
concepts
)),


properties of each concept describing various features and
attributes of the concept (
slots
(sometimes called

roles
or

properties
)), and


restrictions on slots (
facets
(sometimes called
role restrictions
)).


An ontology together with a set of individual instances of classes
constitutes a
knowledge base
.

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Ontology Spectrum

(From: http://www.ksl.stanford.edu/people/dlm/papers/ontologies
-
come
-
of
-
age
-
mit
-
press
-
(with
-
citation).htm)

Semantic Web Languages

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What is XML?


Extensible Markup Language


A Syntax for Documents


A Meta
-
Markup Language


A Structural and Semantic Language, not a Formatting
Language


Not just for Web pages

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XML Standards


DTD


Namespace


Schema


DOM


CSS, XSL
-
T, XSL
-
FO


XLink


XPointer

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XML Protocol: SOAP

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RDF M&S


RDF (Resource Description Framework)


Beyond Machine readable to
Machine understandable


RDF consists of two parts


RDF
M
odel (a set of triples)


RDF
S
yntax (different XML serialization syntaxes)


RDF Schema for definition of Vocabularies (simple
Ontologies) for RDF (and in RDF)

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RDF Data Model


Resources


A resource is a thing you talk about (can reference)


Resources have URI’s


RDF definitions are themselves Resources (linkage, see
requirement 1)


Properties


slots, define relationships to other resources or atomic values


Statements



Resource

has
Property

with
Value



(Values can be resources or atomic XML data)


Similar to Frame Systems

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A Simple Example


Statement


“Ora Lassila is the creator of the resource
http://www.w3.org/Home/Lassila



Structure


Resource

(subject)


http://www.w3.org/Home/Lassila


Property

(predicate) http://www.schema.org/#Creator


Value

(object) "Ora Lassila



Directed graph

http://www.w3.org/Home/Lassila

s:Creator

Ora Lassila

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OWL

W3C Web Ontology Language


OWL provides three increasingly expressive
sublanguages:
OWL Lite
,
OWL DL
, and
OWL Full
.

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OWL

W3C Web Ontology Language

OWL Lite language constructs

RDF Schema Features:


Class


rdf:Property


rdfs:subClassOf


rdfs:subPropertyOf


rdfs:domain


rdfs:range


Individual

(In)Equality:


equivalentClass


equivalentProperty


sameAs


differentFrom


allDifferent


Property Characteristics:


inverseOf


TransitiveProperty


SymmetricProperty


FunctionalProperty


InverseFunctionalProperty

Property Type Restrictions:


allValuesFrom


someValuesFrom

Restricted Cardinality:


minCardinality

(only 0 or 1)

maxCardinality

(only 0 or 1)

cardinality

(only 0 or 1)

Header Information:


ontology


imports

Semantic Web Services

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Some Motivating Tasks


The kinds of task we expect OWL
-
S to enable:


Automatic Web service
discovery



Automatic Web service
invocation



Automatic Web service
composition

and
interoperation



Automatic Web service
execution monitoring


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High
-
level View of the Service Ontology

ServiceProfile

ServiceModel

ServiceGrounding

Service

Resource

provides

presents

describedBy

supports

What the

service does

How it works

How to

Access it

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Top Level of the Process Ontology

Process

Profile

Atomic

Process

Composite

Process

Simple

Process

Control

Construct

Sequence

Repeat

Until

ProcessComponent=

Process U ControConstruct

ProcessComponent=

Process U ControConstruct

ProcessComponent=

Process U ControConstruct

hasProcess

hasProfile

computedInput

computedOutput

computedEffect

computedPrecondition

invocab

compsedBy

expand

collapse

realizes

realizedBy

has

Grounding

Input

Precondition

Output

effect

Condition

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Grounding a Service to a Concrete Realization

Process Model

Atomic Process

Operation

DL
-
Based Types

Inputs/Outputs

Message

Binding to SOAP, HTTP, etc.

WSDL

OWL
-
S

Semantic Web Services Architecture

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Introduction


Develop architectural and protocol abstractions
forming a reference architecture to support Semantic
Web Service technologies


The support functions the architecture will cover


Dynamic Service Discovery


Service Process Enactment and Management


Negotiation and Contracting


Semantic Web Community Support Services


Semantic Web Service Lifecycle and Resource Management
Services


Cross
-
cutting Issues

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Introduction


Semantic Web Services are viewed as a way to
extend the capabilities of web services in the
direction of dynamic interoperability.


Commercial web services, in both B2B and B2C applications


Grid computing


Ubiquitous computing


Information Services

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Functional Areas

Dynamic Service Discovery

B2B


B2C


Ubiq


Grid


Info


Advertising of Service Descriptions





















Candidate Service Query Formulation





















Candidate Service Matchmaking





















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Functional Areas

Service Process Enactment and Management

B2B


B2C


Ubiq


Grid


Info


Candidate Service Selection





















Service request formation and response interpretation





















Request and Response Translation





















Choreography interpretation and execution





















Process mediation and delegation





















Dynamic Service Composition





















Process status monitoring and event notification





















Service failure handling and compensation





















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Functional Areas

Negotiation and Contracting

B2B


B2C


Ubiq


Grid


Info


Service contract negotiation





















Dispute Resolution and Compliance





















Non
-
Repudiation/Audit
Tracking/Explanation





















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Functional Areas

Semantic Web Community Support Services


B2B


B2C


Ubiq


Grid


Info


Ontology Management and Mapping Services





















Service catalog and Information brokering Services





















Membership and Authority Services





















Security (identification/authentication, authorization, delegation)





















Privacy Services





















Reputation Services





















Policy and Protocol Management Services





















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Functional Areas

Service Lifecycle Support

B2B


B2C


Ubiq


Grid


Info


Executable process management services





















Resource Allocation and Provisioning services





















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Summary


Abstractions of services on emerging technological
architectures


The Semantic Web Service Architecture is probably
an integration of the abstractions of services for
various functional areas.


