tu/e eindhoven university of technology pacis'03 july 2003 1 engineering semantic web...

PACIS'03

TU/e eindhoven university of technology

July 2003 1

Engineering Semantic Web Information Systems

Richard Vdovjak

Flavius Frasincar

Geert-Jan Houben

Peter Barna

Databases & Hypermedia Group

Department of Computer Science

/dept. of mathematics and computer science wwwis.win.tue.nl/~hera

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Overview

• Motivating example: Virtual art gallery• Hera framework, models and

technologies• Hera Back-end: Integration engine• Hera front-end: Presentation generation

engine• Summary and future work

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• Create “on-the-fly” exhibitions– painters, paintings, techniques...

• Many to many content delivery • Triggered by the user query • Exhibits (Images) are from (online) Art catalogues• Descriptions are gathered from an (online) Art

Encyclopedia

Virtual art gallery WIS

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We need a framework that offers

• Semantics– Express concepts and their hierarchies

– Relationships among the concepts

– Query language that can exploit the above

• Access to several sources– Flexible source management

– Flexible query mediation

• User/platform adaptation

– (adaptability and adaptivity)

• Automated presentation design– Based on the user query,

– Device profiles and the browsing history

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July 2003 5

The Hera Framework: Design Steps, Models, and Processing Engines

Hera Suite

Design Methodology

RequirementsAnalysis

ConceptualDesign

IntegrationDesign

ApplicationDesign

AdaptationDesign

PresentationDesign

(Search)Agent

inforequest

(meta) data

ConceptualModel Application

Model

info request(slice)

presentation

End User

RQL / RDF XSLT / XML

UserModel

PresentationModel

PresentationEngine

ApplicationEngine

IntegrationEngine

CuypersEngine

AdaptationEngine

info request HTML/WML

IntegrationModel

Semantic Layer Application Layer Presentation Layer

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Overview of the System

Integration Engine Presentation Engine

Conceptual Model

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Conceptual Model (CM)

• Provides a uniform semantic view over different data sources that are integrated within a given Web application

• Consists of hierarchies of concepts relevant within the given domain, their properties, and relations

• Encoded in RDF(S)

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RDF(S), RQL

• RDF(S)– W3C standard for describing metadata

– Directed labeled graph formalism

– Formal semantics defined

• RQL:select X from {X:Technique}tname{Xtname} where Xtname = "Chiaroscuro"

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Conceptual Model Example

ArtifactTechnique Creator

Painting

Image

Integer

String

Conceptual Model (cm)String

Painter

String

String

String

xy property "xy"subPropertyOfsubClassOf

exemplified_by

exemplifies

created_by

creates

painted_by

paints

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July 2003 10

Art EncyclopediaArt Encyclopedia (ae)

ArtTechniqueLiteral

Literal

title

Artist

Literal

used

Tec

hniq

ue

biography

ArtPiece

Literal title

Literal date

Literal


Art Catalogue (ac)

Exhibit

VisualArt

Music Piece

AudioArt

Painting

LiteralLiteral

MoviePhoto

Literalexhibited

Literalvisualized

creationDatetitle

Literal

Source Clusters

Sources are

• Autonomous

• (Virtually) grouped to clusters based on the content they provide

• RDF(S), RQL capable

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Integration Model

IM decouples the CM and Sources • Articulations

– actual links between the CM and the source ontologies– concept/instance uniqueness – (a part of it) serves as a query on the source side

• Decorations– offer a way to rank sources within the same cluster– capture explicitly designer’s knowledge about sources– the order in which the sources are consulted is flexible– open possibilities for queries with constraints

e.g. “I’m interested in the answer within 1 s, otherwise forget it”

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Integration Model Ontology

Integration ModelSpecialization

IntegrationModel Ontology

Reliability

ResponseTime

Decoration

Articulation To

FromLiteral

Comparator

PathExpressionNode

rdfs:Resource

Edge

rdf:Property

begins

ends

starts ToNode

starts FromNode

PrimaryNode

ProcInstruction

Transformer

Literal2String

Sn2UriTrans


backtrack

follow

target

applies

obtainedFrom

srcAddress

Literal

App

lica

tion

inde

pend

ent

• Path expression– Primary node (including its

ID)– Sequence of nodes and edges

• Articulation– Target and Source path

expressions

• Decoration– Value based ordering criterion – e.g. ResponseTime, Reliability

• Processing instruction– Transformers (e.g.