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An Architecture of
Semantic Community Web Portals

(From: http://www9.org/w9cdrom/134/134.html)

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Development of Web Portals

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A KM Framework over SW

(From: http://www2002.org/CDROM/poster/130.pdf)

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What is Sesame ?

Sesame is RDF Schema
-
based repository

and querying facility that offers:



A persistent store of RDF data


Export of repository contents in RDF format


Data administration functionality


Query engine (RQL , SeRQL)

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Sesame’s Architecture

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An Ontology
-
Based

Portal for Digital Library


Services

Syntax Transformation of RDF

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What is RDF


RDF (
R
esource
D
escription
F
ramework)


The common language used for the semantic interoperability of the Semantic
Web.


Consisting of


a data model in directed labeled graph and


the corresponding XML serializations

<
rdf
:RDF>


<
rdf
:Description about="http://www.w3.org/Home/Lassila">


<
s
:Creator>


<
rdf
:Description about="http://www.w3.org/staffId/85740">


<
v
:Name>Ora Lassila</
v
:Name>



<
v
:Email>lassila@w3.org</
v
:Email>


</
rdf
:Description>


</
s
:Creator>


</
rdf
:Description>

</
rdf
:RDF>

http://www.w3.org/Home/Lassila

Ora Lassila

lassila@w3.org

Creator

Name

Email

<
rdf
:RDF>


<
rdf
:Description about="http://www.w3.org/Home/Lassila">


<
s
:Creator
rdf
:resource="http://www.w3.org/staffId/85740"/>


</
rdf
:Description>


<
rdf
:Description about="http://www.w3.org/staffId/85740">


<
v
:Name>Ora Lassila</
v
:Name>


<
v
:Email>lassila@w3.org</
v
:Email>


</
rdf
:Description>

</
rdf
:RDF>

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(RDF in XML)
n

(RDF in XML)
i

(RDF in XML)
2

(RDF in XML)
1

DOM +

Procedure
1

A single RDF

data model

Multiple

RDF in XML

DOM +

Procedure
2

DOM +

Procedure
i

DOM +

Procedure
n

Transformation of

RDF Using DOM

Transformation of RDF Using DOM

Result
i

Transformation

results

Problem

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A single RDF

data model

Multiple

RDF in XML

Transformation of

RDF Using DOM

Result
i

Transformation

results

Syntax
-
directed Transformation of RDF

(RDF in XML)
n

(RDF in XML)
i

(RDF in XML)
2

(RDF in XML)
1

Syntax
-
directed

Transformation

Goal

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Two System Architectures

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RDF Grammar to Yacc Rules

An RDF Grammar Rule

RDF ::= ['<rdf:RDF>'] obj* ['</rdf:RDF>']

Revision

RDF ::= xmlDeclaration stgRDF obj* etgRDF

xmlDeclaration::= ‘<?xml’ ‘version’ ‘=‘ ‘1.0’ encoding ‘>’

encoding::= ‘encoding’ ‘=‘ coding | empty

stgRDF::= '<‘ ‘rdf:’ ‘RDF’ namespaceDef xmlBase ‘>‘ | empty

etgRDF::= '<‘ ‘/’ ‘rdf:’ ‘RDF’ ‘>‘ | empty

def p_stgRDF(t):


'stgRDF : LP rdf RDF


namespaceRule xmlbaseRule RP'

def p_etgRDF(t):


'etgRDF : LP DIV rdf RDF RP'

def p_namespaceRule(t):


'''namespaceRule : namespace


| empty'''

def p_xmlbaseRule(t):


'''xmlbaseRule : xmlbase1


| empty'''

def p_empty(t):


'empty : '


pass

Yacc Rules

def p_RDF(t):


'RDF_file : xmlDeclaration RDFRule‘


global triplec; triplec=len(triple)


storeNamaspace(); storeResource();


storeProperty(); storeObject();


storeTriple(); displayTripleTable()


def p_xmlDeclaration(t):


'''xmlDeclaration : declaration


| empty'''

def p_RDFRule(t):


'''RDFRule : stgRDF obj etgRDF


| obj'''

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RDF Grammar to DCG Rules

An RDF rule

description::='<rdf:Description' idAboutAttr? bagIdAttr? propAttr* '/>' |


'<rdf:Description' idAboutAttr? bagIdAttr? propAttr* '>‘


propertyElt* '</rdf:Description>' |


typedNode

The DCG rule:

description(_)
--
>


halfSTG('Description',NS),(idAboutAttr(IdAboutAttr);[]),


(bagIdAttr(BagIdAttr);[]),propAttrStar(IdAboutAttr),


(['/>']
;['>'],


propertyEltStar(_,IdAboutAttr),fullETG('Description',NS)),


{reificationOfStatements(IdAboutAttr,BagIdAttr),!}


;typedNode.

DCG rules for converting RDF to Triples and frames


% RDF to Triple

obj(Obj)
--
>


container(Obj);description(_),{getAllTriples(Obj)}.

%RDF to KSL

obj(Obj)
--
>


container(Obj);description(_),{getKSLDocument(Obj)}.

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Conclusion


The Web is evolving toward automation of resource
consumption and services


Electronic Business


Semantic Web and Services


The Semantic Web Service Architecture is probably
an integration of the abstractions of services for
various functional areas.


Commercial applications, including B2B, and B2C


Grid computing


Ubiquitous computing


Information services