Literal2String)

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Integration Model Instance:Articulation Example

a2_1

pe_to3

pe_from3

cm:Painting

ac:Painting

cm:picture

ac:visualized

d2_1 0.9

URL2ImageTransfac:title

target

source

starts

starts

idByValue

obtainedFrom

idByValuetransformedBy

obtainedFrom

follow ends

follow

http://www…ac

appliessrcAddress

Decoration (Reliability)

Source Path Expression(query for the source)

Target Path Expression

cm:aname

endsLURL

Image

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Source Management

Integration ModelSpecialization

IntegrationModel Ontology

Reliability

ResponseTime

Decoration

Articulation To

FromLiteral

Comparator

PathExpressionNode

rdfs:Resource

Edge

rdf:Property

begins

ends

starts ToNode

starts FromNode

PrimaryNode

ProcInstruction

Transformer

Literal2String

Sn2UriTrans


backtrack

follow

target

applies

obtainedFrom

srcAddress

Literal

Back-end Front-end

Sources

User Query

Presentation

Integration Model

IM Specialization

Conceptual Model

IM Instance

Access Point

html/smil

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Query answering

• Query mediation – For every variable in the query find articulations in the

IM instance pool – If there more articulations for one variable sort them

based on the chosen decoration(s) – Execute the “source” path expression queries at the the

sources – Perform the required processing instruction/data

transformations– Assemble the results

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Application Model (AM)

• AM serves as a presentation blue-print• Describes hypermedia aspects of the presentation.• Captures the navigational view over the CM• Consists of (nested) slices and slice relationships

– Slices - meaningful presentation units• Associated to concepts from the CM• Contain properties and possibly other slices (nesting)

– Slice relationships:• Aggregation relationships: index, tour, indexed guided tour…• Reference relationships: link with an anchor specified.

• Encoded in RDF(S).

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Application Model Example

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Adaptation/User Model

• Captures two kinds of adaptation– Adaptability takes into account the situation in which the user will use

the presentation (e.g. the browsing platform). – Adaptivity means that the presentation changes itself according to the

“state of the user’s mind” while being browsed.

• Consists of – Device/User Profile captures “static” visual and platform preferences

encoded in CC/PP.– User Session represents the dynamic user’s state, e.g. did the user visit

(learn) this slice (concept). – Application and Update Rules describe the behavior of the presentation

(e.g. conditional slices in AM) and keep the User Session up-to-date (AHAM rules).

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Adaptation Model Example

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Adaptation Model Syntax

• Adaptability Condition

• Adaptivity Condition

<rdfs:Class rdf:ID=“Slice.painter.main”

slice:condition=“um:Technique < 10”>

<rdf:subClassOf rdf:resource=“#Slice”/>

</rdfs:Class>

<rdfs:Class rdf:ID=“Slice.painting.picture”

slice:condition=“prf:ImageCapable=Yes”>

<rdf:subClassOf rdf:resource=“#Slice”/>

</rdfs:Class>

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Profile Example

• Device/User Profile (CC/PP encoding)Screen size: 100x80, preferred language: English

<ccpp:component>

<up:UserPreferences>

<up:Language>English</up:Language>

…

</up:UserPreferences>

</ccpp:component>

</rdf:Description>

<rdf:Description rdf:about=“Profile”>

<ccpp:component>

<prf:HardwarePlatform>

<prf:ImageCapable>No</prf:ImageCapable>

<prf:ScreenSize>100x80</prf:ScreenSize>

…

</prf:HardwarePlatform>

</ccpp:component>

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July 2003 22

XSL

Rendering• XSLT code generation• Different code generators:

– HTML for PC Web browsers

– SMIL code for multimedia presentations

– WML code for WAP phone browsers

XSL

<xsl:template match=“slice-instance”>

<TABLE>

<xsl:apply-templates select=“*”/>

</TABLE>

</xsl:template>

<xsl:template match=“slice-instance”>

<CARD id=“{@id}”>

<xsl:apply-templates select=“*”/>

</CARD>

</xsl:template>

HTMLWML

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Resulting Hypermedia Presentations

HTML

WML

SMIL

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EROS: exploring the CM

• Explorer for RDFS-based OntologieS

• multiple views over the same model

• support for RQL queries construction

,::

,::: 22212111

LRCVARpDCVAR

LRCVARpLRCVARpDCVAR

nnnnn

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July 2003 25

Summary

CM inRDF, RDFS

RQL

IM ArticulationsIM Decorations

AM inRDF, RDFS

UM, U/P Profile (CC/PP)

Hera:• Semantics– Express concepts and their hierarchies

– Relationships among the concepts

– Query language that can exploit the above

• Access to several sources– Flexible source management

– Flexible query mediation

• User/platform adaptation

– (adaptability and adaptivity)

• Automated presentation design– Based on the user query,

– Device profiles and the browsing history

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July 2003 26

Present & Future Work

• Applying our approach in different domains– Virtual museum

– Photo Portal

– Medical science (drug/disease ontologies)

• Optimization issues• Authoring tools for the underlying models

– Initial correlation for Schema Integration

tu/e eindhoven university of technology pacis'03 july 2003 1 engineering semantic web...

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